Postpartum ovarian function and fertility in beef cattle that produce twins

A study was conducted to determine the effect of suckling on ovarian function and postpartum reproductive performance in beef cattle induced to produce twins by embryo transfer. This study involved 31 pluriparous Hereford, Angus and Hereford X Angus crossbred cows and 24 Hereford, Angus and Hereford X Angus crossbred heifers. Seventeen of the cows and 16 of the heifers calved twins, and the remainder produced single calves. From 45 d postpartum, the dams were exposed to three Hereford bulls until pregnancy was confirmed. The first postpartum ovulation was estimated from an increase in serum progesterone level. The interval to first postpartum ovulation was slightly, but not significantly longer for dams that calved and suckled twins than for dams that calved and suckled singles or calved twins and suckled singles (50.7 +/- 3.1, 43,5 +/- 3.4, and 37.7 +/- 5.6 d, respectively). This delay, however, did not significantly affect the number of days to conception for dams that suckled or calved twin or single calves. Once estrous cycles were initiated, the interval to conception for dams with twins was similar to that for dams with single calves. Under the management scheme used, postpartum ovulation and conception in beef heifers and cows were not significantly reduced by the production of twins.