Heritability estimates and genetic and phenotypic correlations of skin thickness and skin temperature with key production traits in FocusPrime, Texel, Romney and Highlander sheep.

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 five and 11 months 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 months, and 12-month 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-month 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-month old were moderate in all breeds (ranged 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 favourable correlations was found between skin thickness and skin temperature at 11-month old sheep. Skin thickness at 11-months 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-month 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-month 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-month 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.