Breeding strategies for resilience of dairy production to weather changes in small ruminants

A potential strategy to address the impact of climate change on sustainability of livestock production is the use of novel animal phenotypes for resilience in breeding schemes. However, antagonistic correlations between resilience and
production level may undermine the potential benefits. The objective of this study was to develop breeding strategies aiming to enhance animal resilience to weather changes and assess the effect on other breeding traits. Weather and
animal data from Spain (dairy sheep) and UK (dairy goats) were used to derive individual phenotypes for resilience and estimate genetic parameters and correlations with other traits. Respective populations with animal records for
performance and resilience traits were simulated assuming a polygenic model and non-overlapping generations, and estimated breeding values for production, climate resilience and functionality traits were combined into a selection
index in each generation. Different scenarios were based on the varying emphasis of the traits included in the breeding goal. For dairy sheep, traits considered were daily milk, fat and protein yields, conception rate and, as resilience trait, protein yield to daily temperature change. A 10-20% relative emphasis on resilience resulted in animals maintaining a high production regardless of weather conditions. For dairy goats, traits were daily milk yield, longevity, mastitis incidence, age at fist kidding and as resilience trait, milk yield to daily temperature change. Despite the antagonistic correlation between milk yield and resilience, an index comprising milk production and functional traits remained unaffected when a 10% emphasis on resilience was considered in the breeding goal. In conclusion, not considering resilience led to performance losses due to weather changes. Therefore, breeding strategies placing a low emphasis on resilience are recommended to reduce losses due to weather change without compromising other traits in the breeding goals