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Calving-ease Cows: Optimal or Extreme? Source: Beef Improvement Federation Selection for calving ease often results in decreased calf birth weights, but what are the consequences of selecting heifers based on easier calving and lighter birth weights?
Bennett explained relevant USMARC research during the Advancements in Efficiency and Adaptability breakout session of the 2021 Beef Improvement Federation (BIF) Research Symposium Seedstock breeders and & Convention hosted June commercial cattle producers 22-25 in Des Moines, Iowa. often apply genetic selection for According to Bennett, studies calving ease to reduce calving involved lines of cattle selected difficulty among first-calf for calving ease and control heifers. Scrutiny may be applied lines, with all followed through to selection of replacement their fourth calving. Selection females and the sires to which for similar yearling weight was they are mated. According to applied to cattle from select and Gary Bennett, a recently retired control lines. Bulls representing U.S. Meat Animal Research their respective lines were used Center (USMARC) scientist, on heifers, but the same bulls direct or indirect selection were used on both lines, as of calving ease often results cows. in decreased birth weight of “The principal question calves. But what might be the addressed by this research is consequences when heifer whether a genetic difference calves are selected on the basis in calving ease, independent of their genetic potentials for of growth to yearling age, easier calving and lighter birth had negative effects on cow weight? productivity,” reported Bennett.
Sharing the results, Bennett said cows from the select lines representing calving ease exhibited lighter mature weights, smaller hip heights, and the potential for lower maintenance costs on a per cow basis. Select line cows tended to wean more calves and stay in the herd longer. Select line females were assisted significantly fewer times at calving and, through their years in the herd, produced more pounds of weaned calf. Weaned calf weight per heifer starting the system was significantly greater for the select line due to greater survival rate among their first calves and greater calving success subsequently. Noting the value of cull animals, Bennett reported that while mature weights were lighter in select lines, marketable cow weight was nearly identical to that of
control line cows. Control lines did offer more marketable young cow weight, but select lines yielded more old cow weight. “No important unfavorable effects of genetic differences in calving ease were identified in this experiment,” stated Bennett.”
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