Relationship of physiological resilience to weaning stress and NR3C1 expression to carcass merit and pork quality

Pre-slaughter stress due to transportation, fighting between animals, or lairage time can have a negative impact on meat quality. However, it is unknown if post-natal early-life stress influences carcass merit or pork quality. Given that weaning is a major stressor, this study aimed to examine if gilt piglets exhibiting divergent stress response patterns (resilient or vulnerable) at weaning had differences in carcass or meat quality traits as well as underlying molecular differences in cortisol receptors (NR3C1, NR3C2). Stress resilient gilts exhibited significantly lower live weights at slaughter (P = 0.045) and smaller loin muscle area (P = 0.008) than stress vulnerable gilts. Additionally, several associations were observed between tissue-specific transcript abundance and meat quality traits. Lower NR3C1 transcript abundance in subcutaneous adipose was significantly associated with higher marbling score (P = 0.028), higher 45-min pH (P = 0.012), greater pH decline (P = 0.003), higher subjective color score (P = 0.027), and higher Minolta L* values (P = 0.049). In conclusion, this study indicates weaning stress is not associated with substantive differences in carcass merit or meat quality, and revealed insights into potential molecular mechanisms by which stress affects meat quality through adipose-specific expression of the glucocorticoid and mineralocorticoid receptors.