Browsing by Author "Udy G"

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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.
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    The Value of Genetic Improvement Evaluated Using a Whole of Enterprise Market Model
    (MDPI (Basel, Switzerland), 2024-06-28) Lopez-Villalobos N; Wiles P; Udy G; García-Herreros M; Aponte PM
    The net return from milk to the producers is defined as the aggregate market income from dairy products, after deducting all processing and marketing costs. The way to distribute this net return is through the payment system, which is usually based on multiple components, mainly with a reward for fat and protein and, in the case of the New Zealand dairy industry, a penalty for milk volume. Traditionally, the value of genetic improvement is evaluated using selection index theory assuming that there is an unlimited market where all dairy products can be sold in unlimited amounts at a fixed price and therefore economic values for fat and protein are assumed to be independent of demand. The objective of this study was to estimate the value of continuous genetic improvement evaluated using a model encompassing all the dairy producers in the industry where prices of the dairy products were determined by product specific supply-demand curves. Over 10 years of genetic improvement, the present value of the benefit (10% discount rate) was estimated to be $123,000 per farm. The corresponding benefit when the markets were assumed to have fixed commodity prices was $183,000 per farm. The model revealed that systematic genetic gains had a finite duration during which incremental benefits progressively declined and would be exhausted eventually.