Polymorphism at the ovine beta3-adrenergic receptor locus (ADRB3) and its association with lamb mortality.

The beta3-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 norepinephrine. Recently, variation in the ovine beta3-adrenergic receptor gene (ADRB3) has been associated with lamb survival in Merino sheep. In this study, PCR-single strand conformational polymorphism analysis of part of the ADRB3 intron was used to genotype 13,420 lambs (Borderdale, n = 351; Corriedale, n = 4,260; Coopworth, n = 1,225; Dorset Down, n = 663; Dorset Down x Coopworth, n = 264; Hampshire, n = 230; Merino, n = 4,488; Merino x Coopworth, n = 329; Merino x Polwarth, n = 226; Polwarth, n = 928; Poll Dorset, n = 241; and Suffolk, n = 215) born on 22 farms throughout the South Island of New Zealand. Univariate and multivariate odds ratios calculated for each of the 8 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 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.