Digestion in the Rumen and Amino Acid Supply to the Duodenum of Sheep Fed Ensiled and Fresh Alfalfa

Abstract

A study was conducted with six sheep equipped with rumen and duodenal re-entrant cannulae to investigate differences in duodenal amino acid supply with fresh and ensiled alfalfa. The experiment was conducted as a cross-over design with two 12-d periods consisting of an adaptation phase (5 d) followed by feces collection (5 d), and finally on day 12, 24 h continuous collection of duodenal digesta and sampling of rumen fluid. During the experiment the sheep were restricted on feed to 52 g DM d−1 kg−0.75. Analyses of the forages revealed extensive breakdown of threonine, lysine and other basic amino acids, and high degree of preservation of branched chain amino acids. Relative to the amount consumed, there was a net loss of amino acids at the duodenum with fresh alfalfa but a net gain with silage. The relationship between intake of individual essential amino acids and duodenal recovery was inconsistent. Duodenal recovery of total essential amino acids was 28% higher with fresh than with ensiled alfalfa, a difference which was most pronounced with threonine and lysine. Digestion of organic matter and fiber was unaffected (P > 0.05) by ensiling of alfalfa. Estimates of ruminal pH were higher (P < 0.05) for silage than fresh forage (6.9 vs. 6.7) but VFA concentrations were lower (P < 0.05) for silage (52.1 vs. 64.1 mmol L−1). Rumen ammonia levels were similar for the two forages. The deficit in duodenal supply of essential amino acids with silage is discussed in relation to the problem of silage intake in ruminants. Key words: Alfalfa silage, duodenal amino acids, sheep, rumen digestion

Degradation in the rumen of proteins from fresh lucerne forage in various stages of growth and conserved as silage or hay

“…It remained higher for fresh forages than for silages (except at 2 h), which was in agreement with the results obtained by Mc Donald and Edwards [28] and Flores et al [18]. NH3-N content was nevertheless lower for hay as observed by Mc Donald and Edwards [28] and Vagnoni and Broderick [37].…”

The Significance of Silage Protein Degradation and Plasma Amino Acid Ratios in the Control of Food Intake by Lambs Fed Ensiled and Fresh Alfalfa

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Flones, D. A., PHrr-r-tp, L. E., Vnrna, D. M. aNo IvaN, M. 1986. The significance of silage protein degradation and plasma amino acid ratios in the control of food intake by lambs fed ensiled and fresh alfalfa.

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“…To complete the study an additional amount of fresh alfalfa was prepared during the subsequent crop year ( 1 982) . Harvesting of additional forage was necessary for the conduct of an accompanying study (Flores et al 1986 On the last day of the collection period, samples of jugular blood (7 mL) were collected in EDTA-coated evacuated tubes (Fisher Scientific Ltd., Montreal, Quebec, Canada) for analysis of plasma urea, and in heparinized evacuated tubes for analysis of plasma amino acids. The blood samples were collected before and 3 h after the morning meal.…”

Biotechnology and the improvement of silage (tropical and temperate) rumen digestion: a mini-review

“…There has been no clear picture as to what leads to the lower intake response on silage, although lower figures for rumen biomass formation and limited protein nutrition continue to be implicated (Stern 1986;Flores et al 1986a). In fact, manipulation (either by feeding or by cannula) of the resulting intestinal amino acid supply has resulted in changes in intake and associated N retention (see Table 1).…”