Slaughter conditions to optimise chevon meat quality

Determination of slaughter conditions to optimise chevon visual and eating quality

Industry Sector: Cattle and Small Stock

Research focus area: Animal Products, Quality and Value-adding

Research Institute: Agricultural Research Council – Animal Production Institute

Researcher: Dr L Frylinck PhD

Title Initials Surname Highest Qualification
Prof PE Strydom PhD
Prof EC Webb PhD Animal Science
Dr P Pophiwa PhD Animal Science
Prof LC Hoffman PhD Animal Science
Ms GL van Wyk MSce (Registered for PhD)
Ms JD Snyman ND Histologie

Year of completion : 2018

Aims of the project

  • To determine the expression of genomic markers in five South African purebred genotypes – Bos indicus
  • To determine the optimum slaughter procedures (electrical stimulation for 15 – 60 seconds or delayed/step wise chilling – time determined by optimal pH) for carcasses from castrated and intact male goats of two breed types: Boer Goats and Indigenous Veld Goats (IVG, Eastern Cape Xhosa or Northern Cape Speckled Goats
  • To evaluate the tenderness and connective tissue characteristics in six different muscles m. longissimus thoracis et longissimus (LTL), m. semimenbranosus (SM), biceps femoris (BF), supra spinatus (SS), infra spinatus (IS) and semitendanosus (ST) in electrical stimulated carcasses of Boer Goats and IVG from castrated and intact male goats.
  • To evaluate the tenderness and calpain system ageing related characteristics in m. longissimus thoracis et lumborum (LTL) and m. semimembranosus (SM) muscles of electrical stimulated and non-stimulated carcasses of Boer Goats and IVG from castrated and intact male goats.
  • To evaluate sensory attributes and other meat quality characteristics of chevon from the respective post-slaughter treatments in m. longissimus thoracis et lumborum (LTL) and m. semimembranosus (SM) muscles of electrical stimulated and non-stimulated carcasses of the two breed types; Boer Goats and IVG from castrated and intact male goats.

Executive Summary

The demand for goat meat in South Africa is relatively low because of traditional perceptions of off smells, off flavours and expected toughness. Perceptions also exist that Indigenous Veld Goat (IGV) produce tougher meat than Boer Goat (BG) specially bred to be a meat producing breed. The name indigenous goat is perceived as being small and not suitable for meat production. It is now discovered that some Indigenous Eco-types of Southern Africa, compare well with the Boer goat in size, can also produce good meat products if good farming and rearing practices are followed. Except for the advantage to preserve the indigenous breeds for the future generations, these breeds are well adapted to the harsh climate conditions in Southern Africa and are hardy with minimum need for veterinary intervention. Production and slaughter procedures should be adapted to suit the characteristics such as the low glycolytic potential and low carcass fat of goat carcasses. There is therefore a need to optimise the pre- and post-slaughter procedures in order to optimise the chevon (goat meat) visual and eating quality.

The first aim were investigated by applying different pre- and post slaughter procedures such as castration or not, applying electrical stimulation for 20 and 30 seconds or apply stepwise chilling. The monitoring of the muscle pH and temperature, muscle energy, meat colour and tenderness showed that either controlled step wise chilling or electrical stimulation of at least 30 sec will prevent cold toughening and produce ideal conditions for the intra muscular proteolytic enzymes to optimally function. It was found that castrated animals produced more tender meat than intact carcasses, but that more subcutaneous fat were produced, which could be advantageous to its eating experience. Both breed types: Boer Goats and Indigenous Veld Goats (IVG, Eastern Cape Xhosa or Northern Cape Speckled Goats, showed the same advantage in tenderness and colour if slaughter conditions were optimised.

The intrinsic characteristics of the six different muscles m. longissimus (LTL), m. semimenbranosus (SM), biceps femoris (BF), supra spinatus (SS), infra spinatus (IS) and semitendanosus (ST) differed from each other as expected, but castrated muscles had an higher intramuscular fat content – up to 4% than that on intact carcasses – similar in both breed-types tested. Percentage collagen solubility did not differ between the different muscles, but the total collagen measured in each muscle type did differ. Thus is optimal cooking method important.

Evaluating the tenderness and calpain system ageing related characteristics in m. longissimus thoracis et lumborum (LTL) and m. semimembranosus (SM) muscles of electrical stimulated and non-stimulated carcasses of Boer Goats and IVG from castrated and intact male goats confirm that the breed types did not differ in tenderness, but castration do have an advantageous effect on tenderness. It is said for beef that sarcomere length (SL) longer than 1.7 µm does not influence tenderness, but in this project it was obvious that the shorter 1.8 µm sarcomere length compared to that of our first subproject of 2 µm could have influenced meat tenderness. It is said that the calpain system works more effectively when the SL length is longer.

Sensory panel evaluation showed attributes and other meat quality characteristics of chevon from the respective post-slaughter treatments in m. longissimus (LTL) and m. semimembranosus (SM) muscles of electrical stimulated and non-stimulated carcasses of the two breed types; Boer Goats and IVG from castrated and intact male goats. Overall it seems like the sensory panel found the LTL and SM muscles tough, although the shear force measurements was not exactly inline with their findings. As mentioned before, the slaughter conditions could have been chosen better, for instance the ES should have been 30 sec and not 20 sec. Delayed/stepwise chilling could have given better results. I do recommend though that if a future sensory panel study is being done, mutton should be included to remove the possibility of biasness. Although I have no reason to doubt the professionalism of the panel, I do think that there could be a possibility of a negativity towards goat meat.

The evaluation of carcass characteristics and yield of electrical stimulated and non-stimulated carcasses of the two breed types; Boer Goats and IVG from castrated and intact male goats (additional aim) showed more differences between castrated and non-castrated carcasses than between carcasses of the two breed types. The dressing percentages did not differ between the castrated breeds, but was a bit higher that that of the intact carcasses. There was no significant differences in the percentage meat yield between breeds, although the different commercial cuts could differ a bit in sizes, mainly because of different ratios and form of different parts of the carcass that is genotypic-ally expected.

From this project a better understanding is formed on how goat temperament differ from other farm animals, that pre and post slaughter conditions must be adapted to take their unique characteristics into account. A small change in slaughter practice can have a mayor impact on the end product. Information acquired from these and future research should be disseminated to the farmers, producers and specific abattoirs that apply to special slaughter facilities and management for chevon production.

.Development of the market for chevon in South Africa would offer more diversity of species for red meat producers and especially benefit emerging farmers who produce over 90% of the goats in South Africa. There are good indications that goats can yield chevon or kid of acceptable quality to consumers, providing that animals of an appropriate age and sex group are slaughtered, handled and fed well during production and slaughter so as to minimise stress and prevent cold shortening.

Popular Article

Karkaskwaliteit/opbrengs van intakte en gekastreerde Boerbok en groot raam inheemse eco-tiepe veld bokke (sg. Noord-Kaap Spikkel en Oos-Kaap Xhosa (IVB) bokke)

Dr Lorinda Frylinck, Senior Navorser, LNR-Diere Produksie, Irene.

Veertig gespeende Boer en veertig IVB bokkies, waarvan 20 elk gekastreerde en intakte rammetjies was is in die krale van die Landbounavorsingsraad-Diere Produksie, Irene grootgemaak. Hulle is dieselfde dieet gevoer nl. “Ram, Lam en Ooi” pille, lucerne, hooi en natuurlike gras totdat ‘n gemiddelde lewendige massas van ongeveer 35 kg bereik het (lam ouderdom/0 permanente tande). Die gekastreerde IVB bokke was gemiddeld 1 kg ligter as die ander diere.

Hierna is hul geslag en die karkasse is oornag in ‘n koelkas van ongeveer 4°C geplaas. Buiten die warm karkasmassas, is die verdere karkaskwaliteitsmetings die volgende dag geneem. Die koue karkasmassas was tussen 14 to 16 kg en daar was ‘n warm tot koue karkasmassa verskil van ongeveer 3.5%. Die uitslag % vir die gekastreerde diere (BB en IVB)(44.5%) wat ongeveer 2.5% hoër was as die van die intakte rammetjies (42.0%). Ons het die sogenaamde vyfde kwart nie bestudeer nie.

Oogspier omtrekke gemeet in mm2 van die intakte ramme van beide die BB en IVB het nie verskil nie, maar die gekastreerde BB se omtrekke was effens groter end die van die gekastreerde IVB was effens kleiner – te wagte a.g.v. die kleiner karkasse.

Die karkasse is in die volgende kommersiele snitte verdeel en geweeg: nek, dikrib, lies, blad, bors, lende, kruis, boud en skenkel. Elkeen van hierdie snitte is weer gedisekteer om die % been, % sigbare vet en % vleis vir elke snit te bepaal. Verskille wat uitgestaan het tussen die 4 proefgroepe is die hoër nek % en dikrib % van die gekastreerde BB, die groter % lies by die BB oor die algemeen en die hoër % lende en boud van die gekastreerde IVB. Die % kruis van die gekastreerde diere was effens hoër invergelyking met die intakte diere.

Uit bogenoemde massas is die % vleis, % been en % sigbare vet (insluitend onderhuidse vet) per karkas bereken. Verstaanbaar het die intakte ram karkasse ‘n 1 tot 2 % hoër been persentasie van ongeveer 23% gehad teenoor die van 22% van die gekastreerdes. Die gekastreerdes het weer ‘n 2 tot 4% hoër totale vet % gehad van 9 to 10% teenoor die van die intakte ram karkasse van 6% vir die IVB en 8% vir die BB. Teenoorgestelde is weer gevind dat intakte IVB ram karkasse ongeveer 1% meer vleis (71% van die karkasmassa) gehad het invergelyking met die van die BB karkasse (69% van die karkasmassa) en die gekastreerde IVB ‘n karkasvleis % van 67% gehad het. Niere en niervet is ook geweeg. Niervet (kg) in al die gekastreerde karkasse (0.4 kg) was meer as die van die intakte ram karkasse van ongeveer (0.3 kg).

Dit lyk asof IVB nie so goed reageer op kastrasie nie omdat hulle so effens ligter was as die ander toetsgroeps en verdere studies hieromtrent is nodig. Hierdie kan ook dalk toegeskryf word aan kompetisie vir kos en kompeterende diere behoort alpart gehou te word. Tog lyk dit nie of dit die gekastreerde Boerbokke gepla het nie. Die uitslag persentasies het egter nie verskil tussen die gekastreerde rasse nie en was effens hoër as die van die intakte ramme, hoofsaaklik a.g.v. hoër % sigbare vet.Daar was nie noemenswaardige verskille in die % vleis tussen die rasse nie. Die groottes van die verskillende snitte verskil a.g.v. bouvorm en dit is genotipies te wagte, maar oor die algemeen gee die Boerbok en groot raam Inheemse Veld Bokke dieselfde tiepe opbrengs onder dieselfde produksie omstandighede.

Hierdie studie is deel van ‘n groter projek wat deur die Rooi Vleis Navorsings en Ontwikkeling SA (verteenwoordiger van die rooivleisbedryf) en Landbounavorsingsraad befonds word.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Lorinda Frylinck on lorinda@arc.agric.za

Formal and Informal Red Meat Industry in the Western Cape

Hidden in Plain Sight: A Regional Inquiry into the Size, Scope and Socioeconomic Effects of the Western Cape’s Formal and Informal Red Meat Industries

Industry Sector: Cattle and Small Stock

Research Focus Areas: Animal Health and Welfare; Animal Products, quality and safety, nutritional value and preference; The economics of red meat consumption and production in South Africa

Research Institute: Agriculture Research Institute – Animal Production Institute

Researcher: Dr Nick Vink PhD (Agric)

Title Initials Surname Highest Qualification
Mr. Michael McCullough M

Completion Date : 2018

Aims Of The Project

  • 3.1 To determine and report the size and scope of the informal red meat I industry as well as the informal industry’s effects on food safety, animal health and l welfare and food security with an initial focus on the Western Cape.
  • 3.2 To determine and report the size and scope of the formal red meat industry as well as the formal industry’s effects on food safety, animal welfare and food security with a primary focus on the Western Cape.
  • 3.3 To create and test a combined quantitative and qualitative methodology for determining the size and scope of the red meat industry in South Africa with a primary emphasis on the informal sector, a secondary emphasis on the formal sector as well as recommendations for improving current levels of food safety, animal welfare and food security.

