Genomics involves the use of DNA information to reliably predict the future performance of young bulls, and for selecting superior cows to breed replacements. Using genomics as part of your breeding decisions is far more reliable than selecting by pedigree.

Genomics analysis is primarily done from a hair sample and this allows the testing to be done at a young age. This analysis is used to calculate Australian Breeding Values (ABVs) for a range of traits and indices which enables the farmer to choose sires and heifers based on the characteristics that match their breeding objectives.

Genomic testing is conducted on most AI sires active in Australia for ease of selection and more farmers are having their heifers tested as well – enabling informed early classification and culling decisions according to breeding objectives – which can save rearing costs and allow top heifers to be reserved for their AI program to gain fast genetic improvement in the herd. Genomics can also be used to confirm parentage, for ease of export and for stud owners to register animals.

DairyBio – which is a joint venture of Dairy Australia, Agriculture Victoria and the Gardiner Foundation – has a number of projects working on developing new and improved ABVs for Australian dairy farmers. Dairy Australia continues to invest in this research as genetic improvement is vital to the future productivity and profitability of the Australian dairy herd.

In April 2020 eight ABVs identified or improved by DairyBio were added by DataGene to the ABVs in the Good Bulls Guide. The guide assists farmers and semen resellers to select semen suited to a farm’s breeding objectives and increase productivity and profitability through genetic gain. The Good Bulls Guide contains the top available bulls that meet the minimum criteria for Balanced Performance Index (BPI) and reliability. The BPI combines productivity, type and health traits for maximum profitability according to the dairy farmers objectives.

Kevin Argyle, Director of Major Innovation Projects for Dairy Australia and co-director of DairyBio said “With DairyBio leading the research the BPI is Australia’s flagship national animal selection index. Using genetically superior sires can improve gross margins – cows with higher BPI produce more milk and last longer in the herd compared to lower BPI cows”.

The 2 new and 1 improved ABVs are:

1. Gestational Length ABV: The gestational length for a calf is mainly dictated through the genes of the Bull the cow is mated to, this is a natural variation. Most bulls fall into the ± 2 days category, but some bulls can have as much as 11 days shorter gestation period effect.  By selecting bulls with a shorter gestational length ABV a farmer can manage the herd calving spread more efficiently. To breed for shorter gestational length select a high BPI bull from the Good Bulls Guide that has a Gestational Length ABV of less than zero – the further from zero the number the shorter the gestation.
2. Mastitis Resistance ABV: is a multi-trait ABV – utilising udder depth, somatic cell count and clinical mastitis records. Due to low hereditability of mastitis, management practices and environmental conditions have a higher impact, but for farmers the Mastitis Resistance ABV is another tool in their belt. To breed for improved mastitis resistance, select a high BPI bull from the Good Bulls Guide with a Mastitis Resistance ABV of higher than 100.
3. Calving Ease ABV: updated with improved reliability and almost all Holstein bulls will receive a Calving Ease ABV. To reduce difficult calving choose Bulls with a Calving Ease ABV of at least 103

The five improved composite type (cow structure) ABVs are:

1. Overall type (updated): this is an updated model for the overall type.
2. Mammary system (updated): combination includes the mammary score, udder depth, teat length, fore attachment, fore and rear teat placement, rear attachment height and width, udder texture and central ligament.
3. Dairy Strength ABV (composite): combination includes dairy Strength score, stature, udder texture, muzzle width, body depth, chest width, angularity and loin strength.
4. Feet and Legs ABV (composite): combination includes feet & Leg score, foot angle, heel depth, rear set, bone quality, rear leg view.
5. Rump ABV (composite): combination includes rump score, pin set, pin width and loin strength