University of Londrina (UEL), Laboratory of Animal Reproduction, Londrina, PR, Brazil.
University of Londrina (UEL), Laboratory of Animal Reproduction, Londrina, PR, Brazil.
Theriogenology. 2019 Sep 15;136:10-14. doi: 10.1016/j.theriogenology.2019.06.024. Epub 2019 Jun 17.
An experiment was performed to evaluate the association between the antral follicle count (AFC) plus body condition score (BCS) and the pregnancy rate in Bos indicus undergoing timed artificial insemination (TAI). A total of 736 Nelore cows with BCSs ranging from 2 to 4 received a conventional protocol for TAI. On a random day of the estrous cycle (Day 0), all cows received an intravaginal P4 device and an intramuscular (i.m.) injection of 2.0 mg estradiol benzoate. On Day 8, the P4 device was removed, and 150 μg sodium D-cloprostenol, 300 IU equine chorionic gonadotrophin and 1.0 mg estradiol cypionate were administered by i.m. injection. TAI was performed 48 h after P4 device removal, and pregnancy diagnosis was performed by ultrasonography after 30 days. On Day 0, all cows were examined by ultrasonography to determine the AFC by counting the number of follicles >3 mm in diameter that were present in both ovaries and to evaluate the BCS (scale of 1-5). The cows were then classified based on their AFCs as those with low (≤10 follicles), intermediate (11-29 follicles) and high AFC (≥30 follicles). Furthermore, cows were classified as having low (≥2.0 to ≤ 2.9) and high (≥3.0 to ≤ 4.0) BCSs. The AFCs and BCSs were analyzed using the generalized linear model, and the pregnancy rate was assessed with the binary logistic regression model (P ≤ 0.05). The pregnancy rate was influenced (P < 0.05) by AFC and BCS classification and by interactions (P = 0.034) between these factors. Cows with a low AFC exhibited higher a pregnancy rate than did cows with a high or an intermediate AFC (57.7% , 47.9% and 49.7% , P = 0.008). Low BCS resulted in a higher pregnancy rate than did high BCS (55.2% vs. 50.4%, P = 0.008). Cows with a high BCS and a low AFC had a higher pregnancy rate (P < 0.05) than did those with a high BCS and an intermediate or a high AFC (59.8%, 48.0%, and 38.0%, respectively). An interaction (P < 0.05) was observed between the AFC and BCS, and the pregnancy rate decreased significantly in cows with an AFC > 30 and a BCS between 3 and 4. In conclusion, AFC and BCS classifications influence the pregnancy rate of Bos indicus beef cattle subjected to TAI. In addition, an important interaction between these factors was observed, namely, the lowest pregnancy rates were found in cows with high BCSs and high AFCs.
进行了一项实验，以评估经定时人工授精（TAI）的印度野牛的窦卵泡计数（AFC）加体况评分（BCS）与妊娠率之间的关联。共有 736 头体况评分在 2 到 4 之间的尼洛牛接受了 TAI 的常规方案。在发情周期的任意一天（第 0 天），所有牛都接受了阴道内 P4 装置和 2.0mg 苯甲酸雌二醇的肌内（i.m.）注射。第 8 天，取出 P4 装置，并通过 i.m.注射给予 150μg 地诺前列酮钠、300IU 马绒毛膜促性腺激素和 1.0mg 环戊丙酸雌二醇。P4 装置取出后 48 小时进行 TAI，并在 30 天后通过超声检查进行妊娠诊断。第 0 天，所有牛都通过超声检查确定 AFC，方法是计数双侧卵巢中直径大于 3mm 的卵泡数量，并评估 BCS（1-5 级）。然后根据 AFC 将牛分为低（≤10 个卵泡）、中（11-29 个卵泡）和高（≥30 个卵泡）。此外，牛分为低（≥2.0 至≤2.9）和高（≥3.0 至≤4.0）BCS。使用广义线性模型分析 AFC 和 BCS，使用二元逻辑回归模型评估妊娠率（P≤0.05）。妊娠率受 AFC 和 BCS 分类以及这些因素之间的相互作用（P=0.034）的影响。低 AFC 的牛的妊娠率高于高 AFC 或中 AFC 的牛（57.7%、47.9%和 49.7%，P=0.008）。低 BCS 的牛的妊娠率高于高 BCS 的牛（55.2%比 50.4%，P=0.008）。高 BCS 和低 AFC 的牛的妊娠率高于高 BCS 和中 AFC 或高 AFC 的牛（59.8%、48.0%和 38.0%，分别）。观察到 AFC 和 BCS 之间存在交互作用（P<0.05），AFC>30 和 BCS 在 3 到 4 之间的牛的妊娠率显著下降。总之，AFC 和 BCS 分类会影响 TAI 后的印度野牛的妊娠率。此外，还观察到这些因素之间存在重要的相互作用，即高 BCS 和高 AFC 的牛的妊娠率最低。
