Clitoral stimulation after artificial insemination (AI) in beef cattle is a common practice utilized by AI technicians; however, the effect of clitoral stimulation during fixed-time AI (TAI) is still unknown. The objective of the present experiment was to evaluate the effect of clitoral stimulation on temperament responses and pregnancy rates to TAI in Bos indicus beef cows. A total of 1,186 multiparous Nellore cows across three different locations were assigned to an estradiol/progesterone-based estrus synchronization + TAI protocol (day −11 to 0). Cows were randomly assigned to receive either 3 s of clitoral stimulation (n = 602) or no clitoral stimulation (n = 584) immediately after TAI (day 0). Cow body condition score (BCS) was recorded on day −11. Estrus expression was evaluated based on estrus detection visual aid patch activation on day 0 (estrus, ≥50% activated; no estrus, <50% activated). Temperament was assessed by individual chute score based on a 5-point scale before TAI, and individual exit velocity was measured after clitoral stimulation. Pregnancy diagnosis was performed 30 d after TAI via transrectal ultrasonography. Pregnancy rate to TAI was positively affected by BCS (P < 0.01) and estrus expression (P = 0.03). Pregnancy rates of cows receiving clitoral stimulation did not differ (P = 0.39) from cows non-stimulated (47.5 ± 4.6% vs. 44.3 ± 4.6%, respectively). No interaction of clitoral stimulation and estrus expression was observed (P = 0.26). Chute score was positively correlated to exit velocity (P < 0.01; r = 0.29); however, clitoral stimulation did not affect exit velocity (P = 0.86). In summary, pregnancy rates to TAI are influenced by various factors and multiple strategies have the potential to increase the fertility of beef cows submitted to TAI; however, clitoral stimulation of Bos indicus beef cows did not improve TAI pregnancy rate.

中文翻译：

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人工授精后阴蒂刺激对提交雌二醇/孕酮发情同步方案的多头印度ous牛的怀孕率的影响。

人工授精（AI）后肉牛的阴蒂刺激是AI技术人员常用的做法；然而，在固定时间AI（TAI）期间阴蒂刺激的效果仍然未知。本实验的目的是评估阴蒂刺激对印度乳牛（Bos indicus）牛的气质响应和TAI妊娠率的影响。将在三个不同位置的总计1,186头内罗尔牛产于基于雌二醇/孕酮的发情同步+ TAI协议（第-11天到第0天）。母牛被随机分配为接受3 s的阴蒂刺激（n = 602）或不接受阴蒂刺激（n= 584）紧接在TAI之后（第0天）。在第-11天记录母牛的身体状况评分（BCS）。根据第0天发情检测视觉辅助贴片的激活（发情，≥50％；未发情，<50％）评估发情表达。在TAI之前通过基于5点量表的个人滑道得分来评估气质，并且在阴蒂刺激之后测量个体出口速度。TAI后30 d通过经直肠超声检查进行妊娠诊断。TAI的怀孕率受到BCS（P < 0.01）和发情表达（P = 0.03）的正影响。受到阴蒂刺激的母牛的妊娠率没有差异（P= 0.39）来自未受刺激的母牛（分别为47.5±4.6％和44.3±4.6％）。没有观察到阴蒂刺激和发情表达的相互作用（P = 0.26）。溜槽得分与出口速度呈正相关（P <0.01；r = 0.29）；然而，阴蒂刺激并不影响出口速度（P = 0.86）。总而言之，TAI的怀孕率受多种因素的影响，多种策略有可能增加提交TAI的肉牛的生育能力。然而，阴蒂刺激Bos indicus肉牛并不能提高TAI怀孕率。