Floyd L N, Lents C A, White F J, Wettemann R P
Department of Animal Science, Oklahoma Agricultural Experiment Stations, Stillwater 74078-0425, USA.
J Anim Sci. 2009 Jun;87(6):1998-2004. doi: 10.2527/jas.2008-1380. Epub 2009 Feb 27.
Mature Angus and Angus x Hereford cows were used to determine the effects of confinement area and number of cows in estrus on estrous behavior. During each of 2 replicates, 32 nonpregnant, nonlactating cows were maintained in a drylot (60 x 100 m) or in a pasture (12 ha). Estrous cycles were synchronized with 2 injections of PGF(2alpha) 10 to 14 d apart at the initiation of the experiment. Thereafter, PGF(2alpha) was administered between d 6 and 18 of the estrous cycle so that 1, 2 to 3, 4 to 6, or > or = 7 cows were in estrus at the same time. Concentrations of progesterone were quantified in plasma at treatment to ensure cows had a normal response to PGF(2alpha). Duration of estrus and the number of mounts received during estrus were recorded by HeatWatch. If any part of estrus for a cow occurred at the same time as estrus for another cow, the cow was considered to have concurrent estrus with the other cow. Cows in the drylot had a shorter (P < 0.02; 61.8 +/- 3.1 h) interval to estrus after PGF(2alpha) compared with cows on pasture (72.8 +/- 3.3 h). The interval to estrus was longer (P < 0.07) when cows were treated with PGF(2alpha) on d 10 to 13 (76.7 +/- 3.3 h) of the estrous cycle than when treated on d 6 to 9 (62.3 +/- 4.7 h) or d 14 to 18 (62.9 +/- 3.6 h). Increasing the number of cows concurrently in estrus increased the number of mounts each cow received per estrus (P < 0.001) and the duration of estrus (P < 0.01). When only 1 cow was in estrus, she received 11.0 +/- 6.2 mounts during 11.6 +/- 1.5 h. When > or = 7 cows were in estrus at the same time, each cow received 50.4 +/- 3.2 mounts during 17.3 +/- 0.8 h. Cows in drylot were in estrus longer (P < 0.04; 16.4 +/- 0.8 h) than cows on pasture (14.2 +/- 0.7 h). Duration of the longest interval between mounts received decreased (P < 0.002) as the number of cows in estrus at one time increased (5.3 +/- 0.7 h for 1 estrous cow; 2.6 +/- 0.3 h when > or = 7 cows were in estrus). We conclude that increasing the number of beef cows in estrus at the same time will increase the number of times a cow is mounted and the duration of estrus. The increase in estrous behavior associated with more cows in estrus could increase the number of estrous cows detected with infrequent visual observation.
选用成年安格斯牛以及安格斯×赫里福德杂交母牛，以确定圈养面积和发情母牛数量对发情行为的影响。在2次重复试验的每次试验期间，将32头未怀孕、未泌乳的母牛饲养在一个干栏（60×100米）或一片牧场（12公顷）中。在试验开始时，每隔10至14天注射2次PGF（2α）使发情周期同步。此后，在发情周期的第6至18天给予PGF（2α），以便使1头、2至3头、4至6头或≥7头母牛同时发情。在处理时测定血浆中孕酮的浓度，以确保母牛对PGF（2α）有正常反应。发情持续时间以及发情期间接受爬跨的次数由HeatWatch记录。如果一头母牛发情的任何时间段与另一头母牛的发情期同时出现，则该母牛被认为与另一头母牛同时发情。与在牧场的母牛相比，干栏中的母牛在注射PGF（2α）后至发情的间隔时间更短（P<0.02；61.8±3.1小时），而牧场中的母牛为（72.8±3.3小时）。在发情周期的第10至13天（76.7±3.3小时）用PGF（2α）处理母牛时，至发情的间隔时间比在第6至9天（62.3±4.7小时）或第14至18天（62.9±3.6小时）处理时更长（P<0.07）。同时发情的母牛数量增加，每头母牛每次发情接受爬跨的次数（P<0.001）以及发情持续时间（P<0.01）都会增加。当只有1头母牛发情时，它在11.6±1.5小时内接受11.0±6.2次爬跨。当≥7头母牛同时发情时，每头母牛在17.3±0.8小时内接受50.4±3.2次爬跨。干栏中的母牛发情持续时间比牧场中的母牛更长（P<0.04；16.4±0.8小时），而牧场中的母牛为（14.2±0.7小时）。随着同时发情的母牛数量增加，接受爬跨的最长间隔时间缩短（P<0.002）（1头发情母牛为5.3±0.7小时；≥7头发情母牛时为2.6±0.3小时）。我们得出结论，同时发情的肉牛数量增加会增加母牛被爬跨的次数以及发情持续时间。与更多发情母牛相关的发情行为增加可能会增加在不频繁目视观察情况下检测出发情母牛的数量。
