The effect in sheep of physical form and stage of growth on the sites of digestion of a dried grass

I .The effect of grinding and pelleting S 24 perennial rye-grass (Lolium perenne L.), harvested at two stages of maturity and artificially dried, on the sites of digestion of nitrogenous constituents was studied with sheep equipped with a fistula into the rumen and re-entrant cannulas at the proximal duodenum and terminal ileum.Chopped and pelleted grasses at both stages of maturitywere each givcn at goo g dry matter ( D M ) / z ~ h to each of five shcep; the two forms of the early-cut grass were also given each to four of the five sheep at 1400 g D M / Z ~ h.2. The pelleting process significantly depressed apparent digestibility of total nitrogen in both grasses ( P < 0.05).For the early-cut grass neither physical form nor level of feeding had any significant cffect on N retention; for the medium-cut grass N retention was significantly higher ( P < 0.05) when thc pelletcd form was given.N retention was significantly lower on the medium-cut grass ( P < 0.05) than on the early-cut grass. 3.For individual amino acids the greatest relative increases (intake = 100) at the proximal duodenum were found for mcthionine and cysteine/cystine ( P < 0.001) on all six diets, together with tryptophan ( P at least < 0.01) and lysine ( P at least < 0.05) on five of the diets, and including histidine on the early-cut diets ( P at least < 0.01).At the low level of feeding, incrcase in stage of growth at cutting significantly dcpressed the relative amounts of phenylalanine, lysine, serine ( P < 0.05), histidine, aspartic acid and tyrosine ( P < 0.01) entering the small intestine, and increased those of tryptophan ( P < 0.05).Pelleting of the early-cut grass significantly increased the amounts of methionine entering the small intestine compared with feeding it chopped (P<o.o5); the same was true for phenylalanine at the high level of feeding only.4. The relative amounts of threonine, isoleucine, leucine and arginine disappearing in the small intestine were not significantly affected by physical form, stage of growth or in the casc of the early-cut grass, by level of feeding.At the low level of feeding increase in maturity at cutting significantly lowered uptake of histidine ( P < 0.01) and phenylalanine ( P < 0.05) from the small intestine.With tryptophan, uptake from the small intestine was greater ( P < 0.01) and for lysine was lower ( P < 0 0 5 ) for the medium-cut than for the early-cut material hut only with the chopped form.Pelleting of the medium-cut grass significantly lowered relative uptake of tryptophan ( P < 0 .0 5 ) and increased that of lysine ( P < 0.05) compared with the chopped form.Pelleting of the early-cut grass significantly increased the relative amounts of methionine disappearing in the small intestine ( P < 0.05) at both levels of intake; the same was true for phenylalanine at the higher lcvel of feeding only.j.The apparent digestihilities in the small intestine of total amino acid N in chopped grassgiven at the low level mere 78.7 and 70.1 yu with early-and medium-cut grass respectively.With pelleted rations given in low levels the digestibilities were 75'1 and 72.6 w-ith earlyand medium-cut grass.When the early-cut grass was given at high level of intake, the digestibilitics were 74.9 and 67.4 "/o with chopped and pclleted rations respectively.es of individual amino acids in the small intestine and hetween-diet differences for a given amino acid a high positive correlation between 6 .