What to Look for Phenotype in a Beef Cow
The Real Globe
Phenotype Still Matters
Genetic tests are available for everything from birthweight to carcass weight, so it's tempting to select your next herd balderdash based on those results alone. Just think, no more driving all across the state to expect at pen after pen of yearling bulls. Or, you could build your dream herd of females off a spreadsheet of genetic predictions for maternal traits. And so again, maybe non.
"Phenotype is more critical now than ever," seedstock producer Dave Nichols says. "Information technology is what you can run into and measure. In order to brand cistron discovery for growth and carcass merit, we have to have birthweight, weaning weight, performance and ultrasound or carcass information. Genomics add together to the accurateness of what we already know."
As an example of the importance of phenotype, the Bridgewater, Iowa, cattleman cites a multiyear National Beef Cattle Evaluation Consortium (NBCEC) written report designed to discover genetic markers for susceptibility to bovine respiratory affliction (BRD), or pneumonia.
Researchers first identified ill cattle the one-time fashioned way, by observing them. Then, they took nasal swabs to confirm the diagnosis. Without first identifying sick cattle past phenotype, they probably wouldn't be able to notice genetic markers responsible for resistance to the costly disease.
Phenotype The Bull
Simply as phenotype continues to be disquisitional for researchers, it should besides exist high on producers' lists when selecting bulls.
University of Georgia animate being scientist Ronnie Silcox stresses "even genomically enhanced, expected progeny differences (GE-EPDs) don't tell you everything yous need to know. When I talk to commercial producers, I tell them EPDs are the get-go thing they need to look at. Use them to narrow down to a smaller group."
Down to a manageable few, make the concluding balderdash pick with the eyes of an experienced cattleman.
"They must be functionally sound," Silcox says. "Do both eyes piece of work? Look at their feet and legs. Make sure they've had a Convenance Soundness Exam. Information technology doesn't matter how good a bull is, he's not going to do you any proficient if he can't go a cow bred."
And, because most commercial producers sell feeder calves, Silcox says it'due south important to consider whether a balderdash has enough muscle to grade like a No. 1 feeder dogie. The same approach applies when selecting replacement heifers, whether those heifers come up from your ain herd or another producer. Narrow your selection using EPDs, then look hard at the heifer. If she can't carry and raise a calf, she isn't going to help your herd.
A Potent Combination
Phenotype continues to be vital in cattle selection. Even so, it's the combination of EPDs and phenotype that'south moving herds to the next level. "EPDs are meliorate than they've ever been. If y'all add the results of Deoxyribonucleic acid tests to actual performance information, it can increment the accuracy to that of a balderdash that has produced viii to ten calves," Silcox says, describing what's commonly known in the industry as GE-EPDs.
Consider a calving-ease yearling bull to utilise on heifers. If all you have are EPDs based on full-blooded, and he is an embryo-transfer calf (his ain birthweight doesn't gene in) expect accuracy of but five%. Add together genomic exam results to that, though, and accuracy can shoot up to around 40% for the aforementioned bull.
The less heritable the trait, the more than genomic testing tin improve accuracy. Auburn University animal scientist Lisa Kriese-Anderson says, "With lowly heritable traits like the reproductive traits, fertility, gestation length, historic period at first calving, genomic testing increases the accuracy of the EPD value as if the animal has had x to 12 calves on the basis."
She says with the moderately heritable traits like weaning weight and average daily gain, calculation genomic test results to the EPD analyses is similar looking at 5 to 8 progeny of the creature. With highly heritable traits like carcass traits, or rib-middle area, marbling and fat thickness, genomic tests increase the accuracy at a charge per unit of 2 to three progeny.
Even with this boost in accuracy from GE-EPDs, Kriese-Anderson believes, like Dave Nichols and Silcox, that there remain compelling reasons to keep phenotype in the selection process.
"We don't know what every gene in the bovine genome is doing yet. We observe a console of markers that go with a trait, only non every gene that affects that trait is known. We all the same need actual measurements," she says. "Not every purebred fauna will get DNA-tested. Nosotros have to have the phenotype data to validate and compare with the genomic information. Someday, we may be able to just take DNA samples. Merely for now, nosotros need both, and that's OK."
(BAS/SK/ES)
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Source: https://www.dtnpf.com/agriculture/web/ag/livestock/article/2018/09/17/phenotype-still-matters
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