Effects of first breeding age on the production and reproduction of Holstein heifers up to the third lactation |
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| Authors: | Minoru SAKAGUCHI Takahiro SUZUKI Yoshihiko SASAMOTO Yoshiyuki TAKAHASHI Akiko NISHIURA Mari AOKI |
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| Institution: | National Agricultural Research Center for Hokkaido Region, Toyohira-ku;and Graduate School of Veterinary Medicine, Hokkaido University, Kita-ku, Sapporo-shi, Japan |
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| Abstract: | The effects of early initiation of first service for dairy heifers on their fertility and productivity up to the third lactation were examined under constant raising and management conditions. Eight Holstein heifers in their early breeding regimens and eight Holstein heifers in their late breeding regimens were initiated to be bred at 12 and 15 months of age, respectively, and were first calved at 21.5 and 25.1 months of age, respectively, with bodyweights of 563 and 638 kg after calving, respectively. Early first breeding resulted in a lower bodyweight and a lower body condition score, but it did not affect the fertility or milk production during the first lactation of heifers as cows. The calving intervals of cows to the second and third calving were similar in early and late bred heifers. Although the early bred heifers had a significantly lower fat‐corrected milk yield at the second lactation than that of the late bred heifers, early breeding did not impair the productivity indicated by the mean milk yield per day from birth to the end of the third lactation with a shorter production period. |
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| Keywords: | body growth first-parity age Holstein heifer milk production reproduction |
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