Shepherds are utalizing EBVs to improve their flocks
When shepherds evaluate an animal for its potential to be added to their flock, typically the first thing they do is take a good look at the animal. Though an important step, visual assessment fails to reveal all of an animal’s merit. If shepherds want to select animals based on more than what they can determine by looking at the animal, they may utilize Estimated Breeding Values (EBVs) to guide their decisions.
EBVs are relatively new and used by some, but not all, sheep breeds. They are similar to the Expected Progeny Differences (EPDs) used in the cattle industry. EBVs help to predict the performance of an animal’s future offspring. The National Sheep Improvement Program (NSIP) supports producers interested in obtaining EBVs for their animals.
Values are assigned to ewes and rams that predict differences in the performance of their offspring. EBVs evaluate growth traits, wool traits, carcass traits, reproduction and parasite resistance.
“There’s been an increase interest in wanting to know what EBVs are and how they work,” Chelsey Kimbrough, Ph.D., livestock specialist with the University of Arkansas System’s Division of Agriculture, said.
Most commonly, EBVs are generated by sending in performance data of animals that have been measured in the same contemporary group. Researchers analyze the data to identify the difference in performance in contemporary groups and look at the relationships in parentage. According to NSIP, EBVs are calculated on the performance of the individual animal, related animals in the same flock and related animals in other flocks.
From that analysis, researchers can determine what percentage of the difference in the animal’s performance is due to actual genetic differences and which is due to environment.
“Every time we go in and measure an animal’s weaning weight about 30 percent of it is a genetic value and 70 percent is environmental in what we see,” Alan Culham, director of operations with Katahdin Hair Sheep International, said.
EBVs allow producers to compare animals on a genetic level. Utilizing EBVs gives producers the ability to combine sound management with good genetics. “What we need to do is get rid of that camouflage of the environment and the management, and look at what is truly a genetic feature of that animal,” Culham added.
If producers are looking for a specific genetic trait to help them better their flock, EBVs can help guide animal selection decisions. This could be beneficial if a producer is deciding be-tween two animals that look similar and have a similar phenotype. The shepherd could consult the EBVs to guide in the decision.
Commercial producers do not have EBVs for their sheep because they manage unregistered flocks. However, commercial producers still may want to take a look at an animal’s EBVs if they are purchasing a purebred ram for their flock.
Industry leaders are working to improve the accuracy of EBVs. Even with excellent records, it can take years to get solid EBVs on a ram. “All we know about that animal when it is born is what it’s parents have done,” Culham explained.
“You can’t find out how a ram’s daughters are going to produce until we get them into production which can be four or five years.”
Culham and other experts are working with researchers to develop genomically enhanced breeding values for sheep. The enhanced breeding value evaluates information about the ani-mal and its DNA to make a prediction of the animal’s genetic merit.
“By using the DNA and enhancing those breeding values, we can get that information a lot quicker, which allow us to decrease generation intervals and make progress more rapidly,” Culham explained.