Improvements in genomics create better traits in cattle

Big data and the recent sequencing of the bovine genome have given dairy farmers the ability to choose which animals to breed based on an abundance of information unthinkable just a few years ago.

Breeders are already making more educated decisions at the birth of a cow or bull on whether its progeny would be likely to have desirable traits like productivity, fertility and good health.

"Big data about genomics are bringing us the ability to predict genetic traits in ways we haven't been able to before," said Alison Van Eenennaam, University of California, Davis, animal genomics and biotechnology specialist. "This is possible because we sequenced the bovine genome in 2009, and found the tremendous variations."

Van Eenennaam made her remarks at the Golden State Dairy Management Conference in Stockton.

"As an animal breeder, your choice is which animals are going to be the parents of the next generation," she said. "That's pretty much what you do."

It has become far easier and more economical to genetically test the animals at a very young age to make informed decisions about which to breed.

"Since 2009, we have sequenced thousands of bovines," Van Eenennaam said. "The amount of data in that database is 90 trillion bits of data. We can use this information about variability to make genetic selections."

This wealth of data has made it possible for breeders to continually improve the quality of the animals at a much more rapid pace.

"Breeders used to take what they thought was a good bull and see what daughters he produced," Van Eenennaam said. "It would take five years to see, because you would have to wait until his daughters had calves before you could learn about the milk they produced. You can now do a DNA test on an animal and make predictions."

Genetic tests of the very young animal can be compared with a mountain of records on which animals in the past produced the most milk, or the most offspring.

"The younger you can use an animal to produce the next generation, the faster you can improve the population," Van Eenennaam said. "You can look at which of the markers in an animal are associated with better fertility or milk production. You can take an animal that was just born and see its genetic worth by seeing which snips it inherited from each of its parents."

As researchers develop an ever-expanding body of data on the performance of animals related to their DNA samples, these predictions will continue to become more accurate, she said.

"We're going to get much better at predicting which animals are going to be better in terms of all the traits that make for genetic value," Van Eenennaam said. "The future is big data."

This future is already here for the most common breeds, because there is already a substantial library of information on which animals produced the most milk and offspring.

"The Holsteins and Jerseys are going to be more accurate because we have more animals in those databases," Van Eenennaam said. "The rate of genetic gain in Holstein bulls has doubled since the introduction of genomic selection in 2009. You're going twice as fast."

The average value of a Holstein bull on the market is increasing at a rate of more than $80 a year, while at the turn of the century the increase was less than $18 a year.

The availability of more information about the animal at a much younger age is expanding the criteria used to judge the value of the animal.

"With this advanced ability to select for desired traits, it becomes more important to know what traits you want," Van Eenennaam said. "The USDA chart on desirable traits has gotten much more detailed and complex; it is no longer just amount of milk and fat."

While there is already a substantial amount of data on record of the productivity and longevity of the animals, along with samples of their DNA, researchers are just beginning to accumulate information on which animals are most likely to contract important diseases.

"We are just starting to develop a database of which animals developed which diseases," Van Eenennaam said. "Without records of diseases going back to the USDA, there is no way to develop predictions for which cows will become diseased."

As the list of characteristics grows longer and more complex, breeders will have to make more complex choices about which qualities they deem most important.

"If you put a lot of pressure on health traits, you're taking it away from fertility, milk production and other important traits," Van Eenennaam said. "Health is important, but it is one factor that needs to be balanced. If you put a lot of emphasis on health, it is going to be at the expense of other traits."

(Bob Johnson is a reporter in Davis. He may be contacted at bjohn11135@aol.com.)