Polymorphism at the ovine ₃-adrenergic receptor locus (ADRB3) and its association with lamb mortality

¹ Agriculture and Life Sciences Division, P.O. Box 84, Lincoln University, Canterbury 7647, New Zealand
² Christchurch School of Medicine and Health Sciences, P.O. Box 4345, Christchurch, New Zealand

^* To whom correspondence should be addressed. E-mail: forrestr{at}lincoln.ac.nz.

	Abstract

₃-adrenergic receptors (ADRB3) are guanine nucleotide-binding protein (G-protein)-coupled receptors predominantly found on the surface of adipocytes. They are major mediators of the lipolytic and thermogenic effects of high catecholamine concentrations, in particular nor-epinephrine. Recently, variation in the ovine ₃-adrenergic receptor gene (ADRB3) has been associated with lamb survival in Merino sheep. In this study, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis of part of the ADRB3 intron was used to genotype 13420 lambs (Borderdale N = 351, Corriedale N = 4260, Coopworth N = 1225, Dorset Down N = 663, Dorset down x Coopworth N = 264, Hampshire N = 230, Merino N = 4488, Merino x Coopworth N = 329, Merino x Polwarth N = 226, Polwarth N = 928, Poll Dorset N = 241, Suffolk N = 215) born on 22 different farms throughout the South Island of New Zealand. Univariate and multivariate odds ratios calculated for each of the eight alleles revealed weak to moderate associations of the A and E alleles with cold survival and alleles C and F with cold-related mortality, and a strong association of the D allele with both cold-related mortality and total mortality. This variation at the ADRB3 locus can possibly be exploited as a gene-marker to increase selection accuracy when breeding for more cold-tolerant lambs.

Key Words: ₃-adrenergic receptor, gene-marker, mortality, polymorphism, sheep, survival