The most common cause of infertility in beef herds is poor cow nutrition. Over conditioning can also be detrimental, especially in heifers, but is far less common a problem. Body condition before calving, after calving, and at breeding can all contribute to infertility. Cows that calve thin but are gaining at breeding will have better conception rates than cows that remain thin. However, cows that maintain good body condition throughout pregnancy will have the best chance of breeding back. Most commonly protein and energy are deficient in beef cattle diets. But vitamin and mineral deficiencies can also cause infertility. Copper is deficient in forages in parts of LA which can lead to deficiencies in animals. Infertility, poor vaccine response, diarrhea, weight loss,poor growth, weak calves and calf health problems can all stem from copper deficiency. Stress can cause pregnancy wastage at any stage of gestation. Low stress handling when processing cattle will
minimize this problem. Heat stress is also a major cause of infertility, especially early in pregnancy. High humidity exacerbates heat stress and would be expected to impact conception rates even more. Extending you
breeding season late into the summer to get extra cows bred is probably a futile exercise. Finally, genetics and other environmental factors play a role in infertility. Selection for other production traits can
sometimes lead to selection against reproductive ability. There are breed differences in reproductive efficiency,
especially when comparing Bos taurus to Bos indicus breeds. In general, Bos indicus breeds are superior in subtropical
climates, but have later puberty and longer intercalving interval than Bos Taurus breeds. There are wide variations
between individuals, so selecting for early maturity and shorter intercalving interval will increase efficiency over time.
Recent research has also focused on the influence of cow nutrition during gestation and its impact on subsequent
growth and fertility in their female offspring (“fetal programming”). Heifers born to cows that are deprived of protein
supplementation during late gestation, have lower average daily gains, delayed onset to puberty, and lower conception
rates compared to heifers born to protein supplemented cows. Even if heifers are fed properly once they are born,
nutrient deprivation in utero negatively impacts their future fertility.
Bulls should have a breeding soundness exam prior to each breeding season. Even if a bull passed last year, there is no
guarantee he will pass this year. Bull infertility due to heat stress is a major problem in LA. Although there are general

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