Effect of Monensin Supplementation on Follicular Development of Brahman Cows and the Effect of Sex and Temperament on Response of Beef Calves to Salmonella Newport Extract Vaccine

Abstract

Beef production relies on the intricacies of the reproductive and immune systems of cattle. These physiological systems are especially important to the management of mature cows and their calves in cow-calf operations. The physiological processes studied included 1) the effect of monensin supplementation on postpartum folliculogenesis in mature Brahman cows and 2) the effect of sex and temperament on adaptive immune function of beef calves. The return to normal ovarian function following calving is dependent on populations of follicles during the early postpartum period; this was evaluated in mature Brahman cows 21 d following calving. Monensin supplementation provided to Brahman cows from late gestation until early lactation increased recruitment of antral follicles. Additionally, neither cow nor calf BW were affected by monensin supplementation. Because immune and stress responses are sexually dimorphic and vary amongst temperaments two experiments were conducted to determine the effects of sex and temperament on response to Salmonella Newport Extract vaccine at weaning in Bos taurus and Bos indicus beef calves. There was a sexually dimorphic immune response both in Bos taurus and Bos indicus calves as well as a significant influence of temperament on immune response in Bos indicus calves. However, the degree of immune response appeared to be adequate to confer immunity after the booster vaccination. The findings of these experiments are applicable to the management of the reproductive and immune systems of cattle thus benefiting beef cattle production.