Evolution over time of the agricultural pollution of waters in an area of Salamanca and Zamora (Spain)

The influence on lipid metabolism of dietary soybean oil with 52.6% linoleic acid (C18:2n-6), was studied in 2-year-old, male-castrated Dutch white goats. A medium-chain triglycerides-product (MCT) containing 48.9% caprylic (C8:0) and 41.0% capric acid (C 10:0) was used as control oil. Six goats were fed the diets containing either soybean oil or MCT according to a 21 x 21 days cross-over design. The rations contained about 15% crude fat in the dietary dry matter. The soybean oil diet significantly (P< 0.05) increased the absolute amount of linoleic acid in plasma lipids. The plasma contents ofheptadecanoic acid (C17:0) and heptadecenoic acid (C17:l) were decreased by feeding the soybean oil diet (P < 0.05). The fatty acid composition of red blood cells was not differently affected by the dietary fats. Dietary soybean oil versus MCT significantly (P < 0.05) increased plasma total cholesterol by 47%, HDL cholesterol by 50% and phospholipids by 39%, but left plasma triglycerides and non-esterified fatty acids unchanged (P > 0.05). This study provides evidence that dietary linoleic acid can escape from biohydrogenation in the rumen of goats and shows that the type of dietary fat has a marked impact on lipid metabolism in goats.