Producer Applications Committee
Hair Shedding Rate May Affect Weaning Weight
COLUMBIA, Mo. (June 29, 2010) — How quickly cows shed their winter coats in the spring may have an effect on their calves’ weaning weights. Research led by Trent Smith, Mississippi State University, with funding from the American Angus Association, shows a probable link between the two.
Trent Smith“The objectives of this three-year study were to develop a method to measure hair shedding, determine the variation in shedding and estimate shedding’s effects on 205-day weights and body condition scores (BCS),” says Smith. “We observed 532 cows from 2007-2009 in North Carolina and Mississippi to determine if the perception is true that cows who do not shed or shed later are not good performers. Cows seem to perform better when they are in a thermo-neutral zone (TNZ), where heat stress does not suppress reproduction, milk production and appetite.”
A 1-to-5 scoring system to describe hair shedding was established, and visual evaluations were done by the same technicians on a monthly basis from March through July. Data analysis revealed that BCS was not significant, so researchers focused only on weaning weights. In the adapted score analysis, Smith found that cows that shed by May had, on average, 589-pound (lb.) calves. Cows that shed after May had, on average, 565-lb. calves, for about a 24-lb. difference.
“What we concluded is that cows that shed later weaned lighter calves, but more data is really needed to confirm the findings," Smith said. "We believe hair shedding is moderately heritable, which means it may be possible for producers to select for this. There is some variation."
Smith further notes that animals with little or later hair coat shedding might be good candidates for culling, especially in the Southeast where the evaluations were made. However, more studies are again needed to determine if the advice would be the same for other environments. In addition, researchers would like to consider the effects of prolactin concentrations, hair regression, changes in the type of diet and temperatures to assess the rate of shedding.
“Our next steps would be to try the same observations in different (geographic) areas, as well as see if any other traits are related to hair shedding,” says Smith. “Over the three years, these results were repeatable. The same cows tended to shed at about the same time each year. We would need to find out if that is true in other environments.”
Smith spoke in Tuesday's Producer Application Committee session at the 2010 Beef Improvement Federation (BIF) symposium. Themed "Gateway to Profit," the 42nd annual research symposium and annual meeting was hosted by BIF June 28-July 1 in Columbia, Mo.
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