title: Effect of fat and lactose supplementation on digestion in dairy cows. 2. Long-chain fatty acids.
abstract: Dairy cows fitted with rumen and proximal duodenal cannulae were given diets of 60% hay, 7% soybean and rapeseed meal, and either 33% concentrate (control diet) or 33% milk (lipid-supplemented diet: "milk" diet). Amounts of total long-chain fatty acids consumed, entering the duodenum and excreted in the feces were examined. Long-chain fatty acid intake was 192 and 764 g/d with the control and milk diets, respectively. The duodenal flow of long-chain fatty acids was greater (17.3%) than the amount consumed when the control diet was fed; with the milk diet, there was a net loss (-22.2%), mainly due to a decrease in total C16 and C18 acids. The extent of C18:2 hydrogenation in the rumen was reduced by the high fat ration, but for C18:3, hydrogenation was very high and unchanged. Apparent intestinal digestibility of fatty acids was high, especially on the milk diet (86.1%), although the amount of fatty acids absorbed (60.6 g/kg dry matter intake/d) was three times greater than with the control.
mesh_terms: D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D004041:Dietary Fats / Q000494:pharmacology*; D004063:Digestion / Q000187:drug effects*; D005227:Fatty Acids / Q000378:metabolism*; D005260:Female; D007408:Intestinal Absorption / Q000187:drug effects; D007785:Lactose / Q000494:pharmacology*
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D005227:Fatty Acids; D007785:Lactose