Background
The current MLA funded Genetic Resource Flock (GRF) began as the Sheep CRC’s Information Nucleus Flock (INF) in 2007. Over five years, the INF gathered a massive database of biological and genetic information by joining 5000 ewes each year to about 100 industry sires chosen for their genetic diversity. The sheep were run as five sub-flocks, spread over eight research stations around Australia. One of the largest sites was near Katanning at Great Southern Agricultural Research Institute (GSARI) in Western Australia. Other sites included Struan and Turrettfield in South Australia, Hamilton and Rutherglen in Victoria and Trangie, Cowra and Armidale in New South Wales.
The Sheep CRC also contributed to educating the next generation of livestock scientists through their postgraduate program. More than 30 students utilised data generated by the INF in their post graduate studies. These young people will continue to shape the future of the sheep industry. The science that has been delivered has and will provide ongoing benefits to industry.
The current Genetic Resource Flock
Currently, the GRF project includes only two flocks, one in Katanning, WA and one in near Armidale, NSW. Both flocks are used to progeny test industry sires that are also trait leaders for a variety of meat production traits that cannot be measured on live animals.
Approximately 1000 ewes are inseminated with semen from about 100 industry sires at each site. The lambs are tagged with an electronic identification number at birth and mothered up with its dam. This technology has made it possible to collect much more data faster and more accurately on individual animals. All lambs that are stillborn are also recorded as lamb mortality, which is the greatest point of inefficiency in sheep production systems. Learning why lambs die is an important step in understanding how to address this problem.
A wide range of visual traits such as body conformation and structure are collected at marking, weaning and prior to slaughter. Soon after weaning, the lambs are allocated to one of three management groups. A wealth of data is recorded on each sheep prior to slaughter. This includes body weight and condition score from birth to slaughter and additional traits such as worm egg counts, scanning for eye muscle and subcutaneous body fat.
At slaughter, carcass weights are recorded, as well as a range of measurements including various fat depth and eye muscle measurements, meat colour and pH. Meat samples are collected and tested for a wide range of meat quality traits that may impact on consumer preferences. All data is stored in a central database managed by Sheep Genetics. Because Sheep Genetics also uses information from relatives of the sires that were progeny tested, the data influences the values and accuracy of sheep related to the sire. In this way, rams that contribute semen to the GRF have a much wider influence on ASBV than just their own performance. This has seen significant improvements in the accuracy of ASBV of sires, especially for carcass and meat quality traits that are difficult to measure on live animals. Blood and other tissue samples are also collected from each lamb and used to extract DNA. The results are used to identify genetic markers associated with production traits on individual sheep.
A major focus for the GRF is developing more accurate genomic breeding values. This technology has improved accuracy when identifying superior breeding animals for Australia’s future sheep flock at a younger age and will continue to do so as more data is being collected, and as more genetic markers are found. At present, sheep DNA is tested using a 15K SNP (single nucleotide polymorphism) genotyping test to identify which genetic markers a sheep carries. This chip also includes genetic markers to determine an animal’s pedigree and its true poll/horn status. This technology is used to estimate a genomic breeding value for traits that are too difficult or expensive to obtain in other ways.
The GRF project will continue to benchmark key industry sires through progeny testing, which will benefit industry through improved sheep genetics.