Executive Summary

Hidden in Plain Sight

The genesis of Hidden in Plain Sight was two previous studies of red meat marketing systems: one in a rural Municipality in the Western Cape that discovered an informal shadow industry operating alongside a formal system of abattoirs, supermarkets and independent butcheries; the other in the townships and informal settlements of Cape Town that described an informal marketing system filling a vacuum created by the abdication of the formal system of supermarkets and butcheries. Beyond the scope of both studies was an appreciation of the size and scope of the Province’s informal systems of red meat production, processing and distribution. Hidden in Plain Sight attempts to determine size and scope of the Province’s informal red meat industry, its effects on food security, food safety and animal health and welfare.

Informal livestock farmers pasturing cattle and sheep primarily on Municipal land as well as raising pigs in improvised piggeries furnish livestock for informal processing; i.e. outdoor slaughter and indoor butchery in unlicensed facilities such as home kitchens and food stands. One and two kilo ‘value packs’ are then sold from kitchen butcheries in rural communities. Braai stands located near taxi ranks, train stations and major intersection in the former townships of Khayelitsha, Gugulethu and Nyanga in the Cape Town Metropole receive live animals directly from informal producers located on City land surrounding these communities. The animals are slaughtered on the sidewalk in front the stands or in any other adjacent open space. The muscle meat is sliced into strips and braaied, the heads are skinned, split and charred and the offal is piled on the counter for sale to hawkers or take-home consumers.

The informal system exists in both urban and rural areas to serve the 2.6 million low to very low income households in the Western Cape. In addition to low incomes many urban and rural households live in virtual ‘food deserts’ where, in the absence of transportation either public or private access to food sellers is at best difficult.  Low to very low incomes and lack of access expose over half of the Province’s households to food insecurity and place 29 percent at risk of hunger.

An expectation at the inception of this study was that size and scope of the informal system although unknown would rival the formal red meat system and would be sufficient to serve a significant percentage of the Province’s food insecure households. Such was not the case. Survey data based on inspections of informal production sites throughout the Province, census  and interview data from the Veterinary Service and the Farmer Support and Development programmes of the Western Cape Department of Agriculture and interviews with Municipal Social Development officials yield numbers of informal produced livestock clearly insufficient to serve a fraction of households at risk for hunger. Three recommendations are offered to increase the capacity of the informal industry to serve food insecure households: conduct a comprehensive inventory of public land suitable for informal production; establish an informal production, processing and distribution pilot project in each District Municipality; investigate existing parallel formal – informal marketing systems in Latin America; develop a prototype two tiered regulatory frame work to facilitate food security whilst ensuring food safety.

POPULAR ARTICLE

Magazine Article

Michael McCullough

When South African consumers walk into their local supermarket to shop for beef, lamb or pork they expect a fresh, high quality, attractively packaged, nutritious product and they get it. No need to worry about the safety of the product. South African cattle, sheep and pigs are given a through once over before they set foot in an abattoir. Any animal injured, unfit or suspected of disease is promptly rejected, condemned and disposed of. It’s not a business decision, it’s the law.

What supermarket shoppers are beginning to worry about is the possibility the meat they serve their family and friends could come from terrified, abused or injured animals. They want to know that the slaughter process is humane and animal suffering is minimised. That may sound like a contradiction in terms but it’s not. Here’s why:

  • After arrival at the abattoir animals must be rested for at least an hour. The animals must calm and ready for inspection just before they are taken into the abattoir.
  • After passing single file through a narrow corridor each animal is taken individually into a slaughter room and placed in a narrow box or a harness. This happens out of sight of the other animals to reduce stress on those queued up behind.
  • The actual killing must be painless. Animals are stunned with a strong but not fatal electric shock or with a captive bolt pistol that delivers a sharp blow to the animal’s forehead.
  • While the animal is unconscious both the arteries and veins in the neck must be severed quickly and accurately. Contrary to the movies where the victim drops dead just after his throat is cut; if one or more veins or arteries are missed the animal may take from a minute to five minutes to die. If the stun wears off before enough blood is lost to shut down the brain the animal can experience pain.
  • Stunning and wielding the knife is hard, skilled and dangerous work. Humane slaughter depends on workers who are alert and careful. Tired operators may become careless or insensitive to animals’ welfare therefore abattoirs insure their operators take regular rest periods to maintain their skills.

The animal’s carcase is then moved to a high ceilinged room and hoisted head down to finish the bleeding process. The carcase is now ready for butchery. For consumers preferring kosher or halal meat the procedure is slightly different. For kosher slaughter no stunning is allowed but to minimise suffering the arteries, veins, vagus nerve, trachea and oesophagus are severed in a single quick sweep of a very sharp knife. Halal abattoirs may elect to stun the animal. Properly done the animal is unconscious in three seconds because severing the vagus nerve is like shutting down the body’s neurological switchboard.  Flip the switch and the lights go out.

One thing consumers shopping at their neighbourhood supermarket or butchery don’t want to worry about is whether the chops and steaks they’re buying are safe to eat. Should they? After all nobody wants to have friends and family or even worse, their boss over for a braai and find out later that everyone wound up at the clinic with gastric ‘distress’ or worse. This threat is all but completely short-circuited by post slaughter meat inspections, cold chain management and strict hygiene practices from the abattoir to the wholesaler to your butcher to your shopping cart.  Here’s how it works:

  • After the carcase has bled out, the head and hide are removed taking care to make sure the hair side of the hide doesn’t touch the meat. After all the animal has never seen a shower stall so the hide is pretty grimy. For this reason anything that touches the hide shouldn’t touch the meat such as dirty hands, in in the low income housing areas next to most country towns and in densely populated urban communities like Khayelitsha in Cape Town implements, dirty hands or soiled protective clothing.
  • Organs like the gut and the gall bladder contain seriously infectious bacteria like salmonella so the viscera must come out intact (the viscera is the sack that contains digestive tract). If it splits like a cheap trash bag on the way out everything you don’t want to touch the meat goes everywhere including all over the carcase. Assuming everything comes out as planned it’s time for final butchering and trimming.
  • The carcases are halved, the spines removed, all the other inedible bits and pieces as well as any contaminated meat is cut out and discarded. The carcase is washed and chilled. The slaughter and butchering processes are done.

From here to your grill is just a matter of maintaining the cold chain – keeping the carcase clean and chilled — until it passes through the wholesaler’s cold storage on its way to your neighbourhood supermarket or butchery. The carcase is then cut into meal sized portions, wrapped, marked, priced and put in the display case. Done and dusted.

Just as every coin has two sides so does every industry. The meat industry is no exception. The formal, visible side of the industry serves the middle and upper classes and the informal, mostly invisible side serves everyone else.

When low to very low income consumers shop for beef, lamb or pork do they expect high quality and fancy packaging?  Do their questions about nutrition go much further than Will it satisfy my family’s hunger or not?  Does price matter more to this consumer than where the animal came from, what condition it was in and how did it die? It’s safe to say that putting enough affordable on the table comes first; nothing else really counts.

For these reasons a growing number of South Africans are turning away from supermarkets and butcheries to buy meat produced and processed in their own communities. Why are a growing number of consumers in low income urban communities bypassing abattoirs, supermarkets and butcheries?

Until recently not much was known about the informal red meat industry in the rural Western Cape. It was not completely invisible but rather operated in the shadows just out of sight of most supermarket and butchery shoppers.  Informal stock producers who supply this industry aren’t usually landowners and depend heavily on leased Municipal property adjacent to low income housing areas and shanty towns. Cattle and sheep producers graze their animals where they can find grass and water. However pig producers must confine their animals to keep them from roaming. They build pens from scraps of lumber, sheet metal or other discarded building materials. Pig can’t be kept just anywhere; they need a source of water for mud to wallow in during the warm months (they don’t sweat enough to keep cool). The smell of an informal pig kraal is unforgettable so most are located away from housing. Although neighbours don’t seem to mind cows or sheep wandering through the community they usually draw the line at somebody else’s pig rooting in their garden.

When an informal producer is ready kill a pig, for example he or she spreads the word and takes orders. When it comes time to slaughter the producer recruits several volunteers; puts a barrel or large pot of water to boil on a wood fire and brings the pig forth. The pig is stunned by one or more blows between the eyes with a heavy hammer. A long sharp knife is inserted to the hilt just above the breastbone, twisted vigorously and pulled out. If all goes well (and it sometimes doesn’t) the pig will bleed out rapidly. Unfortunately most informal sites don’t have a convenient tree to hoist the pig so that it bleeds out completely. It’s often left on the ground to ooze blood until the time seems right to dip the carcase into the hot water to loosen the hair and underlying membrane. After the hair is scraped off down to the white skin it’s time to remove the head, the viscera and the rest of the internal organs. The pig should be hung for a day and allowed to cool. In practice this seldom happens. A carcase hanging from a tree overnight is likely to attract unwanted attention from the authorities. So the carcase is immediately butchered into saleable portions, refrigerated or frozen if possible and sold to local consumers. The helpers are usually rewarded with a share of the meat, the head and the offal.

The routine for cattle and sheep is similar except for the extra volunteers needed to handle a 150 kg cow carcase. Cow hides are removed with a knife and sheep skins are pulled off by hand. Unlike a pig no boiling and scraping is necessary.  Contamination from faeces and urine is hard to avoid and accidents often occur when the processing crew is tugging the heavy, slippery viscera out of the gut cavity not to mention the near certainty of hair and dirt on the meat. The carcase is usually rinsed with water carried to the slaughter site in buckets.  Given the rough ad tumble nature of informal slaughter it’s surprising that reported cases of food poisoning from informally sourced red meat are so rare as to be non-existent.

In Khayelitsha, a large densely populated suburb of Cape Town the informal system is not only out of the shadows it’s out loud and proud. Next to every train station, taxi rank and surrounding every major street intersection sidewalk braai stands do a thriving business in grilled beef, pork and mutton. Tens of thousands of commuters stop by these stands every day to pick up a takeaway meal on the way to and from work. Think off these stands as fast food outlets for the black urban working class. Just like the ‘McWhatevers’ in other neighbourhoods      braai stands offer accessible and  affordable (but not necessarily inexpensive) meat to consumers without the means or time to buy meat fresh, take it home, refrigerate it and cook it later. The big difference between fast food outlets in neighbourhoods like Khayelitsha and outlets other less crowded and more affluent neighbourhoods is how the meat gets there and what happens when it arrives.

Live animals are brought in from surrounding communities and slaughtered on sidewalks in front of the stands, alleys behind the stands or any unoccupied space. A source of water to rinse the carcases is strictly optional. The muscle meat is sliced into strips and immediately grilled. The heads are skinned or scraped, split and charred for serving. The offal is piled on tables and sold to customers for home consumption.

To outsiders the scene is a bloody, chaotic and cruel public health disaster. Are there issues with quality? Yes. Nutrition? Absolutely. Packaging? Of course. Safety? Afraid so. Access? No. Affordability? No. To Khayelitsha residents braai stands are a local informal industry that meets their community’s needs because the formal industry is either unwilling or unable to do so.

