Exploring Endogenous and Exogenous Factors for Successful Artificial Insemination in Sheep: A Global Overview

Abstract

Artificial insemination (AI) plays a vital role in animal breeding programs. AI is applied to enhance animal genetics and facilitate the widespread integration of desirable characteristics with a high potential for productivity. However, in sheep, this biotechnology is not commonly practicable due to multi-factorial challenges, resulting in inconsistent outcomes and unpredictable results. Thoughtful selection of semen donors and recipients based on genetic merit deeply impacts ovine AI outcomes. Additionally, endogenous factors such as breed, age, fertility traits, genetic disorders, and cervical anatomy in ewes contribute to ovine AI success. Extensive research has studied exogenous influences on sexual behavior, reproductive health, and hormonal regulation, all impacting ovine AI success. These exogenous factors include techniques like estrus induction, synchronization, semen handling methods (fresh/chilled/frozen), and insemination methods (cervical/laparoscopic), as well as nutritional factors and climatic conditions. This overview of the literature highlights the endogenous and exogenous challenges facing successful ovine AI and proposes strategies and best practices for improvement. This paper will serve as a guide for understanding and optimizing the success of ovine AI.

Keywords: artificial insemination; breeding success; endogenous factors; exogenous factors; sheep.

Figure 1

Interaction between endogenous and exogenous factors and their impact on the success of ovine AI. Genetic factors: [17,18]; age: [19,20,21,22]; cervical anatomy and function: [23,24,25]; semen quality: [26]. TCAI: transcervical artificial insemination; and AI: artificial insemination.

Figure 2

Exogenous factors influencing ovine artificial insemination success. Hormonal factors: [45,46,47]; semen handling and insemination techniques: [48,49]; heat stress: [50]; nutritional stress: [51,52,53].