Cow and Heifer Genomics
Genomic testing is the process of analysing a heifer's DNA - such as in ear tissue or a tail hair - to reliably predict her future performance in the herd.
Genomics can be conducted as early as birth, so farmers can make informed decisions about a heifer’s role in their herd. DNA samples are easy to collect and can be taken at the same time as routine husbandry procedures, such as ear tagging or disbudding.
You ask, we answer on heifer genomics
Below are some commonly asked questions about heifer genomics that have been submitted and answered by our experts.
Frequently asked questions
Q: I have just bought some heifers and am wondering if I can still genomic test them, even though I know nothing about their pedigree?
Yes, you can still genomic test these heifers. The reliability of the Australian Breeding Values (ABVs) generated will be lower than if the pedigree was known. For example, providing the correct sire can improve the reliability of an animals Balanced Performance Index (BPI) by up to about 15%.
Q: Is genomics only for purebred Holstein and Jersey herds?
While genomic testing first started in Holstein and Jersey cows, it has been extended in 2021 to include red breeds and their crossbreeds. These three breeds cover 95% of the Australian dairy cow population. Purebred or crossbred animals sired by a Holstein, Jersey, Aussie Red, Ayrshire or Illawarra bull can be genomically tested. There isn’t enough domestic data to calculate genomic values for Brown Swiss and Guernsey but you can contact DataGene for information on international platforms that cover these breeds.
Q: I’ve got calves sired by my herd bulls, how useful is genomic testing for them?
Calves sired by herd bulls can be genomic tested. Knowing the breed of the bull is important, and ideally a sample from the bull itself would be genomic tested as well. Genomic testing can provide information on how good the bull is for breeding future replacements, and also helps you to identify which calves that bull has sired. This is important if you are running multiple herd bulls.
Q: I tested my herd and got negative BPI numbers – does this mean the results aren’t accurate?
The reference point for the BPI numbers is drawn from the average of artificially inseminated cows born within five-year period. This is called the base – and includes cows born between 2009-2013. If you have a negative BPI value, it means the tested cow is below average compared to that reference group. Whatever the starting point is for a herd, there is an opportunity to rapidly make improvements, each year, by using bulls from the Good Bulls Guide and genomic testing your heifers.
The reliability percentage is what tells you how confident you can be in that animals Australian Breeding Values. The more information you have about an animal and it’s relatives, the higher the reliability percentage.
How genomic testing works
Genomic testing allows farmers to:
Save money on rearing costs by not rearing heifers that are unlikely to perform.
Make more informed decisions on which heifers to sell, when using sexed/beef semen and when purchasing females.
Significantly fast-track genetic improvement in the herd for traits of importance such as fertility, type or A2/A2.
In herds where no surplus heifers are available, farmers may also consider selling less desirable heifers and replacing them with higher quality, genotyped heifers. If using this approach, it is important to consider the biosecurity risks associated with purchasing animals.
Genomic testing is an important tool for accurately determining animal identification and parentage and reducing pedigree errors that are known to occur in around 15% of animals. Testing is also a straightforward way to establish pedigrees in herds that do not have adequate records or do not have time to construct pedigrees.
The reliability of genomic testing of heifers at a young age is the equivalent of having data from seven lactations (Figure 1). Compared with breeding values based on pedigree alone, this is more than double the reliability.
Figure 1. Reliabilities of genomic ABVs for heifers and 7th lactation Holstein cows (source DataGene, 2017).
Currently, genomic testing can be done for any Holstein, Jersey, or Jersey-Holstein cross animal whose sire has an Australian Breeding Value (ABV).
The use of genomic testing of dairy heifers is rapidly increasing in Australia. The most recent data shows that over the past 12 months, commercial genotyping of females in Australia rose by more than 60% compared to the total number in 2018/19.
Dairy genomic technology was initially developed in research programs by world class Australian scientists utilising data from more than 30,000 genotyped animals, 30 years of progeny testing, herd recording, type classification and genetic evaluation programs. These research programs, including DairyBio, were funded by Dairy Australia.
How to collect samples
Samples for genomic testing are easy to collect and can be taken at the same time as routine husbandry procedures such as ear tagging or disbudding. To obtain Tissue Sample Units (TSUs) and pliers or hair sample cards, contact your genomic service provider.
Figure 2. Collecting an ear tissue sample for genomic testing using a Tissue Sampling Unit (TSU)
Farmer case studies
The case studies below are designed to demonstrate how Australian farmers are implementing heifer genomic testing in their own businesses.
- Andrew Cavill, South Australia: Simple sire selection helps put 'fun' back into breeding
DataGene is an independent and industry-owned organisation that is responsible for developing modern tools and resources to drive genetic gain and herd improvement in the Australian dairy industry, through research, development, and extension activities.
For more information about genomics, visit the DataGene website.