The influence of the method of preservation of forages on the digestion in dairy cows. 2. Digestion of organic matter, energy and amino acids in forestomachs and intestines.

Abstract

2. Two dairy cows with duodenal reentrant and rumen cannulae were given diets containing artificially dried and pelleted grass (GP), grass silage treated with formic acid (GSF), grass silage treated with a mixture of formic acid and formaldehyde (GSFF) or grass silage without additive (GS). DM intake was 14.8 to 16.0 kg/day and about 30% of the N in the diets was from grass pellets or silages. Between 45 and 57% of the apparently digested organic matter and between 26 and 41% of the apparently digested energy disappeared before the intestines. The higher values were found with GSF and GS.Total amino acid N reaching the duodenum was between 104 and 134% of intake, highest with GP and GSFF. The amounts of individual amino acids reaching the small intestine were from 75 to 270% of the amounts ingested. High values (>150%) were found for glycine, lysine, methionine and tyrosine; low values (<100%) for arginine, glutamic acid and proline. The amount of S-containing amino acids reaching the intestine was between 123 and 159% of intake, with lowest values for diet GS. Total N disappearing from the intestines was 66.1% of the amount entering the small intestine and 76.8% of the amount ingested. For amino acid N those values were 73.2 and 91.6%. Between 71 and 107% of the ingested S-containing amino acids disappeared from the intestines, least with diet GS. The different digestion of the rations GP and GSFF, compared with GSF and GS, was ascribed to greater flow due to the reduced particle size and protein protection by heat treatment for diet GP, and to protein protection by formaldehyde for GSFF. (Abstract retrieved from CAB Abstracts by CABI’s permission)