Our objective was to determine if the addition of a concentrated human recombinant transforming growth factor beta-1 (TGF) to bovine semen at the time of AI would result in increased risk of pregnancy in beef and dairy cows. Suckled beef cows (n = 1,132) in 11 herds across 2 states and lactating dairy cows (n = 2,208) in one organic-certified herd were enrolled. Beef cows received fixed-time AI (FTAI) following a 7 d CO-Synch + controlled internal drug release estrous synchronization protocol. Dairy cows were inseminated following observation of natural estrus expression. Cows received either no treatment as a control (CON) or 10 ng of TGF in 10 μl added through the cut-end of a thawed straw of semen immediately prior to AI. At the time of FTAI of beef cows, the mean ± SD age was 5.0 ± 2.4 yr, BCS was 5.3 ± 0.7, and days postpartum was 78.2 ± 15.5 d. The overall pregnancy risk in beef cows was 55.2% to AI and 90.5% season-long. Pregnancy risk in beef cows was not affected (P = 0.27) by addition of TGF (53.1% vs. 58.1%). Further, there was no difference (P = 0.88) for season-long pregnancy risk in beef cows that received TGF (91.2% vs. 91.5%). At the time of insemination of dairy cows, the mean ± SD lactation was 3.0 ± 1.3 lactations, BCS was 2.9 ± 0.3, days in milk was 115.6 ± 56.6 d, and cows had received 2.4 ± 1.5 inseminations per cow. The overall pregnancy risk to AI in dairy cows was 23.1%. Pregnancy risk to AI for dairy cows was not affected (P = 0.32) by addition of TGF (22.0% vs. 23.8%). In conclusion, pregnancy risk to AI was not affected by addition of TGF to thawed semen immediately prior to AI in beef or dairy cows.

中文翻译：

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人工授精时补充转化生长因子β-1精液后肉牛和奶牛的怀孕风险


我们的目标是确定在人工授精时向牛精液中添加浓缩的人类重组转化生长因子β-1 (TGF) 是否会导致肉牛和奶牛怀孕的风险增加。纳入了 2 个州 11 个牛群中的哺乳肉牛 (n = 1,132) 和一个有机认证牛群中的泌乳奶牛 (n = 2,208)。肉牛按照 7 天 CO-Synch + 受控内部药物释放发情同步方案接受固定时间 AI (FTAI)。在观察自然发情表达后对奶牛进行授精。奶牛要么不接受任何治疗作为对照 (CON)，要么在 AI 前立即通过解冻精液吸管的切口添加 10 μl 中的 10 ng TGF。肉牛 FTAI 时，平均±SD 年龄为 5.0±2.4 岁，BCS 为 5.3±0.7，产后天数为 78.2±15.5 天。肉牛的 AI 总体妊娠风险为 55.2%，整个季节的妊娠风险为 90.5%。添加 TGF 不会影响肉牛的妊娠风险（P = 0.27）（53.1% vs. 58.1%）。此外，接受 TGF 的肉牛整个季节的妊娠风险没有差异（P = 0.88）（91.2% 与 91.5%）。奶牛授精时，平均±SD泌乳量为3.0±1.3次泌乳，BCS为2.9±0.3，产奶天数为115.6±56.6天，每头奶牛接受了2.4±1.5次授精。奶牛感染 AI 的总体妊娠风险为 23.1%。添加 TGF 不会影响奶牛 AI 的妊娠风险（P = 0.32）（22.0% 与 23.8%）。总之，在牛肉或奶牛发生 AI 之前向解冻精液中添加 TGF 不会影响 AI 妊娠风险。