Polymorphism at the β₃‐adrenergic receptor (ADRB3) locus of Merino sheep and its association with lamb mortality

Abstract

Beta3-adrenergic receptors are predominantly found on the surface of adipocytes and are major mediators of the lipolytic and thermogenic effects of high catecholamine concentrations. Recently, variation in the ovine beta3-adrenergic receptor (ADRB3) gene has been reported to be associated with lamb survival. In this study, polymerase chain reaction-single strand conformational polymorphism analysis of part of the ADRB3 intron was used to genotype 4488 Merino lambs born at 10 farms throughout the South Island of New Zealand. Univariate and multivariate odds ratios for each allele revealed a significant association of the E allele with cdd survival and of the D allele with mortality. This variation at the ADRB3 locus may assist in the genetic selection for survival in Merino sheep.

Invited review: Improving neonatal survival in small ruminants: science into practice

“…Some key mechanisms, such as ability to generate heat through non-shivering thermogenesis, have been described above and the genetic basis to cold resistance documented (also see Supplementary Material). There is evidence that a variant of the ovine β3-adrenergic receptor gene (ADRB3) is associated with higher risk of cold-related mortality in Merino sheep in New Zealand (Forrest et al, 2006). However, when extended to 13 other NZ breeds and crosses, the frequency of that gene variant was low or nonexistent, suggesting that it may already have been selected against in the breeds tested.…”

“…These studies will address whether the same issues, risk factors and causes are apparent on farm as have been addressed in experimental studies. Neonatal lamb mortality differs considerably among flocks (Binns et al, 2002;Forrest et al, 2006;Holmøy et al, 2012), with variations between 0% and 20% seen between flocks. Flock mortality rates were strongly correlated between years (Binns et al, 2002;Holmøy and Waage, personal communication), suggesting that flock level risk factors are important.…”

“…However, there is significant between-farm variation with some farms able to reduce mortality to low levels. For example, on New Zealand sheep farms, mortality was reported to vary from 1.4% to 43.5% of all lambs in a survey of 22 farms (Forrest et al, 2006). Similarly, in goat farms in Tamil Nadu, India, annual mortality was reported to range from 2.2% to 30.5% (Thiruvenkadan and Karunanithi, 2007).…”

Extended Haplotype Analysis of OvineADRB3Using Polymerase Chain Reaction Single Strand Conformational Polymorphism on Two Regions of the Gene

“…Surprisingly, little emphasis has been placed on either investigating the full extent of variation in the human gene or how this variation may affect metabolism in other species, despite evidence for extensive variation in the gene in both sheep (Forrest et al, 2006;Yang et al, 2009) and cattle (Hu et al, 2010) and evidence of single-nucleotide polymorphisms (SNPs) in and near the gene in rat, mice, and humans (Entrez SNP, www.ncbi.nlm.nih.gov/snp).…”

“…In pigs, it has been associated with variation in eye muscle area (Hirose et al, 2009), and in New Zealand farmed sheep breeds, variation within the single intron of the ovine ADRB3 has been associated with lamb survival (Forrest et al, 2006), birth weight, growth rate, carcass composition (Forrest et al, 2003), wool staple strength, and wool yield (Forrest et al, 2009).…”