Reproductive performance of fixed-time artificial insemination in swine and factors for the technology success

ABSTRACT: Fixed-time artificial insemination (FTAI) is a reproductive technology that aids in obtaining an appropriate time to perform single artificial insemination (AI), thus reducing the number of inseminations per sow bred. FTAI protocols can either be based on estrus detection or day of weaning, aiming to synchronize ovulation using ovulation inducers. The protocols involving estrus detection usually employ porcine luteinizing hormone (pLH) as an inducer and, in general, satisfactory reproductive performance is observed. For protocols based on weaning day, the main hormone used is analog of gonadotropin-releasing hormone such as triptorelin and buserelin. Regardless of the protocol, the number of piglets born is usually not affected by FTAI. However, a possible compromise in the farrowing rate should be considered. The FTAI in gilts requires progestogen treatment for estrus synchronization, increasing the labor requirement and cost of protocol. Some of the benefits of FTAI are a reduced number of semen doses required, advantage of planning the breeding time and; consequently, optimizing labor involved. However, the limitations include a slight reduction in the fertility index due to the compromised farrowing rate in some cases, costs incurred by following the protocol, and difficulty in measuring all the conceptual benefits under commercial conditions. The aim of this review is to approach the reproductive performance of the current protocols of FTAI, considering the benefits and limitations of this technology in swine production.

摘要：固定时间人工授精（Fixed-time artificial insemination，FTAI）是一项旨在确定单次人工授精（artificial insemination，AI）最佳时机的繁殖技术，可降低每头配种母猪的授精次数。固定时间人工授精方案可分为基于发情检测和基于断奶日龄两类，均通过使用排卵诱导剂实现排卵同步化。涉及发情检测的方案通常以猪促黄体生成素（porcine luteinizing hormone，pLH）作为诱导剂，总体而言可获得良好的繁殖性能。基于断奶日龄的方案则主要使用促性腺激素释放激素（gonadotropin-releasing hormone）类似物，如曲普瑞林（triptorelin）和布舍瑞林（buserelin）。无论采用何种方案，固定时间人工授精通常不会影响产仔数。但需注意，其可能会对分娩率造成一定影响。后备母猪（gilts）的固定时间人工授精需使用孕激素类药物（progestogen）进行发情同步化，会增加操作工作量与方案成本。固定时间人工授精的优势包括：所需精液剂量减少、可灵活规划配种时机，进而优化配种作业的工作量。但其局限性同样显著：部分情况下会因分娩率受损而导致繁殖指数小幅下降，方案实施需承担相应成本，且在商业养殖环境中难以完全兑现其理论上的全部效益。本综述旨在探讨当前固定时间人工授精方案的繁殖表现，并结合该技术在生猪养殖中的优势与局限性展开全面分析。