Ferraz Junior Marcos V C, Pires Alexandre V, Biehl Marcos V, Santos Marcelo H, Barroso José P R, Gonçalves José R S, Sartori Roberto, Day Michael L
Department of Nutrition and Animal Production, Faculty of Veterinary and Animal Science, University of São Paulo, São Paulo, Brazil.
Department of Nutrition and Animal Production, Faculty of Veterinary and Animal Science, University of São Paulo, São Paulo, Brazil; Department of Animal Science, College of Agriculture "Luiz de Queiroz" (ESALQ), University of São Paulo, São Paulo, Brazil.
Theriogenology. 2016 Nov;86(8):1939-43. doi: 10.1016/j.theriogenology.2016.06.012. Epub 2016 Jun 23.
The aim of this study was to evaluate the reproductive performance of 411 Nellore cows (198 nulliparous, 80 primiparous, and 133 multiparous) submitted to the 5dCO-Synch + P4 or 7dEB + P4 systems. The 5dCO-Synch + P4 system consisted of insertion of an intravaginal progesterone (P4) insert and 100 μg of GnRH (intramuscularly [i.m.]) on Day 0. On Day 5, the P4 insert was removed, and two doses of 25 mg of PGF2α (i.m.) were administered 6 hours apart. Cows not detected in estrus until 55 hours after insert removal received 100 μg of GnRH i.m. 17 hours later (i.e., 72 hours after P4 removal). The 7dEB + P4 system consisted of insertion of a P4 insert and 2 mg of estradiol benzoate (i.m.) on Day 0. On Day 7, the P4 insert was removed and 25 mg of PGF2α, 0.6 mg of estradiol cypionate, and 300 IU of eCG were administered i.m. In both systems, artificial insemination (AI) was performed according to estrus detection (i.e., cows detected in estrus until 55 hours after insert removal were inseminated at 55 hours and cows detected in estrus later or those not detected in estrus were inseminated at 72 hours). Estrus-detection risk was greater (P < 0.05) in 7dEB + P4 (80.4%) than 5dCO-Synch + P4 system (36.4%). Progesterone concentration 10 days after AI was greater (P < 0.05) in 7dEB + P4 than 5dCO-Synch + P4 system in primiparous and multiparous but did not differ between systems in nulliparous cows. Pregnancy per AI was greater (P < 0.05) in 7dEB + P4 (49.7%) than 5dCO-Synch + P4 (35.4%) system. Primiparous had lower estrus-detection risk (25.0%), ovulation risk (76.6%), and pregnancy per AI (28.7%) than multiparous or nulliparous cows. In conclusion, reproductive performance was reduced with the 5dCO-Synch + P4 in comparison with the 7dEB + P4 system in Nellore cows. Moreover, the reproductive traits observed for primiparous cows indicate that more attention is required when timed AI programs are started early after calving.
本研究的目的是评估411头内洛尔牛（198头未产牛、80头初产牛和133头经产牛）采用5dCO-Synch + P4或7dEB + P4方案后的繁殖性能。5dCO-Synch + P4方案包括在第0天插入阴道孕酮（P4）植入物并肌注100 μg促性腺激素释放激素（GnRH）。在第5天，取出P4植入物，并间隔6小时肌注两剂25 mg的前列腺素F2α（PGF2α）。在取出植入物后55小时仍未检测到发情的母牛，17小时后（即取出P4后72小时）肌注100 μg GnRH。7dEB + P4方案包括在第0天插入P4植入物并肌注2 mg苯甲酸雌二醇。在第7天，取出P4植入物，并肌注25 mg PGF2α、0.6 mg环丙孕酮和300 IU促性腺素。在两个方案中，均根据发情检测进行人工授精（AI）（即，在取出植入物后55小时内检测到发情的母牛在55小时进行授精，之后检测到发情或未检测到发情的母牛在72小时进行授精）。7dEB + P4方案（80.4%）的发情检测风险高于5dCO-Synch + P4方案（36.4%）（P < 0.05）。在初产牛和经产牛中，7dEB + P4方案AI后10天的孕酮浓度高于5dCO-Synch + P4方案（P < 0.05），但在未产牛中两个方案之间没有差异。7dEB + P4方案（49.7%）的每AI妊娠率高于5dCO-Synch + P4方案（35.4%）（P < 0.05）。初产牛的发情检测风险（25.0%）、排卵风险（76.6%）和每AI妊娠率（28.7%）低于经产牛或未产牛。总之，与7dEB + P4方案相比，内洛尔牛采用5dCO-Synch + P4方案后的繁殖性能降低。此外，初产牛的繁殖性状表明，在产犊后早期开始定时AI程序时需要更多关注。