So which consumer model makes will prevail? The supermarket model that creates expectations of quality, safety and nutrition wrapped up in attractive packaging but comes at a high price? Or the braai stand/informal butchery next door that makes up for little or no packaging, no guarantees of quality, safety or nutrition but delivers affordable prices and accessibility?

For the foreseeable future the answer is both. Consumers who are willing and able to pay a price premium for the value added by abattoirs, wholesalers and supermarkets in exchange for guarantees of quality, safety and nutrition will continue to do so because they can. Consumers who lack the means to pay for those kinds of guarantees and who must take their chances in return for accessible and affordable meat will continue to do so because they must.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Dr Nick Vink  on nv@sun.ac.za

Chilling and electrical stimulation of beef carcasses

Effects of chilling and electrical stimulation on carcass and meat quality attributes of selected breeds of cattle with different carcass weights

Industry Sector: Cattle and Small Stock

Research Focus Area: Animal Products, Quality and Value-adding

Research Institute: University of Pretoria

Researcher: Prof Edward Webb

Title Initials Surname Highest Qualification
Mr Babatunde Agbeniga MSc
Dr P.E. Strydom PhD

Year of completion : 2018

Aims Of The Project

  • To compile a comprehensive literature review on current chilling and electrical stimulation guidelines
  • To compare chilling and electrical stimulation of selected cattle breeds of different carcass weights and to evaluate the effects of different chilling regimes and different stimulation procedures on carcass and meat quality attributes
  • To make recommendations to the meat industry on acceptable ways of chilling and stimulating carcasses in order to obtain the best quality carcasses and meat

Executive Summary

This research focused on acceptable ways of chilling and electrically stimulating beef carcasses in order to obtain the best quality meat, given the current use of growth enhancing molecules (beta-adrenergic agonists) and the current increase in carcasses size to curve the negative impact of escalating maize prices on the economics of intensive feed of beef cattle.

The literature survey suggest that low voltage electrical stimulation (LVES) is safer and more practical in South African abattoirs compared to high voltage electrical stimulation (HVES). The current research indicates that low voltage electrical stimulation has beneficial effects on meat quality of beef carcasses. Furthermore, early post mortem LVES is more beneficial compared to LVES after evisceration in terms of most meat quality attributes. Shorter duration LVES (30 sec.) was more beneficial compared to long duration LVES (60 sec.). Current chilling regimes of larger carcasses demonstrate that the effects of beta-agonist treatment on beef tenderness becomes negligible with increasing carcass size, provided that such carcasses are electrically stimulated early post mortem. Optimum carcass stimulation and chilling regimes were proposed for commercial beef abattoirs in South Africa.

OUTPUTS

Scientific publications (ISI peer reviewed)

  1. Agbeniga, B. & Webb, E.C. (2018). Influence of carcass weight on meat quality of commercial feedlot steers with similar feedlot, slaughter and post-mortem management, Food Research International, 105,793-800. (IF=3,086)
  2. Agbeniga, B. & Webb, E.C. (2018). Effects of timing and duration of low voltage electrical stimulation on selected meat quality characteristics of light and heavy bovine carcasses, Animal Production Science, (Accepted with minor changes).

Scientific conferences

  1.  B. Agbeniga, E.C. Webb, P.E. Strydom & L Frylinck, 2016. Effects of low voltage electrical stimulation and carcass size on meat tenderness and drip loss of beef carcasses treated with Zilmax®, 49th SASAS Congress, Cape Town, (Oral presentation).
  2. B. Agbeniga & E.C. Webb, 2015. Effects of duration of electrical stimulation and carcass weight on carcass pH, temperature profile and shear force of Zilmax treated beef carcasses, 48th SASAS congress, Zululand, (Oral Presentation).

Industry lectures

  1. Webb, E.C. (2016) Growth enhancers, residues and beef quality, Red Meat Abattoir Association Conference, Spier, Western Cape,
  2. Webb, E.C. (2016) Abattoir management and carcass and beef quality, Devon abattoir workshop, Protea Hotel, 22 July 2016.
  3. Webb, E.C. (2015). Factors that affect beef carcass and meat quality, North West RPO Koopmansfontein,  October 2015.
  1. Webb, E.C. (2015).Growth efficiency in feedlot cattle, Cattleman’s conference, South African Feedlot Association, March, Kiewietskroon.

Popular Article

Interactions between early and delayed electrical stimulation and carcass size on pH, temperature decline and instrumental shear force of meat samples from Zilmax treated cattle

Introduction

The time of application and duration of electrical stimulation (ES) on light and heavy carcasses from Zilmax treated animals, poses new challenges in the meat processing industry in South Africa. Owing to the use of Zilmax, larger carcasses are now being processed at abattoirs that were built to accommodate smaller carcasses. This poses new challenges in terms of optimization of conversion of muscle to meat using ES and appropriate chilling regime. In this study, the effects of early or delayed low voltage electrical stimulation (LVES) (110V) applied to light and heavy carcasses of Zilmax treated cattle were evaluated for pH and temperature decline, and the resultant effects on instrumental shear force. One hundred and forty-nine Zilmax treated cattle (mainly steers) were assigned to 10 different treatment groups according to the combination of their carcass weight (≤ 130 or ≥ 145kg side), time of stimulation (early stimulation-3 min post mortem [p.m.] or late stimulation-45 min p.m.), and the duration of stimulation (30 or 60 sec). Analysis revealed significantly (p < 0.05) faster pH decline and the lowest pH in carcasses stimulated before evisceration, at all times of measurement compared to carcasses stimulated late or non-stimulated controls. The time of ES application exerted the greatest influence on the pH profile while duration of stimulation showed minor influence. Heavy carcasses in the early stimulated groups had the lowest rigor- and ultimate pH. Regarding temperature decline, heavy carcasses had the slowest decline (p < 0.05) and the highest carcass temperatures at all times from 45 min to 24 hr p.m. Time of ES application and duration of ES did not affect carcass temperature. In terms of shear force, carcasses stimulated at 3 min p.m. had the lowest (p < 0.05) shear force at 3 and 14 days p.m. compared to carcasses stimulated at 45 min p.m. and controls respectively. Heavy carcass groups, stimulated early, with the lowest rigor and pHu, had the lowest shear force at 3 and 14 days p.m.

Effects of electrical stimulation and chilling on beef quality

Results of our recent study indicates that the time of application of electrical stimulation has an important influence on carcass pH and temperature profile, and in combination with carcass weight, has a large influence on the tenderness of beef. LVES provides a practical way to manipulate glycolysis in order to improve beef tenderness, but it appears that this treatment should be applied early post mortem in ordser to be efficient. Although there has been some suggestions to apply LVES later, the present results show that early post mortem application of LVES produced the lowest shear force, mainly due faster pH decline in combination with high initial carcass temperature.

Previous research suggested that at high muscle temperature combined with low pH, heat shortening may occur, leading to lower beef tenderness. Our results indicate that LVES treatment early post mortem passed through the heat shortening window (above 350C) within 2 hr p.m. when the pH was less than 6. This finding clearly demonstrates that the proteolytic activity was not exhausted by the low pH and elevated initial temperature in the early stimulated carcasses.

Carcass weight also played a part in improving tenderness in the early stimulated carcasses. In addition, Zilmax is known to reduce tenderness in meat but the application of ES could improve tenderness by the early activation of the calpain system. It is important to note that ES-treatment improve but do not completely overcome the negative effects of Zilmax on tenderness. In this study, we found that the combination of early ES and carcass weight significantly lowered the shear force in the heavy carcass groups. Research by Webb and Morris on Zilmax treated cattle also show that heavier carcasses from zilmax treated cattle produced more tender meat.

On the other hand, carcasses stimulated late and the controls had slower pH decline at all times of measurement, which was also reflected in lower tenderness scores at both day 3 and 14 post mortem.

Results on the duration of electrical stimulation indicates that 30 seconds or less (15 seconds) provide most beneficial results, which agrees with a number of other international studies.

Conclusion

It is concluded that the application of low voltage electrical stimulation early p.m (3 min p.m) brought about a significantly (p < 0.05) lower shear force in carcasses from Zilmax treated cattle compared to the ones stimulated late (45 min p.m) and the un-stimulated controls. Heavy carcasses (≥ 145kg) from the early stimulated groups had the lowest shear force values at 3 and 14 days p.m despite passing through the heat shortening window, which was due to lower initial pH and higher initial muscle temperature. More proteolytic activity in the heavy carcass groups was suspected to have contributed to the low shear force values and although, slightly higher (at 5.6 and 5.9 kg) when considering a threshold of 4.9 (Shorthose et al., 1986). It is acceptable, considering the fact that the animals were treated with Zilmax which is known to reduce tenderness.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Prof Edward Webb on edward.webb@up.ac.za

Effects of growth enhancers on residues in lamb

The effects of steroidal growth implants and β- adrenergic agonist, alone, or in combination on feedlot performance and residues in lamb

Industry Sector: Cattle and Small Stock

Research Focus Area: Animal Products, Quality and Value-adding

Research Institute: University of Pretoria

Researcher: Prof Edward Webb

Title Initials Surname Highest Qualification
Dr A.L. Le Riche BVSc, MScAgric
Dr Shaun Morris BVSc(Hons), MScAgric

Year of completion : 2017

Aims Of The Project

  • To investigate the feedlot performance of feedlot lambs treated with different steroidal growth implants, alone or in combination with oral beta-agonist supplementation
  • To investigate the effects of different steroidal growth implants, alone or in combination with oral beta-agonist supplementation on the residues in the meat
  • To investigate the effects of different steroidal growth implants, alone or in combination with oral beta-agonist supplementation on carcass and meat quality

Executive Summary

The objective of this study was to compare four commonly used growth promotants in a commercial sheep feedlot. The steroidal growth promotants chosen for this trial were Ralgro (zeranol), Revalor G (Rev G; TBA/oestrogen- 17β), Revalor H (Rev H; TBA/oestrogen- 17β) and Zilmax® (zilpaterol hydrochloride). The growth promotants were compared with one another and within three sex groups, namely ewe, ram and wether (castrates), to determine which molecule or combination of molecules, if any, had the most benefit and profitability when measured against a control group.  Sheep were stratified based on initial weights and then randomly allocated to treatment groups in a completely randomised control study. All sheep originated from the same farm, and they were of  similar age, breed,  transport method,  processing method, feed ( the only difference being  the groups receiving Zilmax® during the last 18 days of feeding, making provision for 3 days withdrawal), weather conditions, housing and time on feed. A time constant termination date was used in this study, in order to measure the performance of lambs in treatment groups over time.

The experimental groups were compared over a 10 weeks feeding period according to growth and carcass parameters. The parameters that were measured were gain, FI (feed intake), FCR (feed conversion ratio), ADG (average daily gain), WCM (warm carcass mass), DP (dressing percentage), CL (carcass length) and CC (carcass compactness). Data was recorded in an Excel spread sheet and checked for accuracy. The effect of experimental treatments on growth and production parameters were analysed by means of the GLM ANOVA procedure in SAS (2006). Differences between treatment means were tested at the P<0,05 level of significance by means of the Bonferroni multiple range test in order to correct for unbalanced data (missing values). Correlations between variables were analysed by means of the Pearson product moment procedure in SAS.

Data was analysed within weeks, treatment phases and also over the entire experimental period. Effects of sex, steroid treatment and beta-agonist treatment and interaction effects were calculated. In terms of growth and slaughter parameters the use of zilpaterol hydrochloride alone proved most effective. The latter can be explained by the repartitioning effect of the BAR which increased protein accretion as a result. Benefits gained were not always statistically significant, however taking cost of treatment into account, there is a definite financial significance when choosing which combination of growth promotants to use. Muscle and liver samples were collected for residue analyses, which indicated no significant residue’s in any of the treatment groups. The current data indicate that the use of the various combinations of growth enhancing molecules in sheep pose no risk to consumers in terms of the presence of residue’s, provided that the molecules are used according to prescribed procedures and dosages.

