Effects of Early Weaning on Postpartum Reproduction of the Dam and Growth of Calves Born as Multiples or Singles

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Abstract
Two studies were conducted to produce multiple births in beef females and determine growth performance to 90 days of age of early weaned and artificially reared calves. The effects of early weaning on postpartum reproductive activity of dams producing single or multiple births were also determined. The studies involved 52 nulliparous heifers treated with 6.2 mg FSH and 55 lactating 2-year-old dams treated with either 6.2 or 9.4 mg FSH. Estrus was synchronized with MAP and estradiol. Calves were removed from their dams at 3, 10, 35 or 90 days of age. Calves weaned before 35 days were fed cold (1.7 to 2.8 C) whole milk or cold milk replacer ad libitum to 35 days of age. Net calf production from dams in the superovulated groups ranged from 71 to 111%. Gestation lengths of single calves were longer (P< .01) than those of multiples and incidence of retained placenta increased in dams producing multiple births. Weaning calves early resulted in a shortening (P< .01) of the postpartum interval to first estrus, regardless of type of birth. Weight gains of early weaned calves were normal and digestive problems were minimal. Copyright © 1974. American Society of Animal Science . Copyright 1974 by American Society of Animal Science.