Scientists working on animal genetics

Estimated breeding values (EBVs) remain a "black box" for farmers, but scientists are working to find out more about beef and sheep genetics, said Mike Goddard, from Australia's University of Melbourne and Victoria.

He talked to about 100 stud and commercial farmers, as well as beef industry stalwarts, at a Beef Expo celebratory breakfast, in Feilding, last week.

Professor Goddard said EBVs work, but there are unknown factors.

"We know how EBVs work. But the genes that contribute to them – we don't know."

He said there were many genes that contribute to factors such as growth rate, meat yield, and fertility, for example, but only one for colour.

That makes finding and marking such genes tricky, as it means all the effects are pretty small, he said.

As if that is not enough of a problem, when it comes to beef breeds, markers need to be relevant across many breeds.

"The problem is that we are measuring a marker, not the actual gene that causes the effect. The marker might be a good predictor for the gene in Hereford, but not in Angus."

Prof Goddard said that means markers have to be really close to the causative gene, that way they have more chance of working in other breeds.

People buying bulls for commercial use don't need to know about DNA at all, he said, rather they could just buy based on EBVs as they do now.

"But for stud breeders, they have to decide whether it is worth getting DNA tests for their bulls or cows in order to get more accurate EBVs."

Getting DNA tests could allow breeders to ascertain whether an animal is good far earlier than usual, Prof Goddard said.

"If you want to select a bull whose daughters are fertile, for example, at the moment you have to do a progeny test on the bull and that takes years. Whereas the DNA test is available at birth, so if you had a good test for female fertility, you could select bulls for that when they were calves."

"At the moment, tests are about $200. Our calculations say if it was reasonably accurate, that would be worthwhile."

He was hopeful the cost would come down as the test becomes more common in the future.

From the Livestock Improvement Corporation's (LIC) website, the dairy industry is using DNA results to come up with better dairy cows.

It said the concept is to select bulls for widespread use based on their DNA profile rather than waiting for information on the performance of their daughters. This process, generally known as genomic selection, results in a generation interval that's shorter by about three years.

LIC said it has put huge resources into researching genomic selection and developing its product, called DNA Proven.

Its booklet on DNA testing said with DNA Proven technology, the concept is simple, but the science is sophisticated.

It said everything they want to know about a bull's genetic merit is contained in its DNA, which can be collected from anywhere on the body.

"Bulls can be screened (or profiled), using their DNA, for any traits that we have measured in a sample of superior bulls, including production, cow fertility, somatic cell, longevity and each of the individual traits other than production."

By analysing their DNA profile, LIC said it can even rank bulls for each trait, according to how many of the favourable patterns they display.

In effect, the favourable patterns are added up, and converted into an index or breeding value. The more patterns that are considered, the better the reliability of the index.

- © Fairfax NZ News