How farmers can use genomics to improve breeding

Farmers Weekly spoke to geneticist Darren Todd about genomics ahead of his upcoming talk on the subject at UK Dairy Day on 13 September.

Dr Todd is a geneticist for the National Bovine Data Centre (NBDC), a role which involves helping farmers interpret and make the best use of data on genetic merit, inbreeding and genetic defects.

How can farmers use genomics?

They can test young animals to get an early estimate of their genetic merit and then use this information to decide which to keep as replacement females or potential stockbulls.

The information also helps make more informed mating decisions for young heifers.

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The information also helps make more informed mating decisions for young heifers.

How many UK farmers are using genomics?

Most dairy farmers use AI bulls that have been genomic tested, about 80% of dairy-sired calves are fathered by these bulls. 

Uptake is much lower on the female side with only a few percent (2-3%) of dairy females being genomic tested.

How many animals are on the UK database?

About 1 million live animals and 10s of millions of ancestors.

What is GPLI?

GPLI is commonly used to refer to profitable lifetime index (PLI) for genomics tested dairy animals. PLI is a weighted index of individual trait genetic merit.

What is GTPI?

Genomics total performance index is an overall genetic merit index calculated for dairy animals on the US’s genetic base.

What is the difference between the two?

The most important difference is the individual trait genetic merit that makes up these two indices.

The traits used in GPLI are calculated with reference to a database of phenotypes measured on UK farms.

These phenotypes (for example, milk records) are influenced by the environment – so the resulting genetic merit is an estimate of breeding worth in the UK farming environment.

GTPI uses data from the US and so is relevant to farming conditions in that country.

How valuable are genomics for farmers who do not breed pedigree cattle or show animals?

Genomics can help any type of farmer know more about the genetic merit of their young cattle. The technology is particularly good at identifying genetic merit in low-heritability traits such as health and fertility which are key to many commercial dairy farmers.

What kind of traits should commercial farmers look for in genomics?

Overall indices such as PLI and type merit (TM), should be the starting point when looking at genomic data. Farmers may then wish to focus on individual traits such as milk kilogramme or fertility, depending on their breeding goals.

PLI is pretty good at identifying all-round bulls for health and fertility so anything more than £500 is likely to be strong in those areas and there are plenty of AI bulls on the market at that level so they should be competitively priced.

If you’re trying to capitalise on milk solid contract offerings, what sort of traits can you select for using genomics?

Percentage fat and protein, as well as kilogramme fat and protein, will be key here, but farmers should still pay attention to overall indices such as PLI and (TM) to make sure they pick animals with all-round genetic merit.

There’s no point in selecting for higher fat percentage for example if the teats are too short to keep the clusters on.

How accurate are these measures and does reliability change with the age of the animal?

Genomics testing of young dairy animals can estimate between a half and two-thirds or their genetic merit depending on the trait involved.

This reliability will increase over time as they get information from their own milk records classification and eventually progeny.

How can you spread risk when relying on genomics? Should you use more than one genomic bull within the herd?

Absolutely, perhaps consider using three young genomics bulls over the same number of cows that you would have used one daughter-proven bull.

Will more genomic information be available in the beef industry soon?

Genomics information is available to beef farmers but, in general, their use of genetic merit data is limited in comparison with dairy farmers.

If the supply chain starts rewarding, for example, meat quality traits, then I think beef breeders will be driven to make more use of genomic data.