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Genetics of Meat Quality Traits Southern Crossbreeding Programme

Mick Deland and Dr Wayne Pitchford

• Improving breed utilisation for targeting specific markets
• Estimating genetic parameters for developing breeding objectives

Same age, same feed, different genetics, different yield

A collaborative project initiated with SA Cattle Compensation Funds involving :

Summary

Millions of dollars are lost to the beef industry each year because producers use inappropriate breeding practices. The price of meat is largely determined by decisions made two to three years before the product is sold to the consumer. The aim of this project is to study genetic aspects of traits associated with beef production as they affect meat quality and marketability so that the whole industry can increase returns. It will evaluate a range of breeds and promote the use of terminal crossing with appropriate sires for meeting specific markets. The project now has wider implications with collaborative work both nationally and internationally. First calves were born in 1994 and the final steer calves were slaughtered in December 1998. Laboratory analyses of meat samples is now complete and results are being analysed and prepared for publication.

Background

Carcass weight and fat cover are currently the main determinants of price for beef, however, within most markets other traits (e.g. marbling and yield) have an enormous impact on price per kg. The failure to regularly supply beef of consistent quality to such markets has reduced Australia’s market share in recent years. The most cost effective means of improving meat quality is to use appropriate genotypes, as producers are able to minimise the time taken to reach a given market specification whilst maximising the number of animals reaching that specification. In short, the greater amount of available information re carcass and breed characteristics, allows producers to better target specific markets and increase the competitiveness of their beef operation.

The Southern Crossbreeding Project was established at Struan Research Centre with funding from the South Australian Cattle Compensation Fund. The project is linked with the Beef Industry Cooperative Research Centre (CRC) centred in Armidale, Quality Beef Genetics (Genetics Australia) based in Victoria and Davies Gene Mapping programs (University of Adelaide). Some common sires are used in the programs and include the following breeds: Angus, Belgian Blue, Hereford or Poll Hereford, Jersey, Limousin, South Devon and Wagyu. Some sires are also common to US, NZ, French and Belgian breed evaluation programs giving the project wide representation and an international context. Sires were mated to Hereford (Horn/Poll) cows each year for four years. Calves were weaned at approximately 250 days of age and then, grown out for another 100–250 days on pasture. Heifers were lot fed for 70–100 days and steers for 150–180 days. Associated studies include projects with Elders to improve returns from the Korean market and, Michell leather, to improve the export performance of hides.

The original project has become the core resource for an ever increasing number of interested parties and has now become an effective collaboration between private, industry, government and university interests.

Struan Research Centre

(Mick Deland, Rod Ross and Farm Staff)

The base herd was owned by SARDI. Traits were recorded on all animals by PISA/ SARDI staff and include gestation length, calving difficulty, calf deaths, and calf size at birth (e.g. weight, length, height and girth). Calves were then weighed and P8 fat depth measured (Michael Milne) every 50 days until slaughter. All data was initially entered on computer by Rod Ross who then provided either basic data or summaries to groups or individuals including participating breed societies and Breedplan.

At 300 and 500 days, loin-eye muscle area and marbling were measured using ultrasound (commercial operators) and the calves are visually assessed (by staff from Elders and NSW Agriculture) to develop more accurate value based trading systems for the beef industry. This data will be used to assign values to calves at any time in the future and also to predict carcass traits.

At Struan, biopsy samples of fat and muscle were taken from calves at about 10 months of age. The results of assays were then correlated with assay data from carcass samples. Carcasses were assessed for weight, fat depth at P8 and site of quartering, marbling, eye muscle area, meat and fat colour, meat and fat texture and butt shape. More than 100 measurements were taken on each carcass and samples of meat and fat were taken for chemical assays and meat yield, from one slaughter group.

Meat marketing relies heavily on visual impact and each carcass has been photographed at the quartered site to determine its visual appeal. In addition, 200 carcasses have been photographed for image analysis and yield estimation.

