Lemaster J W, Yelich J V, Kempfer J R, Schrick F N
Department of Animal Sciences, University of Florida, Gainesville 32611-0910, USA.
J Anim Sci. 1999 Jul;77(7):1860-8. doi: 10.2527/1999.7771860x.
Crossbred Brahman heifers (n = 60) were studied to determine the effect of a 7-d intravaginal progesterone-releasing insert (INSERT) in combination with PG (Lutalyse; 25 mg i.m.) and estradiol benzoate (EB; .5 mg i.m.) on time of ovulation and estrous behavior. In Phase I, heifers at unknown stages of the estrous cycle were assigned by BW and body condition score to one of the three treatments on d 0: 1) INSERT for 7 d and PG on d 7 (CONTROL; n = 10); 2) INSERT for 7 d, PG on d 7, and EB 24 h after INSERT removal (EB24; n = 10); or 3) INSERT for 7 d, PG on d 7, and EB 48 h after INSERT removal (EB48; n = 10). Blood samples were collected every 8 h after INSERT removal. Also, blood sampling and ultrasonography began 8 h after the onset of estrus, determined with HeatWatch devices, and every 4 h thereafter to detect ovulation. In Phase II, Phase-I treatments (n = 10/treatments) were replicated, but only behavioral estrus data were collected to minimize handling of heifers. Frequent handling of heifers did not influence (P > .1) the interval from INSERT removal to the onset of HeatWatch and visual estrus and duration of estrus, so behavioral estrus data were combined for Phases I and II. Interval from INSERT removal to HeatWatch estrus was decreased (P < .05) in EB24 (45.5 h) vs EB48 (55.9 h) and CONTROL (59.2 h). Interval from INSERT removal to ovulation differed (P < .04) between CONTROL, EB24, and EB48 (93.5, 74.5, and 78.9 h, respectively). Ovulatory follicle size was similar (P > .1) between CONTROL, EB24, and EB48 (14.4, 12.5, and 14.1 mm, respectively). Duration of estrus was similar for CONTROL, EB24, and EB48 (14.0, 15.1, and 17.6 h, respectively). No difference (P > . 1) was observed in number of mounts received between CONTROL, EB24, and EB48 (28.0, 25.7, and 39.4, respectively), but number of mounts received increased in Phase II vs Phase I (40.0 and 22.2, respectively; P < .05). In conclusion, EB hastened the interval from INSERT removal to ovulation without altering duration of estrus or number of mounts received. Frequent handling of heifers did not affect interval to first mount received after INSERT removal or duration of estrus, but it decreased the total number of mounts received.
对60头杂交婆罗门小母牛进行了研究，以确定7天的阴道内释放孕酮植入物（INSERT）与氯前列醇（Lutalyse；25毫克肌肉注射）和苯甲酸雌二醇（EB；0.5毫克肌肉注射）联合使用对排卵时间和发情行为的影响。在第一阶段，处于发情周期未知阶段的小母牛在第0天根据体重和体况评分被分配到三种处理之一：1）INSERT处理7天，并在第7天注射PG（对照；n = 10）；2）INSERT处理7天，第7天注射PG，并在取出INSERT后24小时注射EB（EB24；n = 10）；或3）INSERT处理7天，第7天注射PG，并在取出INSERT后48小时注射EB（EB48；n = 10）。取出INSERT后每8小时采集一次血样。此外，在通过HeatWatch设备确定发情开始后8小时开始采血和超声检查，并在此后每4小时进行一次，以检测排卵。在第二阶段，重复第一阶段的处理（每个处理n = 10），但仅收集行为发情数据，以尽量减少对小母牛的处理。频繁处理小母牛对从取出INSERT到HeatWatch发情开始的间隔以及发情持续时间没有影响（P > 0.1），因此将第一阶段和第二阶段的行为发情数据合并。与EB48（55.9小时）和对照（59.2小时）相比，EB24组（45.5小时）从取出INSERT到HeatWatch发情的间隔缩短（P < 0.05）。对照、EB24和EB48组从取出INSERT到排卵的间隔不同（P < 0.04）（分别为93.5、74.5和78.9小时）。对照、EB24和EB48组排卵卵泡大小相似（P > 0.1）（分别为14.4、12.5和14.1毫米）。对照、EB24和EB48组的发情持续时间相似（分别为14.0、15.1和17.6小时）。对照、EB24和EB48组接受爬跨的次数没有差异（P > 0.1）（分别为28.0、25.7和39.4次），但第二阶段接受爬跨的次数比第一阶段增加（分别为40.0和22.2次；P < 0.05）。总之，EB缩短了从取出INSERT到排卵的间隔，而不改变发情持续时间或接受爬跨的次数。频繁处理小母牛不影响取出INSERT后到首次接受爬跨的间隔或发情持续时间，但会减少接受爬跨的总次数。
