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The Role of Breeding in Positive Welfare Change
Selective breeding will be crucial in meeting global challenges of ensuring food security and environmental and economic sustainability. Animal welfare affects efficiency and productivity and forms an important component of sustainability. The paper will consider the opportunities that breeding offers to improve some of the most intractable welfare challenges and, in doing so, how this will lead to direct economic and environmental benefits.
Three examples will demonstrate the technical feasibility of breeding to improve welfare and will highlight the benefits to wider sustainability (lamb neonatal survival, foot infections (‘footrot’) in sheep and aggression between pigs). Each is a long-standing and routine welfare problem. Significant moderate heritabilities (lamb vigour which contributes to survival, 0.32; footrot, 0.15-0.25, aggression, 0.43) show that each can be improved by selection. New rapid and robust phenotyping methods have led to uptake (footrot) or commercial interest in selection (survival, aggression). Careful choice of selection trait can avoid antagonistic genetic correlations with economic traits (e.g. rg between aggressiveness and growth, 0.29-0.54) or lead to correlated benefits (e.g. rg between footrot and number of lambs reared to weaning, -0.6).
Phenotyping welfare traits can be costly. Examples will be given of how genomic selection or selection on associative effects (heritable effects on growth of group-mates) may circumvent the constraints that phenotyping costs currently pose to selection. Estimation of economic weights is difficult for many welfare traits as their full effects on profitability have not been quantified (e.g. effects on labour requirements and immunocompetence). Economic weights need to be exaggerated in some cases to reflect this or desired gains methodology used. Improving welfare traits by selection presents ethical dilemmas. We argue that the ethical decision is simpler where opportunities for management change are few and unintended changes in other welfare traits are unlikely (e.g lamb survival in unpredictable climates). This situation will be contrasted with the ethical considerations involved in selection against a complex social behavior (e.g. aggression).
Breeding poses both threats and opportunities to welfare. Used appropriately, it can help to improve long-standing welfare problems. The barriers to achieving this are diminishing but still significant and require a greater understanding of correlated effects on economic and non-economic traits and low-cost but information-rich phenotyping methods.
Keywords: breeding; welfare; footrot; survival; aggression