Infectious Diseases that Affect Cattle Fertility
Nolan R. Hartwig, DVM, Iowa State University
Calving percentage, the number of calves weaned divided by the number of females exposed to bulls the previous year, is the most important production parameter that can be measured. The first priority of cow/calf health and production programs should be to emphasize reproduction.
The most common cause of reproductive failure in beef herds is failure to conceive in the first place. Failure of cows and heifers to come in estrus while exposed to bulls is the leading cause of conception failure. The most common cause of anestrus, in turn, is nutrition; specifically lack of energy intake during the early lactation period. Body condition and energy intake pre- and post-calving are critical aspects of maintaining high herd fertility. A basic health program should include condition scoring cows in late fall and feeding accordingly through the post calving period. Infectious diseases are often immediately blamed when unacceptably high numbers of open cows and heifers are encountered. Cow condition and nutrition should be the first consideration. Protein deficiency is uncommon as a cause of infertility. Minerals such as phosphorus, selenium, copper, zinc, and others should be considered, but can usually be handled when mineral and salt mixtures designed for beef cows are available in a palatable form. Toxins such as endophyte infected fescue should also be considered when infertility problems occur
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