If you’re a commercial beef producer in Western Canada, generally speaking, you’ve got a herd of crossbred cows. That means Gentec’s Replacement Heifer Profit Index (RHPI) Score™ should be one of your go-to tools. Why? It speaks to selecting replacement heifers with an optimal level of hybrid vigour, fertility, longevity and lifetime productivity.
A study (as reported in The Western Producer) led by Jared Decker at University of Missouri-Columbia, tells a good news story about the sires’ gEPDs and the predicted outcome in the feeder progeny. Using an Angus database as a starting point, Jared found relationships between sire gEPDs and the outcome in commercial cattle, giving the GeneMax tool a suite of gEPDs for weaning weight, carcass weight, marbling, ribeye area, among others. But… all for Angus crossbred cattle, and not for feed efficiency.
What does Gentec do differently?
“We didn’t want to repeat what each breed association would do so we concentrated on crossbred females mated to purebred and crossbred bulls common to western Canada. This also included the crossbred offspring, and was our starting point. Commercial cattle first,” says John Basarab, Gentec’s Director of Beef Operations. “So our database has a high percentage of Angus, Simmental, Charolais, Limousin, Hereford, Gelbvieh and other crossbred females and feeder cattle offspring. And our purebred database (bulls) for determining genomic breed composition and retained heterozygosity has 14 breeds. That’s quite different right off the bat.”
While the GeneMax tool concentrates on growth and carcass traits, it’s missing something that Gentec has been working on for over 20 years: feed intake and feed efficiency or dry matter intake (DMI) and residual feed intake (RFI). So again, Gentec’s reference database contains lots of phenotypes with genotypes for DMI and RFI, from which it developed molecular breeding values (MBVs) for DMI and RFI that most other genetic evaluation companies and breed association don’t presently offer.
Another key difference has to do with replacement heifer selection. Breeding values and maternal indexes for most purebred associations select for the genetic merit of the daughters produced from the sire and dam. Trait gEPDs in the maternal index usually include calving ease, growth traits (e.g., wean weight, direct and maternal milk, residual ADG), and heifer pregnancy. But that’s down the road quite a bit. The female calf has to be born from a single, unassisted birth early in the calving season, grow well from birth to yearling, and be from a mother with many retained daughters in the herd. But the line on the 50-year genetic trend for heifer pregnancy EPD is flat (!!) indicating not a lot of progress made. So Gentec has focused on the immediate need of selecting for PRESENT replacement heifers, not future daughters. In that case, hybrid vigour is very important, especially since, as identified by Gentec’s RHPI Score, it’s related to higher pregnancy rates and lifetime productivity.
“Clients have been “fascinated with the breed composition and gEPDS. It’s been an invaluable asset for our consulting practice and is adding value for the customer,” says Waylon Wise, veterinarian and owner of Cow/Calf Health and Management Solutions.
Most genomic evaluations concentrate on the “additive” genetic effect, where a single nucleotide polymorphism (SNP, pronounced “snip”) with 2 B alleles is better than 1 B allele, and better than no B alleles at all. This approach is particularly effective for moderate to moderately-high heritability traits like growth, feed efficiency, behaviour and carcass traits. However, traits with low heritability (like fertility and general fitness) are more influenced by the non-additive genetic effects of dominance, epistasis and genomic diversity, all related to hybrid vigour. General health and resilience to environmental stress (that is, hybrid vigour) are becoming more important, especially in the context of our rapidly-changing climate where animals need to be more resilient to extremes. This is an important component of Gentec’s index score.
“We concentrate on commercial crossbred cattle,” says John. “Then on providing what that producer is asking for—a replacement heifer that gives a calf during the first calving season at 2 years of age and stays in the herd for at least 5-years… a very tall order. We know that commercial producers don’t keep the best of records, and they definitely don’t keep pedigree information. Doing things using DNA or from a genomics point of view just has many advantages.”