The following is a list of factors that can contribute to a higher than usual rate of infection. Overconditioning at the time of calving has been related to a higher incidence of infections in some studies but not in others. However, it makes some sense that overconditioned cows might have poorer uterine muscle tone, fatigue earlier during the calving process, experience a higher incidence of difficult births and thus have a higher incidence of uterine infections than cows in good body condition. On the other hand, severely underconditioned cows appear to be more susceptible to infection than cows in proper condition. It is important to maintain adequate levels of calcium, selenium, vitamin A and E in the rations of both dry and lactating cows.
Calcium is important for proper uterine smooth muscle contraction.
Low levels of blood calcium may contribute to retained placenta which generally results in uterine infection and low calcium may also delay uterine involution. Selenium has also been shown to be involved in uterine contraction. Selenium and vitamin E supplementation have frequently been shown to reduce the incidence of retained placenta in herds where the levels of these nutrients were low. Vitamin A is important to maintaining and repairing epithelial tissues which line the interior of organs. With respect to reproduction, vitamin A is probably important to uterine involution and maintenance of healthy uterine tissue.