1. Finding a proxy for the inhibiting effects of polyunsaturated fatty acids on milk fat in dairy cows
- Author
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Maxin, Gaëlle, Rulquin, Henri, Glasser, Frederic, Unité Mixte de Recherche sur les Herbivores - UMR 1213 (UMRH), VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Institut National de la Recherche Agronomique (INRA)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS), and Institut National de la Recherche Agronomique (INRA)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement
- Subjects
[SDV]Life Sciences [q-bio] ,food and beverages ,[INFO]Computer Science [cs] ,[SHS]Humanities and Social Sciences - Abstract
International audience; Diets supplemented with plant lipids, high in polyunsaturated fatty acids (PUFA), often induce milk fat depression (MFD) in dairy cows. Several trans FA isomers inhibiting milk fat synthesis have been identified, but cannot fully account for diet-induced MFD. There is still debate on which FA isomers and/or other mechanisms are responsible for diet-induced MFD. The experimental approaches meet several limits (availability of pure FA isomers, simultaneous variations in several FA, and modification of rumen metabolism and other nutrients following dietary lipid supplementation), making it almost impossible to identify the FA that are involved in diet-induced MFD. The aim of this study was to identify, using a modeling approach, a proxy of the inhibiting effects of PUFA on milk fat. A database was compiled from published studies of dietary lipid addition in dairy cow diets. It included 38 responses to lipid addition (differences between a lipid-supplemented diet and a control). From diet composition and intake, using published empirical equations, we predicted the changes in nutrient flows (VFA, glucose and proteins) following lipid addition. Then, the milk fat responses to these changes in nutrient flows were predicted using another set of published empirical equations. We thus got a prediction of the milk fat changes induced by the nutrients other than FA. The prediction bias was computed for each response by difference between this prediction and the response of milk fat reported in the publications, and was assumed to be caused by the inhibiting FA. To identify proxies of the inhibiting effect of PUFA, several variables linked to lipid addition (FA intake, duodenal flows of various FA) were regressed on this bias using GLM model. The 2 best proxies (best regressors on the prediction biases of both milk fat yield and content, based on R2 and RMSE) were the intake of 18:2+18:3 and the duodenal flow of 18:2. These results have to be confirmed on a larger database, but this modeling approach seems to be a good alternative to complement experimental studies of milk fat inhibition by dietary PUFA, and overcome some of their limits.
- Published
- 2012