Abstract：
This study evaluated the effect of bovine somatotropin (bST) on pregnancy rate (PR) and size of the dominant follicle (DF) on the day of intravaginal progesterone (P4) removal in protocols for fixed-time artificial insemination (FTAI). Bos indicus (Nellore) females (n = 392) were distributed into three groups. The control group (CG; n = 92) received an intravaginal P4 device + estradiol benzoate on day (d)0; prostaglandin F2α on d7 (first application); removal of P4 + estradiol cypionate (EC) + PGF2α (second application) + ultrasound (US) of the DF on d9; the FTAI was performed on d11; and pregnancy diagnosis (PD) was performed on d45. The bST group (bSTG; n = 142) underwent the same protocol as the CG, except that the animals received 125 mg of bST on d7. The equine chorionic gonadotropin (eCG) group (eCGG; n = 158) underwent the same protocol as the CG, except that the animals received 300 IU of eCG on d9. The PRs of the bSTG, eCGG, and CG were 48%, 48%, and 35%, respectively (p < .05); the bSTG and eCGG showed greater PRs, with follicles 6-7.9 mm (p < .05) and 8-8.9 mm in diameter, respectively. The bSTG exhibited a greater dimension of the DF on d9 of the protocol (p < .05). The eCGG had higher PRs with a body condition score (BCS) of 2.5, and the bSTG had a BCS of 3.0 (p < .05). It was concluded that bST increased PR, bST showed better performance in smaller DF and larger follicular diameter on d9 of the protocol, eCG acted better on animals with lower BCSs, and bST can be used in FTAI.
摘要：
这项研究评估了固定时间人工授精（FTAI）方案中去除阴道内孕酮（P4）当天牛生长激素（bST）对妊娠率（PR）和优势卵泡（DF）大小的影响。Bosindicus（Nellore）雌性（n=392）分为三组。对照组(CG;n=92)在第(d)0天接受阴道内P4装置+苯甲酸雌二醇;d7时前列腺素F2α(第一次应用);d9时去除P4+环戊酸雌二醇(EC)+PGF2α(第二次应用)+DF的超声(US);在d11进行FTAI;在d45进行妊娠诊断(PD)。bST组（bSTG;n=142）接受与CG相同的方案，除了动物在d7时接受125mg的bST。马绒毛膜促性腺激素（eCG）组（eCGG;n=158）接受与CG相同的方案，除了动物在d9时接受了300IU的eCG。BSTG的PR，eCGG,CG是48%,48%,35%,分别(p<0.05)；bSTG和eCGG显示出更高的PR，卵泡直径为6-7.9毫米（p<0.05），直径为8-8.9毫米，分别。bSTG在方案的d9表现出更大的DF维度(p<.05)。eCGG具有较高的PRs，身体状况评分（BCS）为2.5，而bSTG的BCS为3.0（p<0.05）。结论是bST增加了PR，在方案的D9上，BST在较小的DF和较大的卵泡直径中显示出更好的性能，eCG对BCS较低的动物表现更好，和bST可以在FTAI中使用。