Popular Article

In South-Africa, the finishing of cattle in a feedlot, has, over many years, become part of the value chain of marketing beef. Huge amounts of money have been made available for research to find the most cost-effective ways of producing high-quality beef (Le Riche, 2014). Relatively little research in intensive, sheep production for South-African conditions has been done up to now, leaving a number of questions regarding the safe use of certain growth-promoting agents.

Traditionally sheep were finished extensively on the veld as this was thought to be the least expensive option. Alternatively, farmers bought in lambs from others who did not have enough grazing and finished them on harvested corn fields. This is also an inexpensive option as the corn residues are readily available after harvesting. These practises, however, give rise to seasonable availability of lambs with resultant huge fluctuations in lamb meat prices. Furthermore, the national sheep herd has decreased significantly over the last decade. There are various reasons for this. Drought and the resulting reduction in grazing, being one, and the substantial stock losses due to theft and predators, to name but two, being another (Mokolo, 2011).

Whenever a product is in short supply its price escalates. As a result of this, lamb has become an expensive. There, however, remains a HUGE demand for lamb as it constitutes a major source of protein for a significant part of South-Africa’s population. The constant production of lamb, that meets market specifications has thus become more and more important (Buttry & Dawson, 1990).  In an effort to make lamb more readily and constantly available and also more affordable, lamb feedlotting is increasingly being used as a method for increasing the amount of meat being produced. Due to the current high cost of feed and the labour intensive nature of such ventures, the profit margin of a sheep feedlot can be very small.

At the present time it costs about R 326.00 to FINISH a lamb that is market ready within 70 days, (cost of the lamb excluded) (Le Riche, 2014). The total profit made on such a lamb after all production costs have been deducted could be as little as R24 – 00. The profit margin is dependent on the meat: feed price ratio. In an article by Voermol Feeds (2010) it is stated that feed conversion ratio is considered to be the critical aspect of feedlot profitability. Any reduction in feed intake or increase in feed efficiency, without compromising carcass quality, is economically important (Snowder & Van Vleck, 2003)  Thus the lamb that converts feed the best (in other words the lamb that produces the most kilograms of meat, per kilogram of feed consumed), is the most profitable lamb. One could say that , an increase in profits constitutes a decrease in input cost and/or an increase in production output. Cost of feed is an important input cost, whilst growth rate and carcass composition is an important production output (Buttry & Dawson, 1990; Snowder & Van Vleck, 2003).

There is a need to balance more efficient food production, with positive public perception. This has become a great challenge. Professionals in the industry have to determine which products and methods could be optimally used to the benefit of the producers, without gaining negative opinions from the public sector and it  has to go hand in hand with maintaining a high level of consumer safety (Buttry & Dawson, 1990).

Optimal feeding conditions that promote high voluntary intake, added to a high quality, properly balanced ration should promote profitability. The high cost of quality feed is, however, making it even more important to research the responsible, effective use of different types of growth promoting agents, alone or in combination. These products have the potential to:  1) produce animals with a higher meat: fat ratio; 2) to keep the feeding time down to a minimum and to thus reduce the impact on the environment; 3) to increase the ability to supply the protein needs of an ever-growing population.

The use of BAR agonists in ruminant production animals as a growth ENHANCER has been the subject of many heated debates and much media publicity. The reason for this is the very real potential that some of these products, clenbuterol, to name one, can have serious toxic effects in human consumers. (Stachel et al., 2003). BAR agonists used as growth promoting agents, work on the basis that they reduce body fat whilst increasing muscle hypertrophy, without causing significant alterations in organ and bone mass. They are therefore also known as repartitioning agents (Beermann, 2002). Repartitioning literally means the channelling of energy away from storage cells in the liver and adipose tissue towards muscle tissue. The sensitivity of liver and adipose tissue towards insulin is lessened whilst it is increased in muscle tissue (Beermann, 2002).

Their pharmacological action leads to an improved ADG, improved gain efficiency (G: F) and increased hot carcass weight in both feedlot beef and lambs (Reeds, 1991; Beermann, 2002; Estrada-Angulo, et al., 2008). This effect is seen with no SUBSTANTIAL increase in daily DMI.

When age comparison studies were carried out, maturity of muscle tissues proved to be a critical factor with regards to efficacy .It would then make sense that receptor presence and availability would be important in the physiological effect of this drug as mature muscle would have a higher density of receptors available (Beerman, 2002). The lack of response or reduced response in young animals would also act as proof that young muscle fibres lack enough Beta adrenergic receptors, according to Beerman, (2002).

BAR agonists, such as Zilmax® function by stimulating mainly β2- AR. This causes muscle hypertrophy and hyperplasia, lipolysis and reduced lypogenesis as well as the indirect effect of lowered insulin sensitivity. According to Baxa et.al. (2010), it does have beneficial effects to treat animals with anabolic steroid implants first, following with the oral application of ZH. Cattle that received this combination treatment showed additive improvements to lean carcass mass and performance, such as ADG and FCR.

Growth enhancers such as hormonal implants and repartitioning agents such as zilpaterol hydrochloride  are used in intensive production systems to reduce the cost of production by decreasing the feeding time, improving feed conversion and increasing the carcass slaughter weight (Pritchard, 1998; Duckett & Andrae, 2001).This should prove to be true for both cattle and sheep feedlots. According to Casey (1998) the efficacy of β- receptor agonists are determined by the relationship between the chemical structure of the compound, the theoretical number of receptors that need to be stimulated to elicit a response and the resultant effect when the β2 receptors are stimulated.

Conclusions

In sheep the best reaction is obtained when Zilmax® is fed during the last 18 – 25 days (usually 21 days) of finishing, leaving time for a three day withdrawal period before slaughter. Previous studies indicate that a minimum of 48 hours was necessary in cattle, to reach a minimal residual level. It can be expected that sheep would generally react in the same manner. At present, the acceptable dosage for ruminants is 0.15 mg/kg/day which cconstitutesa dosage of 70 g/ ton of feed in sheep.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Prof Edward Webb on edward.webb@up.ac.za

Genetic study on wet carcass syndrome

Detection of quantitative trait loci affecting wet carcass syndrome in sheep

Industry Sector: Cattle and Small Stock

Research focus area: Animal Products, Quality and Value-adding

Research Institute: Agricultural Research Council – Animal Production Institute

Researcher: Lené van der Westhuizen

Title Initials Surname Highest Qualification
Prof M.D. MacNeil Ph.D.
Prof M.M. Scholtz D.Sc.
Prof M.D. MacNeil Ph.D.
Prof F.W.C. Neser Ph.D.
Prof A. Maiwashe Ph.D.
Mrs A. Theunissen M.Sc.
Ms M. le Roux M.Sc.

Year of completion : 2018

Aims of the project

  • To map quantitative trait loci affecting wet carcass syndrome.
  • To identify specific loci affecting the predisposition to wet carcass syndrome (detection of a major gene).
  • To develop a diagnostic test for the genetic predisposition to wet carcass syndrome (if a candidate gene can be identified as the cause).
  • If a major gene is not responsible for wet carcass syndrome the second phase of the project will have the aim to develop a polygenic prediction equation for the predisposition of sheep to wet carcass syndrome.

Executive Summary

Wet carcass syndrome (WCS) is a condition predominantly found in sheep, which negatively affects the quality of their carcasses. During the pre-slaughter period, the animal appears to be clinically normal, showing no symptoms of an abnormality. However, after the removal of the skin during the slaughter process the carcass appears to be “wet”. When the description and results of prior research are taken into account, no physiological, environmental or management system was conclusively identified as the causative agent of WCS. Previous research has also not considered a potential genetic basis for WCS or the potential for an interaction of genotype with the environment (stress). Furthermore, the tentative breed-specificity, i.e. Dorper sheep breed, of the condition lends some credence to a potential genetic basis for it. The current study employed the Ovine Infinium® HD SNP BeadChip and a genome-wide association analysis approach to scan the genomes of both afflicted- and unafflicted sheep in search of putative quantitative trait loci associated with the WCS phenotype. This study was not only one of the first in Southern Africa to make use of this specific BeadChip but also the first to investigate the role of genetics as a causative factor of WCS. Muscle samples from sheep carcasses (33 afflicted and 36 unafflicted) were collected from three different abattoirs.

Using a candidate gene approach it was possible to map genetic loci, RYR1 (Chromosome 14) and PRKAG3 (RN¯; Chromosome two) causative of phenotypically similar conditions such as porcine stress syndrome and red, soft and exudative meat to the ovine genome, respectively. The positions of these loci mapped to the ovine genome were not in accordance with the loci showing significant association with the WCS phenotype; and no relationship was found between single nucleotide polymorphisms located within these genes and WCS. Furthermore, along with the latter approach, the test of runs of homozygosity presented similar results as well as providing plausible evidence that WCS is not a recessive inherited condition.

To test for an association between the phenotype (WCS) and a genetic marker(s) i.e. SNPs, a case-control study design was implemented. Given the relatively small sample size of the current study, the results obtained from the GWAS attested strong evidence of at least two loci, oar3_OARX_29903534 and oar3_OARX_113973214 positioned within the non-homologous region of the X chromosome for WCS carcasses. All afflicted animals, both males and females, carried at least one allele for marker oar3_OARX_113973214, which was shown to be related to the WCS phenotype. On the contrary, some of the unafflicted animals also carried this specific allele.  Given the apparent influence of stress on WCS, these unafflicted males and females in all likelihood did not experience adequate levels of stress to manifest the condition post-slaughter. The results of the current study also indicated that WCS may possibly be a rare X-linked inherited condition, provided only female individuals are considered. Finally, two possible major loci involving two major genes, HTR2C and DMD, positioned on the non-homologous region of the X chromosome have been identified as novel positional and functional candidate genes for WCS in sheep.

Popular Article

Wet carcass syndrome (WCS) is a condition mainly found in sheep, which negatively affects the quality of their carcasses. It has been identified in both sheep and cattle breeds, however, the frequency of WCS seen in cattle is substantially less than in sheep. Despite long-standing knowledge of the condition and research, little more is known about wet carcass syndrome and its causes than when it was discovered some three decades ago. Furthermore, it is very difficult to simulate the condition and in some years it is almost absent. Possible causing factors of WCS included the over-hydration of thirsty sheep on arrival at abattoirs, transport distances to abattoirs, allergies, compulsory dip, washing of carcasses in abattoirs under high pressure, condensation in coolers and provision of feed blocks during the pre-slaughter phase.

However, research could not find any link between these factors and the occurrence of WCS. Therefore, when the description and results of prior research are taken into account, no physiological-, environmental- or management system was conclusively identified as the causative agent of WCS. However, stress experienced by the animals during the pre-slaughter period has been identified as a possible contributing factor. Some prevention strategies have been proposed, but the problem still appears from time to time and is more severe in some years.

Wet carcass syndrome is mainly observed in hairy-type Dorper sheep and crosses of Dorper with indigenous and locally developed breeds of South Africa and Namibia, and largely seen in A0 / A1 carcasses (very low fat content with poor conformation). The Dorper breed is greatest in numbers in the studied areas (geographic regions where WCS occurs most frequently) of the Northern Cape Province in South Africa and the southern part of Namibia (Kalahari dunes and sandy veld). Unofficial slaughter statistics from WCS afflicted areas, reveal that certain abattoirs have higher numbers of WCS carcasses, whereas other abattoirs in the same region will have no recorded incidences. Communication between the researcher and abattoir management exposed the seriousness of the condition to communities in the Northern Cape. The condition is found widespread across areas where the grazing quality is poor, although the quantity is often abundant. WCS is also more frequently observed during autumn and winter, especially after droughts or after periods of above-average rainfall during spring, followed by low rainfall during the rest of summer.

