Genetics vs. environment: finding balance

DNA results may indicate that cattle have the potential to be productive, but the environment affects the final outcome

LONDON, Ont. — Applying new genomic technology to improve beef cattle is a noble goal, but other factors like environment must be part of the equation.

“It is tough to work this out genetically because environment has such a large part in terms of the beef industry,” said P.J. Budler of Global Livestock Solutions and Trans Ova Genetics, where he is international business development manager.

Budler has judged purebred cattle throughout the world. Originally from South Africa, he has seen a range of environments where they thrive or do poorly.

Genetic discussions are important but are just one tool to make an economically sound beef operation, he said during a technical session of the Canadian Beef Industry conference held in London from Aug. 14-17.

The four most important economic traits are fertility, longevity, adaptability and efficiency. The DNA results may indicate the cattle have that potential to be productive but the environment affects the final outcome.

An animal may have the ability to produce a lot of milk but if it is placed on marginal land, it may fail and it will also eat more to maintain itself.

“Canadians have developed a measure of balance and caution when it comes to producing,” he said.

Using genomically enhanced expected progeny differences (EPD) to select bulls can be useful but can also lead to bad decisions. They are useful if people measuring traits do it honestly and accurately.

“I think we must be careful that we don’t leave behind the need for cattle people to understand pedigrees and the need for us to trace phenotypes and merge what works and doesn’t work in a functionally efficient world,” he said.

Quoting the developer of the Beefmaster breed, he said breeding cattle is easy but the challenge is keeping it easy. Further, the worst thing that can happen to a breed is to become popular and expensive.

“Propaganda has convinced cattlemen to raise unadapted cattle with the promise of a premium,” he said.

For example, Brahmans do not do as well in Canada and Black Angus should not be on the Gulf Coast of Texas. It takes them more energy to survive and they have lower productivity or fertility when raised in an unsuitable environment.

“We have got to push back against propaganda and bring back science into the conversation. There isn’t a breed that works everywhere in the world. There is no quick fix, amazing breed that works anywhere in the world,” he said.

To say an animal has good EPDs for milk production is a subjective ranking that needs more context because its abilities depend on nutrition and climate.

Further, milk production has usurped fat content, which may be more important within the maternal breeds. Fat produces a hormone called leptin, which encourages early sexual maturity, fertility, milk and do-ability.

“All our maternal breeds in North America penalized fat when they publish the annual trait leaders,” he said.

“They have turned two incredible maternal breeds, the Angus and Hereford, into terminal breeds because they sucked the fat out of them,” he said.

“Scientists and geneticists have built a Rolls Royce. I like the science but associations and marketers need to make sure that we drive this vehicle the way it was intended,” he said.

While much of the genomics work focuses on purebred selection, it would be more useful if accurate predictions could be made for commercial cattle.

The genome is the blueprint or the script for the play, said Graham Plastow of the University of Alberta.

“What we measure in the animal or what we see in the animal is not directly the translation of the genotype because it is also influenced by the environment,” he said.

The Canadian industry uses a range of breeds and that diversity makes it is difficult to apply genomics, he said.

The commercial beef herd is crossbred and predominantly uses natural service.

DNA tests are available to check the breed makeup of commercial animals. That information can help producers decide which breed to introduce for crossbreeding and to generate hybrid vigour.

Parentage testing can also show which bulls were breeding and which were sunning themselves.

“Producers also want to know if the ones producing the most calves are also producing the best calves,” he said.

Record keeping is a prerequisite to make informed breeding decisions and build hybrid vigour.

Hybrid vigour adds to fertility, longevity and improved lifetime productivity.

Overall, fertility is the most important trait to cow-calf producers because it means they get a calf every year. That is worth 10 times more than carcass traits and five times more than growth rates.

Research from John Basarab of Alberta Agriculture and the University of Alberta shows a steady decline in hybrid vigour in the 2000s with the switch to greater use of one breed.

Research has shown that one-third of calves born and one-half of the cows could benefit from more hybrid vigour to improve their resilience and growth.

Besides promoting hybrid vigour, genetic information may identify carriers of a genetic disease so it can be controlled or eradicated.

Genetic information can identify a sire’s ability to breed daughters that stay in the herd, as well as assess an animal’s ability to tolerate environmental stress factors or diseases.

Knowing the background of steers also has an economic benefit.

Two steers may look identical but when they enter a feedlot it is hard to know by appearance alone which be the most feed efficient and grade the best.

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