Challenges and strategies for genetic selection of sheep better adapted to harsh environments

10 Pág. ; Extensive sheep farming is often associated with small flocks grazing large areas, delivering limited economic returns compared with the revenue of examples such as dairy or intensive beef cattle farming. However, sheep are a popular choice of livestock in challenging environments where few other production systems are viable (Rust and Rust, 2013). Low input, extensive systems make use of the ability of ruminants to metabolize low-quality, high fiber materials that characterize pastoral grazing. By producing wool, meat, and sometimes dairy, extensive sheep production can deliver high-quality output products from a low-quality input that would otherwise have had little value for sustaining mankind. Furthermore, extensive pastoral systems can arguably be excused from some of the criticisms aimed at factory farming (Frank, 1979). Assuming sustainable stocking rates, extensive sheep farming may be favored in terms of the social and environmental concerns around animal production. However, low input systems are also associated with specific challenges. Outside the support of intensive systems, livestock are expected to survive, produce, and reproduce with little assistance from human intervention or shelter. In addition to requiring a high level of independence, they are also more exposed to the environmental elements such as harsh climates, disease, and parasite challenge. These environmental stressors directly affect production, but the implications for health and welfare should also be considered (Dwyer, 2009). Environmental intervention can be effective (Masters et al., 2023) and should aim to ensure the best outcome for animals wherever possible. In the majority of extensive systems, however, opportunities are limited for being either impractical or too expensive. Animals kept in extensive systems should thus possess an ability to adapt and cope with environmental challenges—a concern of animal breeding and genetics. The issue of adaptability has been previously reviewed according to different ...