During the pre-slaughter period, the animal appears to be physically normal, showing no symptoms of an abnormality. However, after the removal of the skin during the slaughter process, the carcass appears to be “wet”. An uncoloured, slightly sticky, jellylike fluid gives the carcass the shiny and wet appearance. The areas most affected on the carcass are the brisket, flanks, hindquarters, sides, and back. Affected carcasses do not dry off with overnight cooling. Consequently, WCS carcasses are not accepted, with two of the main reasons being appearance and a reduced shelf life. The most sensible explanation for the reduced shelf life is that the surface of the meat is a favourable environment for the growth of microorganisms. In addition, there is an occupational hazard associated with cutting wet carcasses in that a band saw pulls more on the meat which may result in injury to the operator. These observations further illustrate how potentially detrimental WCS is to the sheep meat industry in South Africa.

Lamb producers are very concerned about this condition and are actively participating in research to find solutions for this condition and to identify management procedures to alleviate their economic losses which may collectively rise to 10’s of millions of Rand annually. Carcasses that show WCS characteristics are generally rejected at the abattoir and not sold for human consumption. Taking carcass prices and inflation into account, the loss due to WCS can be estimated at a minimum of R 45,696,774 and during 2010 alone at R 27,010,387.

The literature review showed both promising results in terms of research opportunities and the identification of possible candidate genes for WCS. These candidate genes are the ‘genetic foundation’ of animals that will produce meat with characteristics of being pale, soft and exudative- (PSE); red, soft and exudative- (RSE) and dark, firm and dry (DFD) meat. These conditions are primarily observed in pork meat, but show phenotypic (visual) characteristics that are similar to WCS. All three of these meat characteristics are ‘trigged’ by stress. PSE/RSE meat will be the result of short term stress. Short term stress will cause a rapid decline of glycogen reserves within the muscle and finally result in meat with a low pH. The opposite occurs with DFD which is caused by long term stress. Long term stress causes severe muscle glycogen depletion, which in return causes the meat to have higher than normal pH levels. Selecting swine for leaner and heavier muscles resulted in some animals having greater susceptibility to stress and meat that is of poor quality. High vulnerability to stress in pigs is today referred to as porcine stress syndrome (PSS), and results in PSE meat. PSS can be described as acute death caused by stressors such as exercise, fighting, high temperatures, birth, stocking density, loading, transport, overcrowding at abattoirs, the use of electric prodders and abuse.

From a genetics perspective, PSS and RSE are caused by mutations within genes. PSS is caused by a single recessive inherited gene, ryanodine receptor 1 (RYR1), located on Chromosome 6 of the pig genome. There have been reports on PSE meat in other species including cattle, ostriches, turkeys and chickens. The Rendement Napole (RN¯) gene is a dominant inherited gene and located on Chromosome 15 of the pig genome and will result in RSE meat. RSE meat will result in meat having a high drip loss.

The most recent research, finished in 2018, was the first study to examine the role of genetics as the leading cause of WCS. Three scientific methods were used to identify regions within the sheep genome that may contribute to the development of WCS. These methods are termed comparative genomics using candidate genes, runs of homozygosity (ROH) and a genome-wide association (GWAS) using a case-control study design. The first two methods did not provide the research team with any positive results. Firstly, the mutations within genes causing PSS and RSE in pigs most likely do not cause WCS. Secondly, an individual with identical long stretches of DNA that are inherited from parent lines is called runs of homozygosity. The research team searched for these ROH within the DNA of WCS affected carcass, but could not find any positive results.

The final phase of the study, i.e. GWAS, compared the DNA of both affected (WCS) and unaffected (normal) carcasses in search of DNA markers, named single nucleotide polymorphisms (SNPs), that might be associated with the WCS phenotype. When using the GWAS methods, an SNP will be associated with the condition when this specific genotype (genetic make-up of the animal) is more common in affected- than in unaffected carcasses. The results from this part of the study however, provided strong positive results that at least two of these DNA markers positioned on the X chromosome of the affected carcasses are most likely associated with WCS. However, these DNA markers were also found within the genotype of some of the unaffected or normal carcasses. Now to summarize the important results, some sheep carcasses that were normal also carried the same DNA markers than WCS affected carcasses. One possible explanation could be that these unaffected animals did not experience high enough levels of stress before slaughter to cause the WCS condition after slaughter.

These two DNA markers that were identified by the research team were then further linked to two genes, 5-hydroxytryptamine (serotonin) receptor 2C (HTR2C) and Duchenne muscular dystrophy (DMD). As a result, these two genes were identified as candidate genes for WCS. Many biological functions of these genes exist, however, only a few functions could be connected to WCS. Assuming the HTR2C gene causes WCS, a disruption in cell homeostasis will occur, either during before the slaughter process by means of stress and anxiety; or after the slaughter period has been completed, through the calcium ion homeostasis mechanism within the cells of WCS affected muscles. Similarly, assuming the DMD gene causes WCS, the phenotype could be due to an increase in porousness of the cell membranes of muscles causing the typical shiny wet appearance of WCS. A novel or new porcine stress syndrome was, also identified in 2012 that is also caused by the DMD gene. Both of these genes explained in more modest words, will cause the cells within the muscle to act abnormally and fluid will move out from the cells onto the surface of WCS carcasses. However, this is only a theory and the precise biological mechanism causing WCS is presently unknown.

Future studies will first attempt to determine the exact position of the DNA marker(s) that cause WCS. Under the condition that WCS is caused by a single mutation, the development of a diagnostic test to identify live carrier animals of wet carcass syndrome, will enable sheep farmers to use this information in an attempt to eradicate the condition from their flocks. It is entirely possible that previous research attempts in search of environmental ‘triggers’ or causing factors for WCS were unsuccessful due to the unintentional sampling of mostly non-genetically susceptible or normal animals. Therefore, given the information provided and modern research techniques, nutritional studies will have the ability to make use of the genetically susceptible (WCS) animals to optimistically mimic WCS.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Lené van der Westhuizen on PienaarL@arc.agric.za

Lamb and Mutton Quality Audit

South African Retail Lamb and Mutton Quality Audit

Industry Sector: Cattle and Small Stock

Research focus area: Animal Products, Quality and Value-adding

Research Institute: Agricultural Research Council – Animal Production Institute

Researcher: Dr Michelle Hope-Jones

Title Initials Surname Highest Qualificaion
Dr PE Strydom Ph.D Animal Science
Dr L Frylinck Ph.D Biochemistry
Dr SM van Heerden Ph.D Home Economics
Prof A Hugo Ph.D Biochemistry
Ms J Anderson N D Analytical Chemistry
Mrs JD Snyman N D Food Technology

Year of completion : 2018

Aims of the project

  • To measure the instrumental/physical quality (shear force tenderness, water holding capacity/cooking loss, fat and muscle colour, collagen properties, oxidative status (rancidity)), sensory qualities and chemical composition of lamb and mutton rib or loin chops (M. longissimus dorsi) from various retail outlets (including brand names and generic products).
  • To determine the reasons for variation in quality by chemical, histological, physical and biochemical tests.
  • To use the information from 3.1 and 3.2 to arrive at a list of factors needed to be addressed in research and/or technology transfer to improve meat quality in South Africa.

Executive Summary

Twenty three products (lamb loin chops) were identified and collected from the shelves of five major retail outlets and twelve smaller butcheries on 14 different dates over a three month period (n=306, certain products where not always available due to drought conditions). Products varied in type, namely Karoo lamb (lamb valued for it unique flavour attributes due to grazing on herbaceous bushes and shrubs from a particular region of South Africa), free range or feedlot. Products also varied in packaging (Modified atmospheric packaging: MAP, PVC overwrap, to openly displayed on shelves) and retailers and butcheries were spread over various socio-economic areas. Price was recorded and shear force tenderness, sensory evaluation (tenderness and flavour), colour of meat, drip loss, cooking losses and meat/fat/bone ratios were measured as properties valued by consumers at or after purchase. Physical, histological and biochemical measurements (proximate and fatty acid analyses, lipid oxidation and collagen) were performed in an attempt to explain variations in consumer related properties.

  • Both instrumental and sensory evaluations showed tenderness to be at a high level of acceptance across the board. The Karoo samples were the most tender with the free-range samples performing the worst especially with regard to sensory tenderness.
  • Karoo lamb stood out for ‘barnyard’ aroma and flavour while free-range samples stood out for ‘Karoo bossie” aroma and flavours meaning they could be distinguished from the other samples and from each other. In both cases however, the scores were of a low intensity. Karoo and free-range lamb are purchased for their distinctive flavour.
  • Karoo and free-range samples lost less drip during cooking compared to the remaining products. Thawing loss was very low in general for all the products.
  • Karoo and free-range products have more loin muscle and less fat per chop compared to feedlot products.
  • Colour of all products was at an acceptable level with no distinct pattern showing for any particular product.
  • Lipid oxidation was at a good level over all products and fatty acid profile were consistent with free-range vs. grain-fed products. This makes the lack of free-range and Karoo flavours more perplexing.
  • Karoo and free-range products were more expensive. Regarding the remaining products, price correlated more with socio-economic area and butchery vs. retailer.
  • In general lamb is of a good quality except for drip loss which needs to be attended to. This could be due to incorrect abattoir practices. Karoo lamb is sold at a premium and its lack of flavours is of concern. The consumer however is able to consistently buy tender loin chops at any retailer or butchery.

Popular Article

Quality audit of South African lamb

Dr Michelle Hope-Jones, Researcher: Animal Production Institute, Food Science and Technology Department

Meat tenderness and other quality traits are influenced by a combination of pre-harvest, slaughter and post-harvest conditions and interventions. Research addresses these factors in order to ensure maximum satisfaction for the consumer.

However, the success rate of various sectors of the meat industry to use these technologies may vary depending on factors like technical skills, knowledge, market sector, financial viability and others.

While new projects are designed to address quality challenges, very little is known about the quality of red meat offered to the consumer at various outlets. To this end, a lamb audit was recently conducted to determine the variation in quality (tenderness, colour, water properties and others) within and between different types of outlets, and also to attempt to verify the reasons for variation in quality, so that research or technology transfer can address specific problems.

Product auditing process

The fact that meat in general is distributed all over the country from various production and processing plants, and considering that much of those operations are in Gauteng and distribute to Pretoria outlets, the study was limited to proper sampling and testing within the Pretoria metropolis. All the selected outlets receive meat from different operations, assuring a reliable sample of the industry.

Twenty three products (lamb loin chops) were identified and collected (when available) from the shelves of five major retail outlets (R) and twelve smaller butcheries (B) on 14 different dates over three months (n = 306). Products varied in type, namely Karoo lamb (valued for its unique flavour attributed to grazing on herbaceous bushes and shrubs from a particular region of South Africa), as well as free range and feedlot lamb.

Products also varied in packaging, from modified atmospheric packaging (MAP), where high levels of oxygen are pumped into packages in order for the meat to maintain the desirable red colour that consumers prefer, to PVC overwrap, and also open products displayed on shelves.

Retailers and butcheries were spread over various socio-economic areas.

Evaluation of palatability

The palatability of meat is determined by a combination of tenderness, juiciness and meat flavour.

Tenderness and juiciness

Tenderness is the most variable quality characteristic and is also rated by consumers as the most important sensory attribute. Figure 1 shows that purchasing from retailers vs. butcheries had little effect on tenderness, with instrumental test levels (Warner Braztzler Shear Force, WBSF) being at an acceptable level across all outlets. All of the Karoo products however were more tender. This could be attributed to the use of growth promotants in feedlots.

