What is the link between genomics and dairy feed efficiency?

The Netherlands has become the second country in the world, after Australia, to publish a breeding value for feed intake for dairy bulls.

This valuable trait allows dairy producers to make genetic selections based on proven values of the daily feed consumption of sire’s offspring, said Roel Veerkamp, professor of numerical genetics at Wageningen University, who conducted the genomics work.  

Given the cost of feed, this finding could boost the profitability of dairy production.

“The breeding value for feed intake shows how much more or less the offspring of sires eat for their production and maintenance. By using this breeding value for feed intake in relation to the breeding values for milk production and live weight, it is possible to breed more efficient dairy cows,”​ Veerkamp told us.

The professor, who has been studying feed intake since his doctoral thesis, analyzed feed intake, DNA and pedigree of around 2,300 cows combined with data on Dutch bulls with known DNA to generate the genomic breeding value for feed efficiency.

Background​

While feed efficiency is a trait that has received much attention recently because of its importance to the economic success and environmental stewardship of the dairy industry, up until recently, there has been very little selection pressure for improved feed efficiency globally given the lack of systematic data collection for feed intake traits.

“It is costly and time consuming to measure on commercial farms, unlike milk production,”​ said Veerkamp.

Selection programs for dairy cattle worldwide, thus, have tended to focused on increasing milk production, improving milk composition and conformation, udder health, fertility, and longevity, he said.

Traditionally, the estimation of genetic merit for use in genetic improvement programs has relied on the availability of phenotypic records from the animals being evaluated or their progeny.

In the past two decades the quantity and quality of data for functional traits has improved considerably, allowing genetic evaluations for those traits. “The availability of breeding values for functional traits, together with genomic selection has allowed renewed interest in breeding for feed efficiency,”​ said Veerkamp

Indeed, genomic predictions for dry matter intake (DMI) derived from phenotyped reference populations are roughly 100-fold cheaper than predictions derived from conventional progeny testing schemes, noted a US academic in a paper​​ published in 2014.

In 2009, Veerkamp and his colleagues ran a pilot study using existing data to see if there was any merit in estimating a breeding value for feed intake.

In the following years, more research was carried out in conjunction with the Dairy Campus at Wageningen University and Research Centre and through international collaboration.

Eureka moment ​

Access to records at that dairy research facility enabled the breakthrough.

“We had already built up a library of 600 to 700 for the initial pilot study that included DNA information from blood samples, for example, but it was not representative enough to use for a genomic prediction equation. ​

“Fortunately, from 25 years of work carried out on research farms in the Netherlands, we were able to get around that limiting factor. We could incorporate and analyze additional records on over 2,500 cows including data on feed intake during lactation,”​ explained the professor.

DMI, live weight, milk, fat and protein yields were recorded for these cows. The phenotypic data was then cross referenced which each animal’s genomic values, as well as the pedigree information on previous generations.

Veerkamp is continuing to build on the results. He is leading a worldwide project to ensure wider take up of breeding values for feed intake and sharing research data across the globe.

That project, the global Dry Matter Initiative (gDMI), was initiated in 2011 at a meeting in Norway, with the goal of building an international database of dry matter intakes and genotypes of dairy cattle. It involves countries such as Canada, Denmark, Germany, Ireland, the UK, Spain, the US, Australia and New Zealand.