Genome association of carcass and palatability traits from Bos indicus-Bos taurus crossbred steers within electrical stimulation status and correspondence with steer temperament 1. Carcass

Abstract

Genome-wide association analyses were conducted using SNP and carcass traits, with and without electrical stimulation separately, of 350 Bos indicus-Bos taurus steers from a designed mapping population consisting of full-sibling families (embryo transfer) and half-sibling families. Four F1 Nellore–Angus sires had progeny in both types of families. Relationships of carcass traits with multiple assessments of temperament (correlation coefficients of unadjusted or residual values), including aggressiveness (willingness to hit an evaluator), nervousness, flightiness (nervousness with running or other movement), gregariousness (willingness to separate from other steers), and overall temperament (all temperament traits assigned as 1 to 9 values; higher numbers indicate worse or less desirable temperament) at 1 year of age and with overall temperament evaluated immediately prior to slaughter were low (0 < |r| < 0.18). Significant SNP associations were detected (False Discovery Rate controlled at 0.05) on BTA 1 with skeletal maturity (n = 1), and BTA 14 (n = 2) with carcass weight. Candidate genes were (skeletal maturity) phospholipase C like 2 (PLCL2) and (carcass weight) neutral sphingomyelinase activation associated factor (NSMAF) and thymocyte selection associated high mobility group box (TOX). Two SNP with association with marbling score were identified on BTA 12—dachshund family transcription factor 1 (DACH1) was a candidate gene. A region from 24.25 to 38.54 Mb on BTA 23 contained 6 SNP with significant associations with lean or overall maturity, which may be the first reported for these traits. Candidate genes on that chromosome included fibrocystin/polyductin (PKHD1), glial cells missing homolog 1 (GCM1), prolactin (PRL), and ring finger protein 144B (RNF144B). All detections of association were in traits measured on the side with no electrical stimulation; it may be that electrical stimulation removes some of the variation permitting detection of association.