There was a strong correlation between sensory tenderness (rated by a trained panel) and WBSF. Two of the Karoo products, R2K and B6K, stood out as being more tender.

One of the free range products, R5FR, performed poorly on tenderness, but also scored lower for juiciness. This could probably be attributed to abattoir processes. Increased juiciness can give the perception of a more tender product and the relationship between the two attributes can clearly be seen in the figure. Most of the products which scored low for sensory tenderness (tougher), scored low for juiciness too.

Hoewever, the overall good level of tenderness is good news for the industry.

Flavour and aroma

In the case of lamb, flavour and aroma can play as an important role as tenderness. This is especially the case when comparing free range lamb to feedlot lamb (grass-fed vs. grain-fed) and even more so with Karoo lamb, which has a very specific flavour and aroma. As expected, the three Karoo samples scored higher (a more intense aroma) for ‘barnyard’ aroma, although interestingly not for ‘Karoobossie’ aroma, except for one Karoo product. The opposite was found for the two free range products, which had higher ‘Karoobossie’ aroma when compared to the Karoo products, but did not have a strong ‘barnyard’ aroma.

When looking at the flavour profiles, once again the three Karoo samples stood out as having a stronger ‘barnyard’ flavour. The Karoo samples did not really stand out as having a ‘Karoobossie’ flavour. As Karoo lamb is sold at a premium for its very distinct flavour, it would therefore be expected for this flavour to come out strongly. Instead, the taste panel identified the Karoo samples more as grass-fed meat.

Drip loss

All the free range products, as well as two of the Karoo products (R2K and B6K), had much less drip loss (the liquid you would find in the tray) compared to the other products. In fact, they had just over half the drip loss compared to the product with the most drip (R4).

Colour

All products across the board fell into the distinctly brown category. It was expected that packaging, or whether a sample was cut fresh or was on display, would make a difference to the colour of the meat, but not even the MAP packaged samples were of a desirable colour. This is of concern as consumers rely on visual appearance at the point of purchase and meat with a bright cherry red colour is associated with freshness.

Fat and meat (muscle) ratio, price

Figure 2 shows the average percentage of fat and the actual muscle for loin chops from the various outlets. All the Karoo (K) and free range (FR) products had more meat (a greater percentage of loin muscle), compared to the other products. It was however slightly unexpected, as feedlot meat production employs beta-adrenergic agonists, which should increase muscle yield and decrease fat percentage.

However, the feedlot lamb still had a higher percentage of fat compared to Karoo and free range samples, which could overshadow the increase in muscle yield of feedlot samples. Fat percentage followed a pattern of decreasing with an increase in loin muscle, with the Karoo and free range samples having less fat.

Price

There was a strong correlation between price and loin muscle, with a larger percentage of loin muscle resulting in an increase in price.

The Karoo and free range products were markedly more expensive, except for R2K (which was sold at a lower level retail store which was more accessible to the bulk of the public). All other Karoo products were sold at butcheries in areas of increased socio-economic status. The area in which the products were bought and the type of retailer/butchery that it was bought from, seem to be more of an indicator of price, than the percentage loin muscle, with stores in higher income areas charging more.

Problems to be addressed

With lamb being an expensive product, it is good to see that the consumer can consistently buy a tender product. There are, however, a few problems which were identified.

  • Karoo lamb, which is sold as a speciality product, does not consistently stand out from other free range products.
  • Colour as a whole is also a problem, with lamb meat not having the cherry red colour that the consumer associates with freshness.
  • Generally only 50% of a loin chop consists of meat and price alone does not seem to be a very accurate indicator of how much meat the consumer will get, except for the more specialised Karoo and free range products, which have a much better meat to fat ratio.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Michelle Hope-Jones on hopejonesm@arc.agric.za

Blackfly outbreak predictive model

Development of a predictive management model for Orange River blackfly outbreaks

Industry Sector: Cattle And Small Stock

Research Focus Area: Animal Products, Quality and Value-adding

Research Institute: University of KwaZulu-Natal

Researcher: Dr Nicholas Rivers-Moore PhD

Research Team:

Title Initials Surname Highest Qualification
Dr Helen Dallas PhD
Dr Robert Palmer PhD
Mr Shahin Naidoo BSc (Hons)
Ms Esther Ndou BSc (Hons)

Year of completion : 2017

Aims Of The Project

  • To determine the amino acid profile of South African beef
  • To determine the validity of using nitrogen and a specific Jones factor to define protein quantity
  • To determine the protein quality of South African beef in the context of human nutrition

Executive Summary

Blackfly outbreaks on the Orange River impact on the agricultural sector through loss in conception, stock mortalities and loss in body weight gain, with losses of over R333 million pa. The Blackfly Control Programme has been in place for some twenty years, using a combination of bacterial and organophosphate applications at river breeding sites. This should have resulted in as many years worth of monitoring data, which, in analysis with flow data, would have provided a useful long-term dataset. Given acknowledged challenges, this has not been the case to the degree hoped for, with periodic outbreaks of blackfly continuing to occur, and the monitoring dataset being patchy and seldom evaluated. New thinking is needed that builds on existing research to reduce the chances of repeated outbreaks.

The aims of this study were threefold: to test and refine an existing Bayesian network predictive model of blackfly outbreaks; to undertake climate change scenario analyses to assist with future planning; and to provide an evaluation framework for blackfly monitoring data.

Fourteen sites between Douglas and Blouputs were monitored over four surveys: November 2015; March 2016; July 2016 and December 2016.

Data collected were blackfly samples (by species, density and relative abundances), hydraulic data (current velocities associated with multiple sample points per site), and water quality data (spot measurements of pH, conductivity, turbidity). Hourly air temperature data has been collected for 13 sites using Hobo TidBit data loggers, for 4 November 2015-5 December 2016. Water quality was fairly consistent between sites, but showed seasonal variation. Conductivity and pH had little impact on blackfly species patterns, with the exception of very high (> 1000μS.cm-1) conductivities in the irrigation return flow channels. Diatom data do, however, suggest that conductivities in the main Orange River have been increasing. Turbidity was a key driver in triggering ecosystem switching between dominance of pest blackfly species, and other blackfly species co-occurring with benthic algae.

Data confirm that the Orange River system switches between two states, viz. a high turbidity state favouring pest blackfly, and a clearer state favouring algal growth and where blackfly numbers are lower. Flow volumes and water temperatures affect turbidity levels, efficacy of larvicides, and availability of habitat for various ecosystem components (benthic algae, blackfly species). Thresholds were successfully identified from the abiotic-biotic relationships, which were incorporated into a Bayesian network model to predict the probability of blackfly outbreaks.

A predictive management framework was successfully constructed. An evaluation framework where ongoing monitoring by the Department of Agriculture, Forestry and Fisheries, and stakeholder involvement has been integrated through the development of a mobile phone App with an associated website. These are available through the Google Play App store (search for “Muggies”) and at www.muggies.org respectively. These also include links to two YouTube videos explaining how to download the App and to upload data, with explanations of the scoring systems. All data uploaded makes use of Google Pins, so that the data are geo-referenced. Model predictions are available to users.

Additional comments

A follow up article in Landbouweekblad has been confirmed with Landbouweekblad staff. Both MSc studies are due to be submitted in the next 1-3 months respectively. Two scientific papers from this research are currently being prepared for submission and review.

Objectives:

  • To test and refine the recently developed pilot probabilistic blackfly outbreak model by inclusion of temperature and turbidity data, and using previous flows and monitoring data
  • To undertake climate change scenario analyses to assist future management planning
  • To provide an evaluation framework for monitoring data of blackfly larval densities, based on the outbreak model

POPULAR ARTICLE

Boere wen oorlog teen muggies

Dr. Nick Rivers-Moore.

Boere in die omgewing van die Middelen Benede-Oranjerivier kan nou danksy tegnologie en ’n nuwe model help om muggie-uitbrekings beter te bestuur.

Met die selfoontoepassing Muggies kan enigiemand inligting deurgee wanneer groot getalle muggies in die 1 200 km van die Oranjerivier tussen Hopetown en Sendelingsdrif voorkom.

Die inligting sal saam met ander gereelde waarnemings deur die staat in ’n nuwe voorspellende bestuursmodel gebruik word om groot uitbrekings van muggies beter te kan bekamp. Die model, die toepassing en die webwerf www.muggies.org is in ’n navorsingsprojek ontwikkel wat in Julie vanjaar voltooi is. Die navorsing, onder leiding van dr. Nick Rivers-Moore, is deur die Waternavorsingskommissie (WNK) en die nasionale organisasie vir rooivleisnavorsing en -ontwikkeling (RMRDSA) gefinansier.

MUGGIESKADE

Die skade wat veeboere, spesifiek skaapboere, in dié gebiede aan die Oranjerivier ly, is sowat tien jaar gelede op minstens R300 miljoen per jaar geraam. Mnr. Hoffie Joubert, lid van Agri SA se nasionale waterkomitee belas met die uggieprobleem, sê dit is nou waarskynlik baie meer.

Luidens die jongste navorsingsverslag, Development of a Predictive Management Tool for Orange River Blackfly Outbreaks, kom verskeie muggiespesies in die gebied voor, maar dit is veral Simulium chutteri wat boere laat skade ly. Die ander spesies wat probleme veroorsaak, is S.damnosum, S. nigritarse en S. adersi. Volwasse wyfies van S. chutteri en S. damnosum voed op soogdiere se bloed, en laasgenoemde twee s’n op voëls.

Nick sê mannetjies vreet nek- tar en stuifmeel. Wyfies vreet ook hoofsaaklik nektar, maar het soos muskiete proteïen uit bloed nodig vir hul eiers om te ontwikkel. Dit is egter nie net skape en dus boere wat geraak word nie. Uitbrekings van muggies raak ook die toerismebedryf en inwoners van die omgewing. Die ergernisvlakke raak in ’n uitbreking van muggies so hoog dat werkers nie kan werk nie en toeriste sulke gebiede vermy. Luidens die verslag word die bestuur van die probleem bemoeilik omdat daar verskeie groepe met verskillende belange is, wat teen mekaar opgeweeg moet word. Ideale omstandighede vir groot uitbrekings hou onder meer verband met die volume water wat in die rivier vloei. Muggies hou van troebel water wat vinnig vloei. “Wanneer water stadiger vloei, is dit helderder. Water wat vinniger vloei, is troebeler. S. chutteri voed op sy doeltreffendste met watervloei van meer as 100 m per sekonde of ’n spoed van meer as 1 m/sekonde,” sê Nick.

Die vloei van die Oranjerivier het deur die jare aansienlik verander vanweë verskillende waterskemas, soos die Vanderkloofdam sedert 1977, die Gifkloofdam sedert 1971 en dan ook meer onlangs die Lesotho-Hooglandwaterprojek.
Veeboere verkies dalk ’n laer watervloei om uitbrekings van muggies te voorkom, maar besproeiingsboere met wingerd het meer water nodig, en Eskom het ’n bepaalde watervloei nodig om hidro-elektrisiteit op te wek.

Luidens die verslag moet ’n mens onthou dat hoewel muggies as ’n plaag beskou kan word, is dit ook ’n belangrike bron van voedsel vir baie roofdiere in die water is. “Die bestuursdoelwit behoort eerder die beheer as die uitwissing van muggies te wees.”

