These disorders slow the reproductive tract repair processes and can lower conception rates, especially if they do not receive timely and effective treatment. It is important to note that all the problem cows in these herds were treated by the veterinarian. In spite of treatment, performance was still lower than that in normal cows. Thus, the key to maximizing conception rates must lie in the prevention of disorders, not treatment after they have occurred. Some evidence indicates cows suffering from metabolic disorders, like milk fever, may have a higher incidence of reproductive disorders and lower conception rates.
Cows are never in true estrus when progesterone is high.
Thus, when progesterone levels are high in milk samples obtained on the day of breeding, the cow is not in estrus. An estrous detection error has been made and the cow has no chance of conceiving since ovulation will not occur. The effect of estrous detection errors in a herd experiencing conception rate problems is illustrated in Table 2. Over 30 percent of the cows were not in estrus on the day they were bred. This obviously was the major cause of low conception rate.