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Article Dans Une Revue Journal of Animal Science Année : 2014

Towards an improved estimation of the biological components of residual feed intake in growing cattle

Résumé

Residual feed intake (RFI) is the difference between observed and predicted feed intake. It is calculated as the residuals from a multiple regression model of DMI on the various energy expenditures (e. g., maintenance, growth, activity). Residual feed intake is often cited to be indicative of feed efficiency differences among animals. However, explaining a large proportion of the (phenotypic and genetic) interanimal variation in RFI remains difficult. Here we first describe a biological framework for RFI dwelling on similarities between RFI and energy balance. Alternative phenotypic and genetic statistical models are subsequently applied to a dataset of 1,963 growing bulls of 2 British and 3 Continental breeds. The novel aspect of this study was the use of a mixed model framework to quantify the heritable inter-animal variation in the partial regression coefficients on the energy expenditure traits within the RFI equation. Heritable genetic variation in individual animal regression coefficients for metabolic live weight existed. No significant genetic variation in animal-level regression coefficients for growth or body fat level, however, existed in the study population. The presence of genetic variation in the partial regression coefficient of maintenance suggests the existence of inter-animal variation in maintenance efficiency. However, it could also simply reflect inter-animal genetic variation in correlated energy expenditure traits not included in the statistical model. Estimated breeding values for the random regression coefficient could be useful phenotypes in themselves for studies wishing to elucidate the underlying mechanisms governing differences among animals in RFI.
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Dates et versions

hal-01173629 , version 1 (07-07-2015)

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Davi Savietto, D. P. Berry, Nicolas N.C. Friggens. Towards an improved estimation of the biological components of residual feed intake in growing cattle. Journal of Animal Science, 2014, 92 (2), pp.467-476. ⟨10.2527/jas2013-6894⟩. ⟨hal-01173629⟩
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