BEHEERPROGRAM

Die uitbrekings van muggies kom van tyd tot tyd voor. Die jongste een was in 2011 en voor dit in 2000-’01. Die staat het in die vroeë 1990’s met bestrydingsprogramme begin. Dit behels die toediening van ’n larwedoder vanuit ’n helikopter. Dit word gewoonlik drie keer in die herfs en ses keer in die lente toegedien. Twee middels is in Suid-Afrika vir die bestryding van muggies geregistreer: Vectobac® (reg.no. L7224, Wet 36/1947) en Abate® (reg.no. L2413). Opvolgnavorsing is onder meer tien jaar later gedoen om te kyk na alternatiewe larwedoders weens weerstandigheid by larwes teen temefos, ’n bestanddeel van Abate®.

Ondanks die bestrydingsprogram het uitbrekings steeds voorgekom, wat mense skepties laat raak het. Luidens die verslag hang die sukses van die program baie af van die korrekte tydsberekening van die toediening. Die redes vir die herhaalde en voortdurende uitbrekings is ingewikkeld. Dit sluit in hoër as normale watervloei in die winter, veranderinge in troebelheid, afwisseling van die oorheersende muggiespesie, larwedoderweerstandigheid en bestuurskwessies.

NUWE NAVORSING

Verskeie pogings is al aangewend om die voorkoms van uitbrekings te verminder, waaronder ’n geïntegreerde bestrydingsprogram en voortgesette monitering, ’n waarskynliksheidsmodel om te kan voorspel wanneer volwasse wyfies ’n groot ergernis kan wees, optimalisering van larwedodertoedienings en die skep van ’n advieskomitee. Nie een het die gewenste gevolge gehad nie. As deel van navorsing in 2014 is onder meer vasgestel dat die mees onlangse uitbrekings waarskynlik eerder aan bestuurskwessies as biologiese kwessies toegeskryf kan word. Verder taan belanghebbendes se belangstelling gewoonlik wanneer die probleem nie groot is nie, en verhoog eers weer wanneer daar ’n uitbreking is.
“Die probleem is tipies van die meeste plaagbestrydingsprogramme, en wys op die behoefte aan langtermyntoesig,” lui die verslag.

Die doelwitte van die jongste navorsing het ingesluit om ’n voorspellende model te ontwikkel, vir die eerste keer data oor troebelheid en watertemperatuur in te sluit, en ook te kyk na die moontlike invloed van klimaatsverandering. Alle vorige navorsingsinligting is wéér ontleed, maar dié keer saam met nuwe inligting wat in 2015 en 2016 ingesamel is. Dit het onder meer weeklikse troebelheidsen uurlikse watertemperatuurinligting ingesluit. Seisoenale insamelings van larwes en papies is ook in verskillende hidrolitiese biotope en habitatte gedoen om seisoenale veranderinge in die betreklik hoë voorkoms van verskillende muggiespesies te kan verstaan. Om die moontlike invloed van klimaatsverandering te kan bepaal, is inligting van die Universiteit van KwaZulu-Natal se departement hidrologie gebruik, wat aandui watervloei kan in die nabye toekoms 60% hoër wees.

BEVINDINGS

Die belangrikste bevindings van die jongste navorsing is: Die gehalte van water by die verskillende terreine was redelik dieselfde, maar het volgens seisoene gewissel. Die geleidingsvermoë van water en die pH-vlakke het ’n klein invloed op die patrone van muggiespesies gehad. Troebelheid was ’n sleutelrede vir ’n ander muggiespesie om die oorheersende een te word. Die water se vloeivolume en temperatuur het ’n invloed op troebelheidsvlakke, die doeltreffendheid van larwedoders en die beskikbaarheid van habitat vir verskeie ekostelsel-onderdele. Drempels is in die muggies se abiotiese-biotiese-verhoudings geïdentifiseer en in die model ingesluit waarmee die waarskynlikheid van uitbrekings van muggies voorspel kan word.

TOEKOMS

Vir die voorspellende bestuursraamwerk om suksesvol te wees, moet die insameling van inligting oor konsentrasies van muggies voortgaan. Inligting moet ook ingesamel word oor troebelheid en die voorkoms of afwesigheid van bentiese alge, wat verband hou met troebelheid. Al hierdie inligting moet, tesame met die lastigheidsindeks, op die webwerf gelaai word.
Die voorspellingsmodel moet dan met die inligting bygewerk en die verskillende data-onderdele moet van tyd tot tyd geoudit word. Wat egter ook baie belangrik is, is dat ’n “kampvegter” na vore moet tree, wat die raamwerk sal administreer en die maandelikse tariewe sal betaal vir die webwerf en die selfoontoepassing.

Die navorsers stel ook voor dat die ekonomiese invloed van muggies in die streek hersien word. Hoffie is opgewonde oor die bevindinge in die jongste navorsing en verwelkom die voorstel dat weer na die ekonomiese invloed gekyk word. “Inligting oor die omvang van die ekonomiese skade is belangrik vir die regverdiging van die toediening van larwedoder.” Hy sê die invloed van die gehalte van water op die toediening van middels moet ook nagevors word. Tans steun die plaagbestrydingsprogram net op die gebruik van Vectobac®, ’n organiese middel, weens die weerstand wat teen Abate®
ontwikkel het. Abate® het egter ’n baie groter reikafstand.

Hoffie sê die voorgeskrewe tydperk wat Abate® nie gebruik kon word nie, is nou verstreke en dit is belangrik dat dit weer getoets word. Agri Noord-Kaap gaan boere aan die rivier uitwys om die toepassing te gebruik om inligting oor muggies deur te gee en die organisasie sal dit monitor.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project –
Nicholas Rivers-Moore on blackfly1@vodamailcom

The food composition of raw and cooked beef offal

The food composition of raw and cooked beef offal (A Pilot study, as a pro-active activity)

Industry Sector: Cattle and Small Stock

Research focus area: Red Meat Safety, Nutritional Quality and Value

Research Institute: ARC-Animal Production Institute

Researcher: Dr SM van Heerden

Research Team:

Title Initials Surname Highest Qualification
Dr LE Smit
Mrs MM Magoro
Dr IB Zondagh PhD
Mrs JM Van Niekerk
Mrs JM Masilela
Mrs C Rapelego

Final report approved: 2017

Aims of the project

  • To determine selected nutrients in a pilot study of raw and cooked, red and white South African beef offal
  • To determine the total profile of nutrients should the results from the pilot study indicate the need for this?
  • To make the data on the nutrient composition of South African beef offal available to the MRC to be included
  • Into the South African Food Composition Tables of the Medical Research Council (MRC)
  • To compile and publish a comprehensive booklet on the nutrient content of South African beef offal

Executive Summary

Scientific literature on the nutrient content and food composition tables of offal is relatively scarce. However the nutritive value of all food products including meat and meat products is important, in view of the consumer interest and demand for a healthier lifestyle (Pearson & Tauber, 1984). Therefore, there is a great need for more detailed information on food with adequate nutritive value, especially protein, for the informal and poorer sections of the population in South Africa.

With the WHO’s estimation that 5 million people are dying every year from starvation, more attention should be given to the possibility of using proteins such as offal (beef, sheep), as protein sources in the diet (Poonam & Lawrie, 1986:144).

Offal, or organ meats, refers to the internal organs and entrails of a butchered animal, makes up a substantial portion of an animal’s meat weight. The word does not refer to a particular list of edible organs, but includes most internal organs other than muscle and bone. http://en.wikipedia.org/wiki/Offal). It is also described as those parts of a meat from a carcass which are used as food but which are not skeletal muscle. It covers insides including the heart, liver, and lungs (collectively known as the pluck), all abdominal organs and extremities: tails, feet, and head including brains and tongue. In the USA the expressions “organ meats” or “variety meats” are used instead (http://www.offalgood.com/what-is-offal).

In South Africa offal is mostly enjoyed by South Africans of diverse backgrounds. Due to the popularity of this dish, it is one of the few customs that white (especially Afrikaners) and black South Africans share. Offal dishes in South Africa include stomach, hooves, shin, intestines, liver, head, tongue and very rarely in certain communities, testicles, and are consumed ‘fresh’ (i.e. not frozen).

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Ina van Heerden on Ina@arc.agric.za

Brine injection of beef

The effect of moisture enhancement by brine injection on the chemical, microbial and sensory quality of beef

Industry Sector: Cattle and Small Stock

Research Focus Area: Animal Products, Quality and Value-adding

Research Institute: Agriculture Research Institute – Animal Production Institute

Researcher: Dr Phillip Strydom PhD Animal Science

Title Name Surname Highest Qualification
Prof CJ Hugo PhD
Dr C Bothma PhD
Dr C Charimba PhD
Mr M Cluff M.Sc Agric
Ms E Roodt M.Sc Agric
Mr Z Kuhn B.Sc Agric Hons
Mr H Steyn B.Sc Agric Hons
Ms E Moholisa M.Sc Agric
Dr M Hope-Jones PhD
Ms JM Boikhutso MInst. Agrar: Food Production and processing
Ms MM Magoro M.Tech.Food Technology
Mr CA Seomane Grade 8, Meat Technology Research Assistant, 27 years’ experience
Mr WK Seanego Grade 7,Meat Technology Research Assistant 11 years’ experience
Dr SM Van Heerden PhD
Ms OC Sehoole BSc Food management (4 years)
Ms TM Mokhele BInstAgrar Food Processing (4 years)
Ms JH Masilela Grade 9, sensory research assistant 26 years experience

Aims Of The Project

  • To determine the effect of injection of non-nitrite moisture enhancing injection brines on the nutritional value of beef.
  • To determine the effect of injection of non-nitrite moisture enhancing injection brines on the chemical and microbial stability of beef under refrigerated and frozen storage.
  • To determine the effect of injection of non-nitrite moisture enhancing injection brines on the textural and sensory properties of beef.

Year of completion : 2017

Executive Summary

The effect of different injection levels of non-nitrite brines on meat quality characteristics of unaged and aged beef loins was investigated. Beef loin cuts aged for 3 or 10 days were injected with 5, 10, 15 or 20 % brine (weight basis) and compared with non-injected loins with regards to nutritional value, sensory and textural quality, water holding properties, and colour, chemical and microbial stability.

The results illustrated that brine injected in beef loin are retained between 50 to 70 % of injection levels. This resulted in a clear nutrient dilution, best illustrated by the decrease in protein content from 21.1 % in the Control loins to 18.5 % in the loins injected to a target yield of 20 %. The dilution of protein became evident only at an injection level of 10 % and higher but did not increase further with higher levels of injection. Brine injection also increased the levels of phosphate (35 %) and salt (50 %) and the effect was consistent across all injection levels. This is very important since salt and sodium content of especially meat products are currently under the spotlight with new legislation on sodium levels of meat products being implemented on 30 June 2016.

The chemical stability of beef loin as measured by TBARS (measurement of rancidity) was not affected by brine injection. Neither fresh samples, displayed for 6 days, or frozen samples, stored for 180 days, were affected, despite the fact that salt is a pro-oxidant and chemical deterioration was expected with brine injection.

Colour and colour stability were affected by brine injection. Initial colour (just after treatment) measured as chroma (typical colour of fresh meat) was negatively affected only at injection levels above 10%. However, as days on display continued (up to 6 days), all injected samples showed poorer colour stability (lower chroma values) than Control samples. Likewise, injected samples were duller (lower values for lightness, L*).

Brine injected samples tended to show higher initial (day of injection) total aerobic micro-organism counts (0.5 – 0.7 of a log) likely due to the recirculation of the brine during application. However, microbial growth was later (day 6 on the shelf) inhibited, probably by the potassium lactate in the brine mix, eventually leading to the brine injected samples having lower total aerobic bacteria loads (between 0.5 and 0.8 of a log) than Control samples. Also because of recirculation of brine, yeasts and molds were higher in injected samples (0.8 to 1.0 log) after injection, but differences between Controls and injected samples became insignificant after 6 days on the shelf.

