Santos Marcelo H, Ferraz Junior Marcos Vinicius C, Polizel Daniel M, Barroso José Paulo R, Miszura Alexandre A, Martins André S, Bertoloni Analisa V, Oliveira Gabriela B, Pires Alexandre V
Department of Nutrition and Animal Production, Faculty of Veterinary and Animal Science, University of São Paulo, Duque de Caxias North, n 225, Pirassununga, São Paulo 13635-000, Brazil.
Department of Nutrition and Animal Production, Faculty of Veterinary and Animal Science, University of São Paulo, Duque de Caxias North, n 225, Pirassununga, São Paulo 13635-000, Brazil; Department of Animal Science, Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo, Pádua Dias Avenue, n 11, PO Box 09, Piracicaba, São Paulo 13418-900, Brazil.
Theriogenology. 2018 Apr 15;111:56-61. doi: 10.1016/j.theriogenology.2018.01.017. Epub 2018 Jan 31.
This study aimed to evaluate the effects of decreasing permanence period of progesterone (P4) inserts from 9 (9d) to 7 (7d) days in timed-AI (TAI) protocol, as well as their reuse on pregnancy per AI (P/AI) during 7d protocol. At the beginning of all protocols, cows received 2 mg of estradiol benzoate (EB) and a vaginal insert containing 1.9 g of P4. In the 7d protocol, the P4 insert was removed, and cows were given 25 mg of prostaglandin F2α, 0.6 mg of estradiol cypionate and 300 IU of eCG 7 days later. In the 9d protocol, the P4 insert was removed, and cows received the same hormones that were administrated in 7d protocol, however, they were applied on the 9 day of the protocol. In the experiment I, 302 suckled Nellore cows were undergone to 7d protocol, and AI was performed 10-14 h later after estrus detection. In the experiment II, 679 suckled Nellore cows were assigned to receive either 7d or 9d protocols. In the experiment III, 999 suckled Nellore cows were assigned to receive either a new P4 insert (CIDR1), or a P4 insert used previously for 7 (CIDR2), 14 (CIDR3), 21 (CIDR4) or 28 (CIDR5) days, and 227 Nellore heifers received a P4 insert used previously for 21 (CIDR4) or 35 (CIDR6) days during the 7d protocol. When 7d protocol was used, 45% of cows exhibited estrus 48 h after P4 removal. Thus, the AI was performed 55 h after P4 removal in experiments II and III when 7d protocol was used. There was no difference in estrus detection rate (72 vs 74%; P = 0.60), ovulation rate (80 vs 88%; P = 0.13) and P/AI (56 vs 54%; P = 0.49) between 7d and 9d protocols, respectively. In the 7d protocol, the P/AI was similar (P = 0.72) using a new P4 insert (47%), or a P4 insert used previously for 7 (48%), 14 (45%), 21 (54%), or 28 (49%) days in Nellore suckled cows. In addition, P/AI was similar (P = 0.15) in heifers that received a P4 insert used previously for 21 (52%), or 35 (61%) days during the 7d protocol. In conclusion, cows submitted to 7d or 9d protocols had similar reproductive performance, and the reuse of P4 inserts up to 6 folds (five in suckled cows plus one in heifers) did not affect reproductive performance of Nellore cattle in 7d protocol.
本研究旨在评估在定时人工授精（TAI）方案中，将孕酮（P4）缓释装置的放置时间从9天（9d）缩短至7天（7d）的效果，以及在7天方案中重复使用这些装置对每次人工授精的妊娠率（P/AI）的影响。在所有方案开始时，母牛接受2毫克苯甲酸雌二醇（EB）和一个含有1.9克P4的阴道缓释装置。在7天方案中，移除P4缓释装置，7天后给母牛注射25毫克前列腺素F2α、0.6毫克环丙孕酮和300国际单位的eCG。在9天方案中，移除P4缓释装置，母牛接受与7天方案相同的激素，但在方案的第9天应用。在实验I中，302头哺乳内罗尔母牛接受7天方案，并在发情检测后10 - 14小时进行人工授精。在实验II中，679头哺乳内罗尔母牛被分配接受7天或9天方案。在实验III中，999头哺乳内罗尔母牛被分配接受新的P4缓释装置（CIDR1），或之前使用7天（CIDR2）、14天（CIDR3）、21天（CIDR4）或28天（CIDR5）的P4缓释装置，227头内罗尔小母牛在7天方案中接受之前使用21天（CIDR4）或35天（CIDR6）的P4缓释装置。当使用7天方案时，45%的母牛在移除P4后48小时出现发情。因此，在实验II和III中使用7天方案时，在移除P4后55小时进行人工授精。7天和9天方案之间的发情检出率（72%对74%；P = 0.60）、排卵率（80%对88%；P = 0.13）和P/AI（56%对54%；P = 0.49）分别无差异。在7天方案中，在哺乳内罗尔母牛中使用新的P4缓释装置（47%）或之前使用7天（48%）、14天（45%）、21天（54%）或28天（49%）的P4缓释装置时，P/AI相似（P = 0.72）。此外，在7天方案中接受之前使用21天（52%）或35天（61%）的P4缓释装置的小母牛中，P/AI相似（P = 0.15）。总之，接受7天或9天方案的母牛具有相似的繁殖性能，并且在7天方案中P4缓释装置重复使用多达6倍（哺乳母牛中5次加小母牛中1次）不影响内罗尔牛的繁殖性能。
