Influence of Suckling Intensity on Reproductive Performance of Range Cows

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Abstract
Forty-four Hereford × Holstein cows were assigned at calving to one of three suckling intensities; one natural calf, one foster calf or two calves. The cows were maintained under range conditions and supplemental concentrates were fed so body weight loss during lactation was similar for all cows. Sterile bulls were used to aid in the detection of estrus. Blood plasma samples were obtained once weekly after parturition until about 85 days postpartum and progesterone was quantified by radioimmunoassay. The first postpartum estrus (P<.05) and ovulation (P<.005) occurred earlier in cows suckling one calf (natural or foster) than in cows suckling two calves. Estrus had occurred by 90 days postpartum in 71.4% of the cows with their own calves, 88.8% of the cows with one foster calf and only 42.8% (P<.05) of the cows suckling two calves. It was concluded that increasing the suckling intensity increased the postpartum anestrous interval in range cows although the percentage body weight loss during lactation was maintained constant for all suckling intensities. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.