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Influence of percentage of concentrate and dietary fat suplementation on duodenal flow of fat and on milk fat composition in response to t10,c12-CLA infusion in dairy goats

Abstract : The main objective of this work was to study the influence of the percentage of concentrate combined with dietary fat supplementation on the duodenal flow of fiber and fat, dairy performance, and milk fatty acid (FA) profile of dairy goats. We have also studied the effects of the duodenal infusion of t10,c12-CLA and the interaction with the dietary factors described above on fat yield and FA profile of goat milk. In the bibliography, we quantified the influence of oilseed supplementation, according to the type (seeds vs. oil) and the source of the oilseed on dairy performance and on milk composition. We created a data base that pooled information from published articles on dairy cows only, because studies on dairy goats were limited. The changes in milk yield caused by dietary fat were dependent on stage of lactation. The fat addition depressed the milk fat content (MFC), mainly when fed as oil; we also observed an increase in the proportion of trans-C18:1 in the milk fat. The source of dietary fat had less influence on dairy performance than on the profile of long-chain FA. In the experimental study, two trials on mid-lactation dairy goats were undertaken, to link changes in duodenal profile of FA to those in milk. The experimental design was factorial and it combined the percentage of concentrate (low: 45% vs. high: 65% of diet dry matter) and fat addition (Trial 1: control without added fat vs. rolled canola seeds) or fat source (Trial 2 : rolled canola seeds vs. extruded soybeans). Contrary to results with dairy cows, MFC was depressed neither by high-concentrate diets nor by fat supplementation, nor by their interaction. However, the percentages of trans-C18:1 (especially of t11) and of c9,t11-CLA in duodenal content and in milk were increased by these factors and their interaction. The source of dietary fat did not affect dairy performance. Percentages of total trans FA were higher in milk from goats fed canola seeds than soybeans, but it is difficult to separate the effects of fat source from those of total FA intake. The duodenal and the fecal flow of fibers were decreased by high-concentrate diets, but not by supplemental fat, probably because fat content of experimental diets was not higher enough and/or FA release from seeds was not fast enough to have a deleterious effect on ruminal cellulolytic microbes. The reasons for the difference in the response of goats and cows to fat supplementation are not completely understood, but difference in the response of milk fat synthesis to trans FA could be a part of the explanation. The t10,c12-CLA strongly inhibits the de novo synthesis of FA in the bovine mammary gland, but the duodenal infusion of this FA did not depress MFC in goat milk independently of the diet, despite its transfer in milk. However, this FA reduced the capacity of desaturation in the mammary gland in both species. In dairy goat, high-concentrate diets, especially when supplemented in lipids, increased the yield of milk, milk fat, t11-C18:1 and of c9,t11-CLA. Besides, milk FA profile can be modulated by the type of oilseed added to the diet.
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https://pastel.archives-ouvertes.fr/pastel-00001929
Contributor : Ecole Agroparistech <>
Submitted on : Thursday, September 28, 2006 - 8:00:00 AM
Last modification on : Tuesday, May 28, 2019 - 3:33:59 PM
Long-term archiving on: : Thursday, September 30, 2010 - 7:29:43 PM

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Patricia Vilhena Dias de Andrade. Influence of percentage of concentrate and dietary fat suplementation on duodenal flow of fat and on milk fat composition in response to t10,c12-CLA infusion in dairy goats. Life Sciences [q-bio]. INAPG (AgroParisTech), 2006. English. ⟨NNT : 2006INAP0004⟩. ⟨pastel-00001929⟩

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