Comparison of the nutritional regulation of milk fat secretion and composition in cows and goats.

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Comparison of ruminal lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil or fish oil

16 páginas, 5 tablas, 1 figura.Direct comparison of cow and goat performanceand milk fatty acid responses to diets known to inducemilk fat depression (MFD) in the bovine revealsrelevant species-by-diet interactions in ruminal lipidmetabolism. Thus, this study was conducted to inferpotential mechanisms responsible for differences in therumen microbial biohydrogenation (BH) due to dietand ruminant species. To meet this objective, 12 cowsand 15 goats were fed a basal diet (control), a similardiet supplemented with 2.2% fish oil (FO), or a dietcontaining 5.3% sunflower oil and additional starch(+38%; SOS) according to a 3 × 3 Latin square designwith 25-d experimental periods. On the last day of eachperiod, fatty acid composition (by gas chromatography)and bacterial community (by terminal-RFLP),as well as fermentation characteristics, were measuredin rumen fluid samples. Results showed significant differencesin the response of cows and goats to dietarytreatments, although variations in some fermentationparameters (e.g., decreases in the acetate-to-propionateratio due to FO or SOS) were similar in both species.Main alterations in ruminal BH pathways potentiallyresponsible for MFD on the SOS diet (i.e., the shiftfrom trans-11 to trans-10 18:1 and related increases intrans-10,cis-12 18:2) tended to be more pronounced incows, which is consistent with an associated MFD onlyin this species. However, changes linked to FO-inducedMFD (e.g., decreases in 18:0 and increases in totaltrans-18:1) were stronger in caprine rumen fluid, whichmay explain their unexpected susceptibility (althoughless marked than in bovine) to the negative effect ofFO on milk fat content. Altogether, these results suggestthat distinct ruminal mechanisms lead to eachtype of diet-induced MFD and confirm a pronouncedinteraction with species. With regard to microbiota,differences between cows and goats in the compositionof the rumen bacterial community might be behindthe disparity in the microorganisms affected by theexperimental diets (e.g., Ruminococcaceae, Lachnospiraceae,and Succinivibrionaceae in the bovine, andPseudobutryrivibrio, Clostridium cluster IV, Prevotella,and Veillonellaceae in the caprine), which hinderedthe assignation of bacterial populations to particularBH steps or pathways. Furthermore, most relevantvariations in microbial groups corresponded to as yetuncultured bacteria and suggest that these microorganismsmay play a predominant role in the ruminal lipidmetabolism in both cows and goats.This study was supported by INRA (UMR1213; France) and the Spanish Ministry of Economy and Competitiveness (MINECO; AGL2014-54587). P. G. Toral was granted a postdoctoral fellowship from Fundación Alfonso Martín Escudero (Madrid, Spain) and a research contract from the MINECO (Juan de la Cierva program).Peer reviewe

Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys

International audience; The aim of this study was to predict the fatty acid (FA) composition of bulk milk using data describing farming practices collected via on-farm surveys. The FA composition of 1,248 bulk cow milk samples and the related farming practices were collected from 20 experiments led in 10 different European countries at 44 degrees N to 60 degrees N latitude and sea level to 2,000 m altitude. Farming practice-based FA predictions [coefficient of determination (R-2) >0.50] were good for C16:0, C17:0, saturated FA, polyunsaturated FA, and odd-chain FA, and very good (R-2 >= 0.60) for trans-11 C18:1, trans-10 + trans-11 C18:1, cis-9,trans-11 conjugated linoleic acid, total trans FA, C18:3n-3, n-6:n-3 ratio, and branched-chain FA. Fatty acids were predicted by cow diet composition and by the altitude at which milk was produced, whereas animal-related factors (i.e., lactation stage, breed, milk yield, and proportion of primiparous cows in the herd) were not significant in any of the models. Proportion of fresh herbage in the cow diet was the main predictor, with the highest effect in almost all FA models. However, models built solely on conserved forage-derived samples gave good predictions for odd-chain FA, branched-chain FA, trans-10 C18:1 and C18:3n-3 (R-2 >= 0.46, 0.54, 0.52, and 0.70, respectively). These prediction models could offer farmers a valuable tool to help improve the nutritional quality of the milk they produce

Dietary Conjugated Linoleic Acid-Enriched Cheeses Influence the Levels of Circulating n-3 Highly Unsaturated Fatty Acids in Humans

peer-reviewedn-3 highly unsaturated fatty acids (n-3 HUFA) directly and indirectly regulate lipid metabolism, energy balance and the inflammatory response. We investigated changes to the n-3 HUFA score of healthy adults, induced by different types and amounts of conjugated linoleic acid (CLA)-enriched (ENCH) cheeses consumed for different periods of time, compared to dietary fish oil (FO) pills (500 mg, each containing 100 mg of eicosapentaenoic and docosahexaenoic acids—EPA+DHA) or α-linolenic acid (ALA)-rich linseed oil (4 g, containing 2 g of ALA). A significant increase in the n-3 HUFA score was observed, in a dose-dependent manner, after administration of the FO supplement. In terms of the impact on the n-3 HUFA score, the intake of ENCH cheese (90 g/day) for two or four weeks was equivalent to the administration of one or two FO pills, respectively. Conversely, the linseed oil intake did not significantly impact the n-3 HUFA score. Feeding ENCH cheeses from different sources (bovine, ovine and caprine) for two months improved the n-3 HUFA score by increasing plasma DHA, and the effect was proportional to the CLA content in the cheese. We suggest that the improved n-3 HUFA score resulting from ENCH cheese intake may be attributed to increased peroxisome proliferator-activated receptor alpha (PPAR-α) activity. This study demonstrates that natural ENCH cheese is an alternative nutritional source of n-3 HUFA in humans

Lipides alimentaires et métabolisme du tissu adipeux chez les ruminants, les porcs et les rongeurs

National audienc

Effect of age of dairy cows on body composition changes throughout the lactation cycle as measured with deuteriated water

International audienc

The role of dietary fat in adipose metabolism

International audienc