HUNTIN' DAYLIGHT -- LOTS OF GENETIC OPPORTUNITY REMAINS

by: Wes Ishmael


Peruse the genetic evaluation of any widely-used beef breed today. Genetic progress over time, for some traits, is nothing short of remarkable. Seedstock producers continue to expand potential in some areas, while bending relationships between genetically antagonistic traits to a degree few would have thought possible just a few decades ago.

For instance, if you want low birth weights and moderate cow size accompanied by vast weaning and yearling growth potential, the genetics are there. If you're after more marbling, but want to maintain carcass yield, the genetics are available.

Genomics are adding to the reliability of genetic evaluation, especially of young cattle, while a proliferation of economic indexes are making it easier to consider multiple traits all at once.

That's the good news.

“Sadly, the current status of most national and international beef cattle evaluation systems reflects a narrow, data-driven approach to choosing traits on which to focus selection,” says Dorian Garrick, professor and chief scientist at New Zealand's Massey University. That's from comments he made at the recent annual convention of the Beef Improvement Federation (BIF).

“Bull breeders and bull buyers tend to focus more on attributes that they can easily visualize or measure, such as growth rate or calving ease, and less on attributes that are less visible in their production systems, such as feed intake during grazing, eating quality of the final product, and disease resistance,” Garrick says. “Further, they tend to focus more on traits with moderate to high rather than low heritability, and those measured early rather than late in life, as they can easily validate the effects of their selection choices within their own production systems.”

None of that is to deprecate the progress made in the easily visualized and measurable traits. It is to say those traits provide an incomplete picture of potential return, relative to the cost of production.

“Much of the selection that has occurred over the past 50 years has been driven by traits for which data collection was relatively easy. This does not diminish the importance of those traits but does constrain the selection program,” says John Pollak, professor emeritus at Cornell University and the former director of the U.S. Meat Animal Research Center. He's commonly regarded as one of the animal-breeder superstars that helped the industry get so far down the road of genetic evaluation. He also addressed the BIF gathering.

Garrick characterizes a more comprehensive approach as bio-economics driven. Think here of collecting phenotypes and developing measures for everything that impacts cost and profitability related to the system in which the genetics are employed.

“There is a logical approach to developing a breeding program that includes thorough biological and economic considerations of the traits to consider,” Garrick explains. “The first step is the formulation of the goal of the breeding program. That would normally reflect some measure of increasing satisfaction—and in an agricultural context, profitability is usually a major determinant of satisfaction…

“The second step in developing a breeding program is to define the breeding objective. This involves two components—the list of traits that influence the goal, and the relative emphasis to be placed on each of those traits. A profit-based goal should consider every trait that influences any component of whole-system income, or any component of whole-system cost.”

Yep, that's a tall order and helps explain the industry's preoccupation with the easily visualized and measureable. It also underscores potential opportunity.

Garrick believes traits that are adequately considered currently are growth and calving ease. Everything else needs more consideration.

“Namely, there is inadequate consideration of reproduction, inadequate consideration of eating quality, inadequate consideration of the human healthfulness of the beef, inadequate consideration of disease resistance, inadequate consideration of feed intake and feed efficiency, inadequate consideration of lifetime performance, inadequate consideration of welfare traits such as horns, and inadequate consideration of environmental attributes such as water use, greenhouse gas emissions, or levels of effluent, particularly Nitrogen outputs. All these characteristics exhibit phenotypic variation, and all are heritable, so could be included in breeding programs,” Garrick says.

As vexing, even if measured, all have different values to different producers.

“The beef industry is not one large integrated operation but rather is comprised of a multitude of independent businesses,” Pollak emphasizes. “There will naturally be variation in the emphasis of traits under selection. It is also recognized that, given most seedstock are sold to commercial operations within a limited radius of the seedstock operation, certain traits will be more important in some geographical regions then others. Fescue tolerance, heat or cold stress tolerance, and high-altitude tolerance are some examples of traits that would need to be emphasized di¬fferently in their respected regions. This does not distract from having a comprehensive breeding objective with a more complete portfolio of traits but rather place emphasis on the economic values of those traits when being selected within individual programs.”

Heretofore, by necessity, genetic evaluation has focused primarily on entire breed populations.

“The value of a sire or dam to create more profitable progeny can only be effectively determined by collecting data in the system or environment in which they will be used,” said Matthew Cleveland, at the BIF meeting. He is director of global beef product development for Genus ABS. “One solution to this challenge is to reduce the emphasis on developing somewhat compromised solutions that will work across the whole industry and instead focus on improving individual systems where targeted genetic improvement can have a more rapid impact, and where there is a clear incentive to collect data.”

The growing number of commercial producers conducting in-herd genetic evaluations serve as an example. They are developing selection indexes that matter most to their operation, relative to the resources, collecting the necessary phenotypic data and creating EPDs for the cows in their herd.

Exploiting What's Available

In the meantime, there is still low-hanging fruit left un-harvested by many, which gets at some of the harder-to-measure traits.

Consider reproduction.

“Due to the low heritability of most reproductive traits, many producers feel there is little that can be done through genetic management and rely solely on other management practices such as health programs and nutrition management,” says Darrh Bullock, Extension beef cattle geneticist at the University of Kentucky.

In an insightful factsheet about reproduction you can find via the ebeef.org website, Bullock explains available EPDs for reproductive traits can provide valuable, albeit limited improvement.

Depending on the breed, various reproductive EPDs currently include traits such as heifer pregnancy and cow stayability. Bullock emphasizes EPDs developed in breeds that require whole-herd reporting offer more reliability.

But, there's a faster, more effective way to improve reproduction, of course.

“The single best genetic management tool available for improved reproduction in commercial beef operations is crossbreeding,” Bullock says. “Heterosis has the greatest impact on lowly heritable traits, such as reproduction…The influence of individual heterosis on reproductive traits is improved live births and survival to weaning. Maternal heterosis positively impacts reproductive traits such as conception rate, live births and survival to weaning, along with other important economic traits.”

Keep in mind, he's talking about deliberate, planned, complementary crossbreeding.

“Traits such as reproduction and longevity have low heritability,” says, Alison Van Eenennaam, Extension animal genomics and biotechnology specialist at the University of California, in a crossbreeding factsheet available via the same site. “These traits usually respond very slowly to selection since a large portion of the variation observed in them is due to environmental factors and non-additive genetic effects, and a small percentage is due to additive genetic differences…

“Crossbreeding has been shown to be an efficient method to improve reproductive efficiency and productivity in beef cattle. The greatest impacts on profitability from heterosis are the increases in overall production and the longevity of crossbred cows.”

Van Eenennaam stresses that producers exploring specific crossbreeding systems need to consider logistics, costs, benefits and feasibility, relative to their own resources, environment and marketing.







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