University of Adelaide (Wayne Pitchford, Cindy Bottema, Brian Siebert and research students)

University staff were involved in taking additional measurements on the animals. Skeletal dimensions were recorded on growing animals to enable the development of carcass components (bone, muscle and fat) to be modelled in addition to weight alone. Parameters include height, length and girth, hip and stifle width of growing animals and hot carcass length and pelvic area of carcasses.

David Rutley, a PhD student, was responsible for obtaining measurements and analysing the data. The initial analysis indicates that approximately 90% of the variation in final carcass weight can be accounted for by traits which can be measured or visually assessed prior to feedlot entry.

At 300 days and then again at slaughter, muscle and fat samples were taken and analysed for:

• intramuscular fat content, fat melting point and fatty acid composition, which are important for our Asian markets (Dr Brian Siebert, Enoch Aduli, PhD student and Naomi Grey, Honours student)
• b-carotene concentration, which is responsible for yellowness of fat, an important issue due to price penalties which cost the Australian industry about $18 m per year (Zbyszek Kruk, PhD student)
• vitamin E concentration, important for shelf life (Roger Lawes, Honours student)
• growth hormone receptor messenger RNA levels in muscle of different breeds (Jason Ekert, Honours student).

SARDI genetics group (Raul Ponzoni and Andrew Ewers)

Dr Raul Ponzoni, a geneticist, was involved in the design of the project and is also a co-superviser of David Rutley's PhD project. He is not involved in data collection but provides invaluable support for data analysis work.

Preliminary results of this work are now available. Meat yield (%) was estimated from eye muscle area and fat depth using equations available from MRC and Ausmeat. When checked against the actual yields, based on dissection, it is clear adjustments need to be made to the original formulae. As a result of this, some of the breed rankings differed from that expected by industry. Breed societies represented in the project provided funds, to determine actual yields of meat, fat and bone from each steer carcass processed in 1997. Boning facilities at Metro Meat International were used to undertake this trial.

Our bone out trial, provided information on over 100 weights of meat, fat and trim from 241 steers from 10 breed combinations (7 from Crossbreeding Project and 3 from the Gene Mapping Project).

SARDI Biochemistry group

The Honours student Roger Lawes investigated Vitamin E, Selenium and Haemoglobin differences between breeds, and between sires within breeds. Some breed and sire differences were found to be significant. Vitamin E is of particular importance because it affects the shelf life of beef. There appears to be potential to make genetic improvements in this trait by selection. This is the first time breed and sire differences have been demonstrated in these traits in cattle.

AW & PR Davis Pty Ltd (Tony Davis)

The cattle were sold at 500 days to a commercial cattle company (AW & PR Davis Pty Ltd) with an agreement that the cattle would remain together and measurements would be taken up to and after slaughter. This represented a very large commercial commitment ($250k) to the research program. This grant enabled the research centre to obtain operating funds from sale of calves and the feedlot phase of the trial to be conducted to achieve export market weights.

NSW Agriculture (Bill McKiernan)

Bill McKiernan has been working with the Meat Research Corporation in developing Value Based Trading Systems for live cattle. The visual assessment of the muscle on an animal is an important part of this. Bill became interested in our project because it included a large number of contemporary cattle from a broad range of genotypes. He regularly travelled to Struan, Martindale, and various feedlots, to score our animals during their development. Results indicate that much of the variation in carcass weight and quality can be predicted before the steers enter the feedlot.

Elders Limited (Dennis Wignall, Greg Black and Nick Crichton)

Most agents grade or score cattle in commercial practice for their clients. Elders first became involved in the project by providing commercially recognised muscle scoring at the same time as Bill McKiernan. These scores will be correlated with carcass data.

While developing strategic alliances in Korea, Elders has found that the primary resistance to Australian beef in Korea is that it tastes and feels different from premium local beef. With improved use of genetic resources and nutritional management, it may be possible to develop production systems in Australia for supplying high quality beef to Korea.

