Open AccessTHE APPARENT DIGESTIBILITIES OF DRY MATTER, ORGANIC MATTER AND NONAMMONIA NITROGEN IN THE FORESTOMACH, SMALL INTESTINE, AND LARGE INTESTINE OF WETHERS EXPOSED TO A COLD ENVIRONMENT
Author(s) -
John Kelly,
R. J. Christopherson
Publication year - 1989
Publication title -
canadian journal of animal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.377
H-Index - 64
eISSN - 1918-1825
pISSN - 0008-3984
DOI - 10.4141/cjas89-105
Subject(s) - rumen , abomasum , dry matter , zoology , propionate , chemistry , organic matter , ileum , hay , digestion (alchemy) , small intestine , food science , biochemistry , biology , fermentation , chromatography , organic chemistry
Eight shorn yearling Suffolk wethers cannulated in the rumen, abomasum, and terminal ileum were exposed to temperatures of 0 to + 2 °C or 21–25 °C in a crossover experiment to determine effects on the apparent digestibilities of dry matter (DM), organic matter (OM) and nonammonia nitrogen (NAN) in the forestomach and small intestine. Animals were housed in metabolic crates and fed 1600 g d −1 chopped bromegrass hay. After 30 d acclimation, feed, ruminal, abomasal, terminal ileal and fecal samples were acquired for the determination of DM, OM, cell wall constituents (CWC), acid detergent fiber (ADF) and NAN. Rumen volatile fatty acid composition was also determined. Digesta flows at the abomasum and terminal ileum were estimated from the dilution of 103 ruthenium-phenanthroline and 51 chromium-EDTA during continuous infusion of these markers into the rumen. Dry matter (P < 0.10), OM (P < 0.05) and NAN (P < 0.05) flows to the abomasum were increased during cold exposure. The apparent digestibilities of DM (P < 0.10), OM (P < 0.05) and NAN (P < 0.05) in the rumen were decreased during cold exposure but the apparent digestibilities of these components did not change in the small intestine. Consequently, during cold exposure the proportion of OM and NAN digested in the small intestine relative to OM digested in the entire gastrointestinal tract was increased. Total ruminal VF A concentration was not affected by temperature; however, the molar proportion of acetate declined (P < 0.05) and that of propionate increased (P < 0.01). This, together with a greater proportion of the digestion taking place in the small intestine, may improve the efficiency of utilization of metabolizable energy and partly compensate for the decreased ruminal digestion of OM during cold exposure. Key words: Organic matter, nitrogen, digestion, sheep, cold environment