Genetic adaptability of livestock to environmental stresses

Abstract

The concept of adaptability revolves around fitness describing relative ability of an individual to survive and reproduce next generation to ensure continued survival of the population and is the result of natural selection over many generations. Current trend in genetic selection has severely eroded the genetic base ignoring the diversity of the production milieu, importance of adaptation, production of multiple products and social value of the livestock. The problem has been compounded with non-capturing of environmental costs though animal genetic resources (AnGR) on extensive and intensive scale are affected by direct impacts of climate change. Unplanned genetic introgression and crossbreeding has contributed to the greatest extent toward the loss of indigenous breeds. The genetic mechanism influencing fitness and adaptation is not well explored and adaptation traits are usually characterized by low heritability. Further, it may be difficult to combine the adaptation traits with high production potential as there seem to be different physiological and metabolic processes involved. Though decision regarding matching genotypes with environment or vice versa will be situation specific, the low and intermediate level of animal production in many parts of the world suggests that increased yields and efficiency will be more environmentally sustainable than extensive goals ensuring genetic diversity, environmental soundness, animal health and welfare, and social viability. Breeding for climate change adaptation or mitigation will not be necessarily different from existing programs. However, the problems associated with measuring the phenotypes relevant to adaptation have to be overcome. Breeding indices should be balanced to include traits associated with heat resilience, fertility, feed conversion efficiency, disease tolerance and longevity in addition to higher productivity, and give more consideration to genotype by environment interactions (GxE) to identify animals most adapted to specific conditions and natural stratification of breeds and species by climatic zones. Favorable correlation suggests that if major importance is placed on performance traits in stressful environments, adaptability traits would not be compromised and thus the most productive and adapted animals for each environment need to be identified for breeding purposes. Recent successes like slick hair gene in cattle, halothane gene in pig asks for extensive efforts for finding significant quantitative trait loci (QTL) for stress and exploitation of heat shock proteins (HSP). Implementation of marker-assisted breeding value estimation (MA-BVE) using dense genome map for highest possible accuracy will be a welcome step. There is a need of extensive study of interaction among the drivers of changes of climate and livestock, studying it in a composite manner. Appropriate organizational structures and adequate funding to support a climate resilient animal agriculture will be vital.