Savio J D, Boland M P, Hynes N, Roche J F
Faculty of Veterinary Medicine, University College Dublin, Ireland.
J Reprod Fertil. 1990 Mar;88(2):569-79. doi: 10.1530/jrf.0.0880569.
Lactating Friesian dairy cows (2nd-4th parity) which calved in spring (N = 7) or autumn (N = 15) were used. Their ovaries were examined by ultrasound scanning and blood samples were obtained daily for progesterone and oestradiol concentrations from the 5th day after calving until the first post-partum ovulation occurred. Five autumn-calving cows selected at random were bled every 15 min over a 6-h period on 1 day each week for 4 weeks after calving to assess the patterns of LH secretion. Follicular development during the post-partum anoestrous period was characterized by the growth and regression of small (less than or equal to 4 mm) and medium-sized (5-9 mm) follicles, until a dominant follicle (greater than 10 mm) was detected. The first detected dominant follicle ovulated in 14 cows, became cystic in 4 cows (all in autumn), and failed to ovulate in 1 cow. It was not possible to detect a dominant follicle in 3 cows due to scanning difficulties. The post-partum interval to detection of the first dominant follicle (mean +/- s.d.) was shorter (P less than 0.05) in autumn (6.8 +/- 1.8 days) than in spring (20 +/- 10.1 days). However, there was no significant difference between the respective intervals to first ovulation (autumn 27.4 +/- 25.9 and spring 27.3 +/- 18.9 days). Autumn-calved cows which had cysts had longer (P less than 0.001) intervals to first ovulation (58.2 +/- 23.5 days) than did normal cows (12.0 +/- 2.5 days). All cows with cysts had twin ovulations at their first post-partum ovulation. A pulsatile pattern of LH secretion was detected in the first week post-partum and LH pulse frequency was 2-3 per 6-h period in Weeks 1 and 2 post partum and increased to 5-7 pulses per 6-h period in the presence of a dominant or cystic follicle. Concentrations of progesterone in plasma during post-partum anoestrus were usually low (less than 0.2 ng/ml); oestradiol concentrations were also low (less than 5 pg/ml), but higher values (5-110 pg/ml) were observed in cows that had a dominant or a cystic follicle.
选用了在春季产犊的7头和秋季产犊的15头处于第2至第4胎次的泌乳弗里生奶牛。从产犊后第5天直至产后首次排卵，通过超声扫描检查其卵巢，并每天采集血样检测孕酮和雌二醇浓度。随机选择5头秋季产犊的奶牛，在产后4周内，每周1天，在6小时内每隔15分钟采血一次，以评估促黄体生成素（LH）的分泌模式。产后乏情期的卵泡发育特征为小卵泡（直径小于或等于4毫米）和中等大小卵泡（直径5至9毫米）的生长与退化，直至检测到优势卵泡（直径大于10毫米）。首次检测到的优势卵泡在14头奶牛中排卵，在4头奶牛中形成囊肿（均为秋季产犊），在1头奶牛中未排卵。由于扫描困难，在3头奶牛中未检测到优势卵泡。产后至首次检测到优势卵泡的间隔时间（均值±标准差）在秋季（6.8±1.8天）比春季（20±10.1天）短（P<0.05）。然而，至首次排卵的各自间隔时间之间无显著差异（秋季27.4±25.9天，春季27.3±18.9天）。有囊肿的秋季产犊奶牛至首次排卵的间隔时间（58.2±23.5天）比正常奶牛（12.0±2.5天）长（P<0.001）。所有有囊肿的奶牛在产后首次排卵时都出现双排卵。在产后第一周检测到LH分泌呈脉冲式模式，产后第1周和第2周LH脉冲频率为每6小时2至3次，在出现优势卵泡或囊肿性卵泡时增加到每6小时5至7次。产后乏情期血浆中的孕酮浓度通常较低（低于0.2纳克/毫升）；雌二醇浓度也较低（低于5皮克/毫升），但在有优势卵泡或囊肿性卵泡的奶牛中观察到较高值（5至110皮克/毫升）。
