LAUSR

Abstract Skin thickness was found to be moderately heritable and genetically associated with lamb survival in a previous study on Romney sheep. The aims of this study were to estimate the heritabilities of skin thickness and skin temperature at around 5 and 11 mo of age and determine genetic and phenotypic correlations between them and with production traits such as fat depth, loin-eye muscle depth and width, live weights at weaning, scanning, and 12 mo, and 12-mo fleece weight, in FocusPrime (n = 2,088), Texel (n = 732), Romney (n = 825) and Highlander (n = 1,801) sheep breeds. Heritability estimates of skin thickness at 5-mo old were moderate in FocusPrime (0.39 ± 0.12) and low in Texel and Highlander (0.11 ± 0.15 and 0.13 ± 0.09, respectively). Heritability estimates of skin thickness at 11-mo old were moderate in all breeds (ranging from 0.19 ± 0.07 to 0.29 ± 0.15). Heritability estimates of skin temperature were high in FocusPrime (0.39 ± 0.11), low in Texel (0.17 ± 0.11) and Highlander (0.12 ± 0.06) and almost zero in Romney (0.04 ± 0.03). A tendency in all breeds for negative and favorable correlations was found between skin thickness and skin temperature at 11-mo old sheep. Skin thickness at 11-mo tended to have a positive genetic correlation with fat depth in all breeds except in Texel where the correlation tended to be negative (−0.10 ± 0.34). Genetic correlations of skin thickness at 11-mo old with the weight traits were variate. There tended to be a positive correlation with weaning weight in Texel (0.14 ± 0.34) and Highlander (0.29 ± 0.22). However, there tended to be negative correlations with live weight at scanning and at 12-mo of age in FocusPrime (−0.03 ± 0.18 and −0.13 ± 0.22, respectively) and tended to be positive in Romney (0.09 ± 0.25 and 0.10 ± 0.24, respectively) and Highlander (0.26 ± 0.22 and 0.39 ± 0.21, respectively). Moreover, genetic correlations of skin thickness at 11-mo of age with FW12 tended to be positive in both Romney (0.20 ± 0.22) and Highlander (0.55 ± 0.19). Further studies on the genetic correlations of skin thickness and skin temperature with lamb survival in these breeds are warranted.