| GENOMICS | WORDS // DAIRY AUSTRALIA
The DNA Difference, How Genomics Can Help You Pick Your Best Animals I
NCREASING numbers of Jersey breeders are using genomics to better target their sexed semen, with the information from DNA testing providing another tool to assist on-farm decisions. This comes as recent DataGene analysis of Jersey heifer calves revealed an average difference in Balanced Performance Index (BPI) of $276 between the best and worst animals within individual groups. No group of calves in this analysis had a range that was less than $100 BPI between the genetically superior and inferior animals, showing the importance of retaining the best heifers to achieve the most genetic gain. The BPI is an economic index used by DataGene to measure the lifetime contribution of vital genetic traits such as production, type, health, fertility, longevity, workability, and feed efficiency to a farm business. DataGene Project Lead – Genomics Michelle Axford crunched these Jersey numbers and said the range in the BPI and Australian Breeding Values (ABVs) demonstrated the value of using genomics to make more informed decisions. “The main thing these numbers are telling us is that there is enough difference in groups of Jersey calves, that we need to genomically test to distinguish the top from the bottom,” she said.
“It’s risky to select calves at a young age without genomic data. Choosing the wrong heifers to breed replacements from, or to sell, can leave a costly and lasting impact on a herd.” Genomic testing reliably predicts the future performance of young heifers as the test results are the equivalent of having seven lactations worth of data. Michelle said many farmers have been surprised with their calves’ genomic results, as in calf pens the individual animals aren’t considered as being too different. The DataGene analysis included Jersey calf cohorts born after 2019. These animals came from 64 groups of calves and the average number of calves per group was 51. These calves had an average BPI of $145. The best and worst animals had an 11 per cent difference in Daughter Fertility and 10 per cent different in Mastitis Resistance. “An investment of about $50 per calf for a genomic test sorts these differences out at a young age,” Michelle said. “And then you have the genomic information to use for the lifetime of the calf.” For context, the difference between the best and worst Holsteins for a six-week in-calf rate is 19 per cent. This larger number reflects a variation of traits in Holsteins compared to Jerseys.
A recent analysis of Jersey heifer calves revealed an average difference in Balanced Performance Index (BPI) of $276 between the best and worst animals within individual groups. Genomics allows farmers to identify the top calves to keep as replacements and consider options for the bottom ones. Photo credit: Dairy Australia. The Australian Jersey Journal – November-December 2021 // 10