Both Warner Bratzler shear force and sensory tenderness showed beneficial effects due to brine injection even at levels as low as 5 %. A slight linear increase (lower shear force and higher tenderness score) was observed with increasing level of injection although the effect was not statistically significant above 10 % injection level. The taste panel also scored injected samples higher for juiciness and although these scores increased slightly with level of injection, no significant effect was observed above 10% levels. As expected, the taste panel also scored injected samples higher for saltiness, but no off-flavours were identified.

Another advantage of brine injection was a reduction in thawing and total cooking losses. The maximum effect was observed at 5 % injection level and cooking loss slightly increased as injection level increased.

In conclusion, it seems that the advantages and disadvantages of brine injection is correctly balanced by the 10% brine injection limit enforced by the Agricultural Product Standards Act, 1990 (ACT No. 119 of 1990; 30 January 2015) for beef. Brine injection levels above 10% showed no additional effect on eating quality. Likewise, the negative effect on colour of freshly displayed meat deteriorated at levels above 10%, while the protein dilution effect also became evident at 10% level. Higher salt irrespective of injection level may be a health concern.

Popular Article

THE EFFECTS OF BRINE INJECTION LEVEL AND POST MORTEM AGING ON
SENSORY AND PHYSICAL CHARACTERISTICS OF BEEF LOIN
Phillip E. Strydom1,2*, Zarlus Kuhn3, Celia J. Hugo3 and Arno Hugo3

  1. Animal Production Institute, Agricultural Research Council of South Africa, Irene, 0062, South Africa
  2. Department of Animal Sciences, Stellenbosch University, Stellenbosch, 7602, South Africa.
  3. Department of Microbial, Biochemical and Food Biotechnology, University of Free-State, Bloemfontein, South Africa.
    *Corresponding author email: pstrydom@arc.agric.za

Abstract – The enhancement of beef, pork and chicken with brine solutions has become common practice in many countries.
The combined effects of aging and brine injection level on beef quality is unknown. Our study investigated the effects of five
brine injection level (0, 5, 10, 15 20%) combined with post mortem aging period (3 and 10 days) on sensory characteristics of broiled beef loin. Injected samples were scored higher for saltiness but aging reduced the effect. Brine injection had no effect on flavour but tenderness was improved up to 15% injection level. Apart from 0 and 5 % injection levels, aging had no effect on tenderness score. Juiciness was improved up to 10% injection level after 10 days aging and up to 5 % injection level for 3-day aged cuts. The results suggest that a maximum of 15% brine injection will give the best sensory results and save on post mortem aging time.

Key Words – tenderness, juiciness, saltiness.

I. INTRODUCTION
Brine injections have been used in the poultry industry since the 1950’s [1]. Red meat processors saw this technology
as an opportunity to improve beef and pork palatability that deteriorated as a result of the production of increasingly
leaner animals that contain less fat [2,3,4], although atypical flavours may also develop [2, 3]. Hamling et al. [5] found
that post mortem aging could be substituted by brine injection. High levels of injection may not necessarily improve
eating quality while other negative effects such as purge may also occur [6]. The abuse of brine injection of poultry meat
in the South Africa resulted in legislation stipulating a maximum of 10% to 15% brine for whole carcasses and portions,
respectively after extensive research. However, brine injection of beef in South Africa was limited to 10% without any
scientific verification [7]. Our study investigated the effects of post mortem aging and brine injection levels on sensory
quality of loin cuts of young grain-fed beef.

I. MATERIALS AND METHODS
Sixty beef loin primal cuts were subjected to five brine treatments: a non-injected control and four groups respectively injected to 5, 10, 15, and 20% level with a salt, sodium tripolyphosphate (STPP), potassium lactate containing brine; and two aging periods: 3 and 10 days post mortem. Loin steaks were oven-broiled and evaluated by a ten-member trained sensory panel on an 8-point hedonic scale for aroma, juiciness, tenderness/texture, beef flavour intensity,
metallic/tin-like/bloody, chemical (salty), and sour off-flavours. Data were subjected to analysis of variance for a splitplot
design with injection level as whole plots and days post mortem as sub-plots.

II. RESULTS AND DISCUSSION
Despite adding salt to the control samples, injected steaks scored higher values for saltiness, although level of injection
did not have an effect (Table 1). The effect of injection was less for cuts aged 10 days than for those aged 3 days. Knock
et al. [4] reported higher scores for typical beef flavours, when beef loins were enhanced with KCl brine to 8.5% level,
especially after 9 days aging. Although the different brine levels in our study had similar levels of salt, Knock et al. [4]
showed higher scores for saltiness and rancidity when salt levels were increased. In contrast to our study, Grobbel et al
[3] reported off-flavours, such as salty, metallic or chemical descriptors for brine injected beef loin. Injected steaks
scored higher for tenderness in our study irrespective of aging period. Higher injection levels generally gave better
results, although the effect plateaued at 15% injection level for 3 day aged steaks and at 10% injection level for steaks
aged for 10 days. Injected steaks also scored higher for juiciness. The effect of injection level on juiciness plateaued at
10% for steaks aged for 3 and at 5% for steaks aged for 10 days. Knock et al. [4] found no effect of brine injection will follow later (8.5%) on beef loin tenderness or juiciness, while Hoffman et al. [2] reported similar results as our study for four unaged muscle types injected to a 15% level. Hamling et al. [5] reported higher scores for tenderness, flavor and juiciness at 20% injection levels and this was unaffected by aging to 14 days. In our study, added effects of aging on tenderness and
flavour were found at 5 % injection level. Aging had no effect on juiciness perception, but 10 day aged samples injected
to 10 and 15% levels scored lower than 3 day aged samples. Likewise, all 10 day aged injected samples, except 20%,
scored lower for saltiness than 3 day aged samples.

I. CONCLUSION
Ten percent seems to be the optimum injection level for improved juiciness and tenderness of loin primals, while flavour
is not affected by brine injection. Perception of saltiness due to brine injection is reduced when samples are aged. In
general, brine injection can save on post mortem aging time with regards to improvement of tenderness.

ACKNOWLEDGEMENTS
PE Strydom thanks Dr Ina van Heerden and her sensory team for sample testing.

REFERENCES
1. Buchanan, B. F. (1955). Process for Treating Poultry. United States Patent Office. Patent 2 709 658, application 17
April 1951. https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/ pdfs/US2709658.pdf.
2. Hoffman, L. C., Vermaak, A., & Muller, N. (2012). Physical and chemical properties of selected beef muscles
infused with a phosphate and lactate blend. South African Journal of Animal Science 42: 317–340.
3. Grobbel, J. P., Dikeman, M. E., Hunt, M. C., & Milliken, G. A. (2008). Effects of different packaging atmospheres
and injection-enhancement on beef tenderness, sensory attributes, desmin degradation, and display color. Journal of
Animal Science 86: 2697–2710.
4. Knock, R. C., Seyfert, M., Hunt, M. C., Dikeman, M. E., Mancini, R. A, Unruh, J. A., & Monderen, R. A. (2006).
Effects of potassium lactate, sodium chloride, and sodium acetate on surface shininess/gloss and sensory properties
of injection-enhanced beef strip-loin steaks. Meat Science 74: 319–326.
5. Hamling, A. E., Jenschke, B. E., & Calkins, C. R. (2008). Effects of aging on beef chuck and loin muscles enhanced
with ammonium hydroxide and salt. Journal of Animal Science 86: 1200–1204.
6. Miller, R. 1998. Functionality of non-meat ingredients used in enhanced pork. Pork Quality Facts. National Pork
Board, Des Moines, IA, pp. 1–12. http://articles.extension.org/pages/27340/functionality-of-non-meat-ingredientsused-
in-enhanced-pork#Total_level_of_added_ingredients_and_injection_level.
7. Government notice No. 55 of 30 January 2015. Regulations regarding the classification and marketing of meat.
Department of Agriculture, Forestry and Fisheries, Republic of South Africa. http://www.gov.za/sites/
www.gov.za/ files/38431_reg10358_gon55.pdf.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project –  Dr Philip Strydom on pstrydom@arc.agric.za

Heterosis effects on beef sensory and leather quality traits

Characterization of breed-specific additive and heterosis effects on beef sensory and leather quality traits

Industry Sector: Cattle and Small Stock

Research Focus Area: Research Animal Products, Quality and Value-adding

Research Institute: ARC-Animal Production Institute Northern Cape Department of Agriculture, Land Reform and Rural Development and University of the Free State

Researcher: Prof Michiel M Scholtz D.Sc. Agric

Title Initials Surname Qualification
Mrs A Theunissen MSc Agric
Dr M.D. MacNeil Ph.D
Dr P.J. De Bruyn Ph.D
Prof F.W.C. Neser Ph.D

Year of Completion : 2017

Aims Of The Project

  • To characterize the maternal and paternal heterosis effects on sensory beef traits
  • To characterize the maternal and paternal heterosis effect on leather traits

Executive Summary

The project had two objectives, namely to estimate direct and maternal breed effects and heterosis contributions for Afrikaner (A), Simmentaler (S), Brahman (B), Charolais (C) and Hereford (H) on sensory carcass traits and leather traits.

Sensory carcass traits

Five sensory traits (tenderness, juiciness, aroma and flavor and residual connective tissue) and two physical meat traits viz shear force (N/2.5cm2) and cooking loss (%) were investigated. Data (N=375) arising from 5 straightbred and 24 crossbred combinations were modeled by multiple regression of the phenotypes on expected breed roportions and heterozygosity.

Only direct effects seem important for shear force, tenderness, and residual connective tissue. However, for juiciness and cooking loss maternal effects also seem relevant. This may indicate that effects manifested during the pre-weaning period on components of meat quality were retained through the time of harvest or a predisposition for creating differences in the sensory properties of the meat were established. The indigenous Afrikaner had generally the most favourable sensory profile relative to the imported breeds. This was particularly true for shear force and tenderness.

Sanga cattle, like the Afrikaner, are early maturing breeds. There is clear evidence that the use of exotic germplasm on Sanga breeds can increase feedlot performance and meat yield of cattle reared under South African conditions. Different crossbred genotypes also provide opportunity for more rapid conformation to the changes in market requirements and may offer opportunity for more revenue. However, it appeared based on the sensory data summarized, that crossbreeding with exotic germplasm has little to offer in terms of consumer satisfaction relative to the use of Afrikaner.

Leather quality

It is important to note that hides are normally purchased by weight, but leather is sold by surface area. It is therefore common practice to mechanically stretch the hides during tanning and manufacture. The standard practice is to stretch leather to 20% extension. There is however concern that this stretching may affect important aspects of leather quality and strength.

Hide yield (%) and 8 leather characteristics (leather yield (dm2/kg), force 20% extension (Mpa), extension grain crack (%), extension break (%), force break (Mpa), slit tear force (N/mm), distension grain crack (%), and force grain crack (N/mm)) were evaluated. The results indicate breed direct effects and individual heterosis, but not maternal effects, may be important for most of these traits. For all of the exotic breeds, direct effects reduced hide yield and increased leather yield relative to the indigenous Afrikaner. For both of these traits, individual heterosis effects arose primarily from indicus x taurus crossing with the Hereford x Brahman effect being most pronounced. Leather from the exotic breeds appeared to be stronger, as evidenced by greater direct effects for force required to achieve 20% extension and break, than leather from the indigenous Afrikaner. Direct effects on the extension required to crack the grain attributable to Hereford and Simmentaler were less than for the indigenous Afrikaner, Brahman, and Charolais. These results indicate opportunities to improve leather yield and quality through crossbreeding relative to straight bred Afrikaner.

Popular Article

There are 2 scientific articles, please contact the researcher for more information on this.

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Michiel Scholtz on GScholtz@arc.agric.za.