In response to this, a project, which was an extension of the Gene Mapping and Crossbreeding Projects was devised. Funded equally by Elders and the Australian Research Council, this project aimed to compare premium beef from the Korean cattle breed Hahnwoo with a broad range of Australian genotypes for a host of meat quality traits. The extension consisted of:

• analysis of meat and fat samples from Korea
• additional meat quality measurements
• taste evaluation by a trained panel
• continuation of fatty acid analyses.

Nick Crichton of Elders travelled to Korea to observe handling and marketing. Mick Deland and Wayne Pitchford travelled to Korea to develop this further.

Elders obtained meat (from 100 primals), trim (fat) and feed (dietary) samples from large Korean feedlots currently supplying premium quality beef to local markets. In addition to obtaining representative samples, Elders assessed the carcasses, which included measurement and assessment of hot carcass weight and length, dentition, bruising, meat and fat colour, eye muscle area, marbling, subcutaneous fat depth at P8 and site of quartering, and visual meat texture.

The Korean meat and fat samples were analysed in parallel with those from our research programs. Fat content, fatty acid composition of triglycerides and phospholipids measuring C14–C22 and b-carotene concentration in meat and fat samples were determined. Feed samples were analysed for fatty acid composition, energy, protein and specific amino acid levels. Additional meat quality measurements performed on the samples from the research herds and Korean samples included pH, juiciness, cooked meat colour, tenderness and taste as scored by a trained testing panel. The data will allow genes to be mapped and genetic parameters estimated for each of these traits.

Results to date indicate that Australian cattle breeds differ in fatty acid composition. As fatty acids have distinct melting points, the fatty acid composition can alter fat hardness which then affects meat processing. Moreover, the fatty acid composition may be important in determining the taste and texture of the beef.

A PhD student (Elke Stephens) was funded by the project.

Beef Industry Cooperative Research Centre (CRC)

One of the real limitations with published Estimated Breeding Values (EBVs) in Australia is that they are done within breeds. As a consequence of this, it is currently impossible to directly compare a sire in one breed with one in another. This project and the crossbred EBV project, will supply basic data to the Animal Genetics and Breeding Unit to allow, for the first time, across breed and crossbred EBVs. 

Applied Design and Developments (Neil Wilson)

Our first slaughter (1994 drop heifers) was conducted when . Applied Design and Developments were developing a video image analysis (VIA) system for chiller assessment of meat and fat colour, marbling and eye muscle area. They were keen to assess our carcasses because of the broad range of biological types and the benefit to us was that we now have digitised images of most carcasses from this slaughter stored on disk for future reference.

Northfield Laboratories Pty Ltd (Peter White and Alex Todd)

Northfield Laboratories developed a vaccine for Rotovirus, a virus which often leads to extended hospitalisation when contracted by children. As part of the development, all of our 1996 drop calves and some of our 1994 drop calves were injected with Rotovirus and tested for antibody response. The antibody response data will be analysed to examine breed and sire differences in immune function.

Metro Meats International (Peter Judd and Neil Teasdale)

The yield of meat on a carcass affects the profitability of all links in the production chain. We were fortunate to have the support of Metro and the breed society funds to obtain individual carcass yields. These results have been used by one meat processing company to assess the costings of internet sales of cuts of meat.

Michell Leather (Rod Meldrum and Richard Fassbender)

Michell Leather is the hide, skin and leather division of G H Michelle & Sons and is the largest producer of wet blue leather in Australia with processing plants in four states with headquarters in Adelaide. Michell Leather collected and identified hides from all 241 steers from our May 1997 slaughter. These were processed and the data analysed to examine the importance of between and within breed genetic variation on hide quality traits. Final leather quality varies greatly, resulting in huge premiums or even compensation claims once the final product is made in overseas markets.

Contact Mick Deland

Further information:
Struan Agricultural Centre