Abstract：
Estrogens have proven to be effective in bovine estrus induction protocols. Considering the extensive use of these products in large-scale estrus synchronization, the primary objective of the present study was to assess their effects on pregnancy rate (PR) using a meta-analysis approach. A total of 797 papers were screened from three major databases (PubMed, Web of Science, Scopus). Sixty-one studies were eligible for inclusion in the meta-analysis. The pregnancy status (success or failure) at 30 days post-insemination was considered as the effect size data. The odds ratios (OR) of PR were evaluated by considering the effects of estrogens in groups with or without estrogen intervention. The impact of estrogen (including factors such as type, dose, and time of administration) and animal characteristics (such as breed, type, and parity) was taken into account when assessing the effectiveness of estrogen response as PR. The results showed an OR of 1.25 (95% CI: 1.15-1.36; P = 0.000) for PR in animals that received estrogen compared to cattle that did not receive estrogen. Estradiol benzoate (OR = 1.3) and estradiol cypionate (OR = 1.2), with doses ranging from 1 to 3 mg (OR = 1.13-1.7), significantly increased the OR of PR. In terms of PR, beef cattle exhibited a higher odds ratio (OR = 1.4; P = 0.000) compared to dairy cattle (OR = 1.1; P = 0.09). The administration of estrogens in the estrus synchronization protocol significantly improved PR in both artificial insemination (OR = 1.2; P = 0.000) and embryo transfer (OR = 1.3; P = 0.033) programs. In summary, incorporating estrogens into estrus induction protocols led to an enhancement of the OR of PR among cattle.
摘要：
雌激素已被证明在牛发情诱导方案中是有效的。考虑到这些产品在大规模发情同步中的广泛使用，本研究的主要目的是使用荟萃分析方法评估其对妊娠率(PR)的影响.总共从三个主要数据库中筛选了797篇论文(PubMed，WebofScience,Scopus）。61项研究符合纳入荟萃分析的条件。在授精后30天的妊娠状态(成功或失败)被认为是效应大小数据。通过考虑雌激素在有或没有雌激素干预的组中的作用来评估PR的比值比（OR）。雌激素的影响（包括类型，剂量,和给药时间)和动物特征(如品种，type,和均等）在评估雌激素反应作为PR的有效性时被考虑在内。结果显示，与未接受雌激素的牛相比，接受雌激素的动物的PR的OR为1.25（95％CI：1.15-1.36；P=0.000）。苯甲酸雌二醇（OR=1.3）和环戊酸雌二醇（OR=1.2），剂量范围为1至3毫克（OR=1.13-1.7），显著增加PR的OR。在PR方面,与奶牛（OR=1.1；P=0.09）相比，肉牛表现出更高的优势比（OR=1.4；P=0.000）。在人工授精（OR=1.2；P=0.000）和胚胎移植（OR=1.3；P=0.033）计划中，在发情同步方案中使用雌激素均显着改善了PR。总之,将雌激素掺入发情诱导方案可提高牛的PROR。
