Flores R, Looper M L, Kreider D L, Post N M, Rosenkrans C F
Department of Animal Science, University of Arkansas, Fayetteville 72701, USA.
J Anim Sci. 2006 Jul;84(7):1916-25. doi: 10.2527/jas.2005-692.
Spring-calving, crossbred (1/4 to 3/8 Brahman) primiparous (n = 56) and multiparous (n = 102) beef cows were used to evaluate the effects of progesterone, delivered via a controlled internal drug-releasing (CIDR) device, and prostaglandin F(2alpha) (PGF(2alpha)) on estrous behavior, synchronization rate, initiation of estrous cycles, and pregnancy rate during a 2-yr period. To determine luteal activity, weekly blood samples were collected 3 wk before initiation of a 75-d breeding season. Treated cows received a CIDR for 7 d beginning on d -7 of the breeding season. On d 0, CIDR were removed, and cows receiving CIDR were administered PGF(2alpha); control cows received no treatment. Cows were exposed to bulls, and estrous activity was monitored using a radiotelemetry system for the first 30 d of the breeding season. Treatment with CIDR-PGF(2alpha) increased (P < 0.05) the number of mounts received (22.5 +/- 3.0 vs. 13.7 +/- 3.9 for CIDR-PGF(2alpha) vs. untreated control cows, respectively) but did not influence duration of estrus or quiescence between mounts. Number of mounts received and duration of estrus were greater (P < 0.05) in multiparous compared with primiparous cows. Synchronization of estrus was greater (P < 0.05) in cows treated with CIDR-PGF(2alpha) (56%) compared with control cows (13%) during the first 3 d of the breeding season. More (P < 0.05) anestrous cows treated with CIDR-PGF(2alpha) than anestrous control cows were in estrus during the first 3 d (59 vs. 12%) and 30 d (82 vs. 63%) of the breeding season. Treatment with CIDR-PGF(2alpha) decreased (P < 0.05) the interval to first estrus after treatment during the first 30 d of the breeding season compared with control cows (5.5 +/- 1.1 vs. 9.0 +/- 1.4 d). First service conception rate was greater (P < 0.05) in CIDR-PGF(2alpha)-treated cows compared with control cows. Cyclic cows at initiation of the breeding season had an increased (P < 0.05) 75-d pregnancy rate compared with anestrous cows, and the pregnancy rate tended (P = 0.10) to be greater in multiparous compared with primiparous cows. We conclude that treatment of Brahman-influenced cows with progesterone via a CIDR for 7 d, along with administration of PGF(2alpha) at CIDR removal, increases the number of mounts received, improves synchronization and first service conception rates, decreases the interval to first estrus after treatment, and may be effective at inducing estrous cycles in anestrous cows.
在为期两年的时间里，使用春季产犊、杂交（含1/4至3/8婆罗门牛血统）的初产母牛（n = 56头）和经产母牛（n = 102头）来评估通过控制内部药物释放（CIDR）装置给予的孕酮和前列腺素F2α（PGF2α）对发情行为、同步率、发情周期起始以及妊娠率的影响。为确定黄体活性，在75天繁殖季节开始前3周每周采集血样。处理组母牛在繁殖季节第 -7天开始接受CIDR处理7天。在第0天，取出CIDR，接受CIDR处理的母牛注射PGF2α；对照组母牛不做处理。母牛与公牛接触，并在繁殖季节的前30天使用无线电遥测系统监测发情活动。CIDR - PGF2α处理使接受爬跨的次数增加（P < 0.05）（分别为22.5 ± 3.0次和13.7 ± 3.9次，CIDR - PGF2α处理组与未处理的对照组母牛相比），但不影响发情持续时间或两次爬跨之间的静止期。经产母牛接受爬跨的次数和发情持续时间比初产母牛更多（P < 0.05）。在繁殖季节的前3天，接受CIDR - PGF2α处理的母牛（56%）发情同步率比对照组母牛（13%）更高（P < 0.05）。在繁殖季节的前3天（59%对12%）和30天（82%对63%），接受CIDR - PGF2α处理的乏情母牛比乏情对照组母牛发情的更多（P < 0.05）。与对照组母牛相比，在繁殖季节的前30天，CIDR - PGF2α处理使处理后至首次发情的间隔缩短（P < 0.05）（分别为5.5 ± 1.1天和9.0 ± 1.4天）。与对照组母牛相比，接受CIDR - PGF2α处理的母牛首次输精受胎率更高（P < 0.05）。繁殖季节开始时的经产母牛75天妊娠率比乏情母牛有所增加（P < 0.05），经产母牛的妊娠率与初产母牛相比有升高趋势（P = 0.10）。我们得出结论，对受婆罗门牛影响的母牛使用CIDR给予孕酮7天，并在取出CIDR时注射PGF2α，可增加接受爬跨的次数，提高同步率和首次输精受胎率，缩短处理后至首次发情的间隔，并且可能对诱导乏情母牛发情周期有效。
