Genetic linkage mapping of quantitative trait loci for behavioral and neuroendocrine stress response traits in pigs

Abstract

A QTL analysis of behavioral and neuroendocrine responses to a "novel environment" stress was conducted in a three-generation experimental cross between Meishan and Large White pig breeds. A total of 186 F2 males and 182 F2 females were studied for their behavioral and neuroendocrine reactivity to a novel environment test at 6 wk of age. Locomotion, vocalization, and defecation rate, as well as exploration time, were measured for 10 min. Blood samples were taken immediately before and after the test to measure plasma levels of ACTH, cortisol, and glucose. Animals were typed for a total of 137 markers covering the entire porcine genome. Analyses were performed using two interval mapping methods: a line-cross regression method, where founder lines were assumed to be fixed for different QTL alleles, and a half-/full-sib maximum likelihood method where allele substitution effects were estimated within each half-/full-sib family. Both methods revealed a highly significant gene effect for poststress cortisol level (P < 0.001) and a significant effect for basal cortisol level (P < 0.05) at the end of the q arm of chromosome 7, explaining, respectively, 20% and 7% of the phenotypic variance. Meishan alleles are associated with higher cortisol levels and are partially dominant (for poststress levels) over Large White alleles. Other significant gene effects on biological measures were detected on chromosomes 1 and 17 (ACTH response to stress), 3, 5, and 8 (glucose levels). The SSC 17 QTL explains 12% of the phenotypic variance of poststress ACTH levels, with a suggestive evidence of imprinting effects. Meishan alleles are associated with lower poststress ACTH levels. Gene effects of low amplitude only were found for behavioral reactivity traits. Considering the effects of stress neuroendocrine systems on energy fluxes and protein deposition, and the importance of stress reactivity for meat quality and animal welfare, these results open new perspectives for pig selection.

Detection of�quantitative trait loci for�carcass composition traits in pigs

“…Although the artifactual nature of this result cannot be excluded, it should be noted that positions and estimated QTL effects from one and two-QTL models were rather consistent. Suggestive evidence of linked growth QTL had already been obtained on SSC 7 for growth traits [37] and cortisol levels [16], but with slightly different QTL positions. A "double peak" in the F-ratio profile was also reported by Rohrer [39], with a different most likely position of the second QTL.…”

The cortisol response to ACTH in pigs, heritability and influence of corticosteroid-binding globulin

“…Several clinical studies have shown a relationship between CBG levels or CBG gene polymorphisms and metabolic parameters related to insulin resistance syndrome (e.g. Fernandez-Real et al, 2002;Barat et al, 2005;Richard et al, 2009), and the CBG locus has been shown to be linked with metabolic traits in several studies (see Moisan, 2010and Mormede et al, 2011aand 2011b for review), including in pigs (Desautes et al, 2002;Ousova et al, 2004), and we showed previously that CBG was a better predictor of carcass composition than cortisol levels (Ousova et al, 2004). In most cases, the physiological effects of CBG have been interpreted as resulting from the influence of CBG on the level and bioavailability of cortisol (Perogamvros et al, 2012;Moisan, 2013).…”

Hair cortisol levels determined at different body sites in the New Zealand White rabbit

“…Individual variation in the HPA axis has been well documented in humans and attributed to genetic factors in twin and family studies (Linkowski et al, 1993;Inglis et al, 1999). Genetic factors (Désautés et al, 2002), but also the efficiency of corticosteroid receptors (DeRijk et al, 2002), may influence the bioavailability of corticosteroid hormones.…”