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KMID : 0900919980220040341
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Korean journal of Animal Reproduction
1998 Volume.22 No. 4 p.341 ~ p.347
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Change of Serum Progesterone and Insulin-like Growth Factor-1 Concentration during the First Oestrus in the Heifers of Hanwoo
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Ko Yeoung-Gyu
Seong Hwan-Hoo
Baek Kwang-Soo
Na S. H.
Choe C.-Y.
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Abstract
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This study was conducted to determine changes in circulating progesterone and Insulin-like Growth Factor-1(IGF-1) concentrations according to daily gain of 0.5 and 0.7 kg ; from 33 weeks of age until the onset of regular oestrus cycles in the heifer of Hanwoo. In all animals, progesterone concentrations was undetectable until just before first oestrus. A small progesterone elevation of approximately 6 days duration(based upon the mean progesterone profile) preceded the first oestrus in 13 heifers. The mean age at first oestrus of the daily gain 0.7 kg(331.0pm 15.0 days) group was earlier than those of the daily gain 0.5 kg(358.9pm7.9 days) group, and the mean weight at first oestrus of the daily gain 0.7 kg(236.0pm4.7 kg) group was heavier than those of the daily gain 0.5 kg(224.8pm9.7 kg) group. IGF-1 concentrations from day 3 to 15 of first oestrus were higher than those of the earlier luteal stage(Day 0~1) and the luteal regression stage (Day 18~20). IGF-1 concentrations according to the growth stage (from 33 weeks to 57 weeks) increased gradually. On the basis of these results, we suggest that the onset of first oestrus in Hanwoo heifer is about 345 day of age, and progesterone concentrations are closely related to the IGF-1 concentration.
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KEYWORD
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First oestrus, Hanwoo, Heifers, Progesterone, Insuline-like Growth Factor-1
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