Rumen Ciliate Protozoa: Effects on Digestion in the Stomach of Sheep

Abstract

Six wethers, each fitted with a rumen cannula and duodenal reentrant cannula, were used to study effects of ciliate protozoa on rumen digestion and metabolism. A corn:corn silage (1:1) diet was fed for 2 periods. During the 1st period, defaunation was attempted with nonyl phenol ethylene oxide. Defaunation was complete in 3 sheep and partial in the other 3 sheep in which a reduced population of a small Entodinium sp. was observed. During the 2nd period the sheep were inoculated with ciliate protozoa, which established a large population in all animals. Apparent digestion in the stomach of organic matter and starch was higher when a large protozoal population was present. Amino acid flow through the duodenum was greater in defaunated animals. A large population of ciliates was associated with increases in both rumen NH3 and plasma urea but had a stabilizing effect on ruminal pH. Volatile fatty acids were higher in the defaunation period, but there were only small differences of molar proportions of the acids between the 2 periods. Effects of ciliate protozoa are related to animal performance.