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Author: search.filters.author.Dukkipati VSRSubject: search.filters.subject.genetic parameters

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    Heritability estimates and genetic and phenotypic correlations of skin thickness and skin temperature with key production traits in FocusPrime, Texel, Romney and Highlander sheep
    (Oxford University Press on behalf of the American Society of Animal Science., 2025-06-16) Graña-Baumgartner A; Dukkipati VSR; Biggs PJ; Kenyon PR; Blair HT; Pickering NK; Van der Linden DS; López-Villalobos N
    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.
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    Genetic variation in surface temperature measured using infra-red thermography and genetic associations with production traits in grazing dairy cattle
    (Taylor and Francis Group, 2024-01-01) Douie JS; Lopez-Villalobos N; Dukkipati VSR; Udy G
    Increasing global temperatures and the incidence of extreme weather conditions will result in heat stress becoming a greater issue in production animals. Genetic selection and breeding for heat-tolerant animals have been promoted as a possible mitigation strategy in dairy cattle. The objectives of this study were to obtain in-field skin temperature measurements of the eye, muzzle and udder using infra-red thermography to examine the genetic variation in skin temperature within cows of a dairy herd and to estimate the genetic correlations between skin temperature and production traits. Thermal images and herd test records were obtained for the dairy herd at Massey University’s dairy farm 1. Estimates of (co)variances were obtained using the JWAS program with univariate and bivariate animal models. The heritability estimates for the eye, muzzle and udder temperature were low to moderate at 0.20, 0.24 and 0.39, respectively. All genetic correlations between production and temperature traits were positive except for eye temperature with milk yield and protein yield which was negative and weak. These results indicate that it may be possible to select for a greater skin temperature, however, these results need to be validated using a larger sample size.