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 two periods. During the first period, defaunation was attempted with nonyl phenol ethylene oxide. Defaunation was complete in three sheep and partial in the other three sheep in which a reduced population of a small Entodinium sp. was observed. During the second 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 ammonia 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 two periods. Effects of ciliate protozoa are related to animal performance.

The role of pH on the survival of rumen protozoa in steers

“…However, at the higher feeding frequency, the rumen pH was lower as a result of higher feed intake (Krause & Oetzel, 2006). The largest drop in rumen pH occurred from 0 to 4 h after feeding in both cases being of 0.55 pH units to faunated and 0.50 to defaunated status (Table 2) contrasting with Veira et al (1983) who observed a less abrupt decrease in rumen pH in faunated sheep compared to protozoal free animals. Variation of 0.5-1.0 rumen pH units represents a five to 10 fold change in hydrogen ion concentration in the rumen (Krause & Oetzel, 2006).…”

“…Franzolin & Dehority (1996b) observed that individual variation in the consumption of diets affected the fauna and rumen pH in sheep fed high concentrated diets. In general, values were lower than those observed by Veira et al (1983) from 6.3 to 6.6 for faunated and 5.95 to 6.85 for defaunated sheep receiving corn silage:corn (1:1) diets. Santra & Karim (2002) also observed that the pH and ammonia concentration of rumen liquor decreased while production of total VFA and total nitrogen increased in the absence of rumen ciliate protozoa in lambs.…”

“…This can contribute to accelerate glucose production from starch which potentially may exacerbate acidosis. Veira et al (1983) also observed a less abrupt decrease in rumen pH in faunated sheep compared to ciliate free animals.…”

“…Veira et al (1983) observed a less abrupt decrease in rumen pH in faunated sheep compared to ciliate free animals. Because starch granules are engulfed by protozoa, especially on high concentrated diets, starch degradation is slower (Hristov et al, 2001), resulting in less production of organic acids in the rumen of faunated steers (Santra & Karim, 2002;Santra et al, 2007).…”

Effects of sunflower seed supplementation and different dietary protein concentrations on the ciliate protozoa population dynamics in the rumen of sheep

“…There have been numerous attempts to develop practical total defaunation or fauna reducing technologies for ruminants (Hegarty 1999), but to date none have been totally successful. Experimental total or partial (reduced fauna) defaunation has been shown to increase the intestinal availability of amino acids (Veira et al 1983(Veira et al , 1984, a response that is desirable when intesti- …”