“They created hard-keeping, high-maintenance cows that struggle to reproduce under what was once considered normal ranch conditions. And some breeds and individuals (especially crossbreds) tend to be more fertile than others even if they have a lower body condition score.Īs the majority of beef producers selected for more growth and less back fat, they inadvertently selected for lower fertility. Since fleshing ability and maintenance requirements are heritable, fertility is also very heritable. Reproduction cannot take place until maintenance requirements have been met and cows are storing energy reserves as fat,” says Pharo. “Fertility is more a function of fleshing ability than anything else, and fleshing ability is a function of low maintenance requirements. In the real world, however, nothing is isolated,” he says. If you were able to isolate fertility from everything else, then that assumption might appear to be true. “For at least 50 years or more, academics have told us that heritability of fertility is very low–so low that we shouldn’t waste our time selecting for it. “Ironically, the beef industry has been selecting almost exclusively for growth and carcass traits, at the expense of reproduction,” says Kit Pharo, a seedstock breeder in Colorado. Yet fertility is usually not at the top of the list when producers are selecting replacement heifers. Before you can sell a calf, or have that calf perform well in the feedlot, or produce a carcass that brings a premium at harvest, a cow must first get pregnant. Studies have shown that reproductive traits are twice as important as growth traits, which are more important than carcass traits. Any of these factors can affect the fertility of the individual animal, or the herd.Ĭow-calf producers who make a living from their cows know fertility is the most important economic trait. Whether a heifer will breed quickly (reaching puberty at a young age) or a cow breeds back quickly after calving depends on a combination of genetics, nutrition, general health, reproductive disease, etc. There are many factors that influence fertility.
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