Effects of oil and natural or synthetic vitamin E on ruminal and milk fatty acid profiles in cows receiving a high-starch diet.
Among trans fatty acids, trans-10,cis-12 CLA has negative effects on cow milk fat production and can affect human health. In high-yielding dairy cows, a shift from the trans-11 to the trans-10 pathway of biohydrogenation (BH) can occur in the rumen of cows receiving high-concentrate diets, especially when the diet is supplemented with unsaturated fat sources. In some but not all experiments, vitamin E has been shown to control this shift. To ascertain the effects of vitamin E on this shift of BH pathway, 2 studies were conducted. The first study explored in vitro the effects of addition of natural (RRR-α-tocopherol acetate) and synthetic (dl-α-tocopherol acetate) vitamin E. Compared with control and synthetic vitamin E, the natural form resulted in a greater trans-10/trans-11 ratio; however, the effect was very low, suggesting that vitamin E was neither a limiting factor for rumen BH nor a modulator of the BH pathway. An in vivo study investigated the effect of natural vitamin E (RRR-α-tocopherol) on this shift and subsequent milk fat depression. Six rumen-fistulated lactating Holstein cows were assigned to a 2×2 crossover design. Cows received 20-kg DM of a control diet based on corn silage with 22% of wheat, and after 2 wk of adaptation, the diet was supplemented with 600 g of sunflower oil for 2 more weeks. During the last week of this 4-wk experimental period, cows were divided into 2 groups: an unsupplemented control group and a group receiving 11 g of RRR-α-tocopherol acetate per day. A trans-10 shift of ruminal BH associated with milk fat depression due to oil supplementation of a high-wheat diet was observed, but vitamin E supplementation of dairy cows did not result in a reversal toward a trans-11 BH pathway, and did not restore milk fat content.
INRA, UMR1289 Tissus Animaux Nutrition Digestion Ecosystème et Métabolisme, F-31326 Castanet-Tolosan, France.
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Zened
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Troegeler-Meynadier
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Najar
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Enjalbert
D000818:Animals; D002417:Cattle; D004032:Diet / Q000379:methods / Q000662:veterinary; D004040:Dietary Carbohydrates / Q000378:metabolism / Q000494:pharmacology*; D019587:Dietary Supplements; D005227:Fatty Acids / Q000032:analysis*; D005260:Female; D005766:Gastrointestinal Contents / Q000737:chemistry; D008892:Milk / Q000737:chemistry*; D010938:Plant Oils / Q000494:pharmacology*; D012417:Rumen / Q000737:chemistry*; D012820:Silage; D013213:Starch / Q000378:metabolism / Q000494:pharmacology*; D000074242:Sunflower Oil; D014908:Triticum; D014810:Vitamin E / Q000494:pharmacology*; D014815:Vitamins / Q000494:pharmacology*; D003313:Zea mays
D004040:Dietary Carbohydrates; D005227:Fatty Acids; D010938:Plant Oils; D000074242:Sunflower Oil; D014815:Vitamins; D014810:Vitamin E; D013213:Starch