Genetic parameters of hair cortisol as an indicator of chronic stress under different environments in Holstein cows

Chronic stress is a risk factor for variety of physiological disorders because its increased activation the hypothalamic-pituitary-adrenal (HPA) axis; however, it difficult to reveal environmental and genetic effects contributing long-term HPA activity complexity chronic stress. The hair cortisol concentration (HCC) can be used reflect accumulation axis over time. Some studies suggest that HCC might associated with protein (PC) in shaft; no have revealed dynamic relationship between them. In present study, 1,086 samples from 418 Holstein cows were collected, factors on HCC, PC, ratio PC (HCCP) studied. Subsequently, regression analysis curve fitting identify better-performing indicators Additionally, univariate bivariate evaluation estimate components traits genotype by environment interactions (G × E) under different states. results showed are significantly affected color, sampling year, season, whereas HCCP not influenced color. Adjusted HCCP, where confounding excluded, moderately related indicators. Moderate high heritabilities obtained (0.347 0.390 winter summer, respectively), (0.402 0.495 respectively) (0.289 0.460 when animals same season evaluated. A moderate G E interaction was detected this as indicated low or negative correlation trait environments (e.g. heat condition thermoneutral condition). conclusion, color compared other 2 traits; thus, has potential an indicator Hair could monitor response process cattle, well provide better understanding mechanism activity.