title: Net transfer of nutrients to the duodenum and disappearance of n-alkanes in the reticulo-rumen and the hindgut of sheep fed grass/legume combinations.
abstract: An experiment was carried out to examine the effect of increasing the proportion of Wimmera ryegrass hay in a lucerne hay-based diet on net transfer of nutrients to the intestine, and on the disappearance of n-alkanes in the reticulo-rumen and the hindgut of sheep. Following a latin square design, four adult ewes were fed 1:0, 0·33:0·67, 0·67:0·33 and 0:1 proportions of legume and grass. Increasing the proportion of ryegrass in the diet linearly decreased the intake of DM (P= 0·017), organic matter (P= 0·021) and N (P= 0·001). However, neutral-detergent fibre intake was not affected (P= 0·148), nor was its digestibility coefficient (P>0·10). Diet had no effect on duodenal flows of nutrients (P>0·10), although the proportion of N intake (NI) recovered at the duodenum as non-NH₃ N (NAN) increased linearly with Lolium rigidum in the diet (P= 0·002). Full recovery of NI as NAN was achieved at NH₃ concentrations in the rumen below 110 g/l. Microbial N contribution to NAN varied in a quadratic manner (P< 0·05) with the proportion of grass in the diet, although efficiency of microbial synthesis was not affected (P>0·10). Duodenal recovery of consumed n-alkanes was not affected by diet and was complete for those present in higher concentrations in the forages. Isolated rumen bacteria contained significant amounts of n-alkanes, contributing to the duodenal flow of these hydrocarbons in variable proportions depending on the diet consumed.
authors.affiliation: Departamento de Producción Animal y Ciencia de los Alimentos, Universidad de Zaragoza, Miguel Servet 177, 50013 Zaragoza, Spain.
authors.forename: Abdelhafid
authors.initials: A
authors.lastname: Keli
authors.forename: Genaro
authors.initials: G
authors.lastname: Olmos
authors.forename: Antonio
authors.initials: A
authors.lastname: de Vega
authors.forename: José A
authors.initials: JA
authors.lastname: Guada
mesh_terms: D000473:Alkanes / Q000378:metabolism*; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber / Q000008:administration & dosage / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism*; D004063:Digestion; D004386:Duodenum / Q000378:metabolism*; D007887:Fabaceae; D005260:Female; D008129:Lolium; D009584:Nitrogen / Q000378:metabolism; D012417:Rumen / Q000378:metabolism / Q000382:microbiology; D012756:Sheep; D013279:Stomach, Ruminant / Q000378:metabolism* / Q000382:microbiology
chemical_list: D000473:Alkanes; D004043:Dietary Fiber; D004044:Dietary Proteins; D000641:Ammonia; D009584:Nitrogen