title: Effects of high-sugar ryegrass silage and mixtures with red clover silage on ruminant digestion. 2. Lipids.
abstract: The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford x Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 x 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C18:0 and total C18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage.
authors.affiliation: Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK. michael.lee@bbsrc.ac.uk
authors.forename: M R F
authors.initials: MR
authors.lastname: Lee
authors.forename: P L
authors.initials: PL
authors.lastname: Connelly
authors.forename: J K S
authors.initials: JK
authors.lastname: Tweed
authors.forename: R J
authors.initials: RJ
authors.lastname: Dewhurst
authors.forename: R J
authors.initials: RJ
authors.lastname: Merry
authors.forename: N D
authors.initials: ND
authors.lastname: Scollan
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004063:Digestion / Q000502:physiology*; D004386:Duodenum / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D050356:Lipid Metabolism; D008129:Lolium / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D012820:Silage / Q000032:analysis*; D029921:Trifolium / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004040:Dietary Carbohydrates; D005227:Fatty Acids