Previous pregnancy carry-over effects on the folliculogenesis in the postpartum cows ovaries
1995
Kamimura, S. (Kagoshima Univ. (Japan). Faculty of Agriculture) | Mizushima, Y. | Nagano, M. | Hamana, K.
64 Holstein cows and 10 Japanese black cows were subjected for examining the carry-over effects of previous pregnancy on the the postpartum folliculogenesis. A series of monitoring by ultrasonography, beginning on the 6th and ending at the first ovulation were carried out twice a week, and the following results were obtained. concerning the locations of gravid horn (left and right uterine horns, respectively) at the previous pregnancy, no considerable difference was noted between the two, namely, in the individuals of 36 cows the location was noted at the left uterine horns and in those of 38 cows, at the right uterine horns, respectively. On the other hand, as to the emergence of first dominant follicle (DF = 10 mm in diameter) and ovulations, significant observations of both of which were made in the non-gravid ovaries rather than in the post-gravid ones (DF detection ratios: 61/74 versus 13/74, ovulation: 36/61 versus 3/13, both in P 0.01 level). As to the relationship between the number of calvings and ovulation of the first DF, ovulation rate was apt to be decreasing in cows which had undergone more than 5 times of calvings, compared with those less than 4 times of calvings. Follicular profiles determined in the ovarian map designed by serial ovarian dissections indicated that folliculogenesis was apt to be suppressed in cows with abnormal pregnancy. Suppressive carry-over effects of the previous pregnancy upon the postpartum folliculogenesis and ovulation were obviously observed in the post-gravid ovaries
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