Moderation of ruminal fermentation by ciliated protozoa in cattle fed a high-grain diet

Abstract

The objective of this study was to assess the influence of ciliated protozoa on ruminal fermentation in cattle fed high-grain diets. Six ruminally cannulated steers fed a corn-based grain diet (85% concentrate plus 15% alfalfa hay) at 12-h intervals were assigned randomly to two groups, ciliate free and faunated, in a crossover design. Defaunation was by ruminal emptying, omasal flushing, and treatment with sodium sulfosuccinate. Two to 3 weeks after defaunation, the ruminal contents of all steers were sampled before the morning feeding (0 h) and at 1, 2, 4, 6, 8, and 12 h after feeding to measure pH, analyze fermentation products, and monitor counts of ciliated protozoa and lactic acid-producing and-fermenting bacterial groups. Total numbers of ciliated protozoa in the faunated steers averaged 4.3 x 105/g, and the protozoa consisted of nine genera. Ciliate-free steers had lower (P < 0.01) ruminal pHs (pH 5.97) than faunated cattle (pH 6.45); however, the treatment-time interaction was not significant. Ruminal lactate and ammonia concentrations were similar in both groups. The total volatile fatty acid concentration was higher (P < 0.05) in the ciliate-free steers than in the faunated steers and exhibited a treatment-time interaction (P < 0.05). The acetate-to-propionate ratio was higher (P < 0.05) in the faunated group than in the ciliate-free group and showed a treatment-time interaction (P < 0.05). Total anaerobic bacterial counts were about fourfold higher in the ciliate-free group than in the faunated group. Although counts of lactic acid producers were higher and counts of lactic acid fermenters were lower in ciliate-free steers than in faunated steers, the differences were not significant. Ciliated protozoa in cattle fed high-grain diets apparently moderate the ruminal fermentation rate as evidenced by higher ruminal pH values and lower volatile fatty acid concentrations in faunated cattle than in ciliate-free cattle. It appeared that the moderation of the ruminal fermentation rate by ciliated protozoa was attributable to reduced bacterial numbers and possibly reduced activity. * Corresponding author. t Contribution no. 92-491-J from the Kansas Agricultural Experiment Station.

Effect of Milk Allowance on Concentrate Intake, Ruminal Environment, and Ruminal Development in Milk-Fed Holstein Calves

“…In 26 out of the 32 calf × sampling day combinations, the molar proportion of ruminal propionate was equal to or higher than 35 mol/100 mol. Ruminal defaunation has previously been shown to increase ruminal VFA concentrations and the molar proportion of propionate (Eadie et al, 1970;Nagaraja et al, 1992), and although protozoa were not enumerated in the present study, the fermentation profile was generally in agreement with a defaunated rumen.…”

Aspects of rumen microbiology central to mechanistic modelling of methane production in cattle

“…The modifications caused by elimination of protozoa are generally large, but not systematic (see Eugene et al 2004). Protozoa, either directly or indirectly, influence ruminal retention time and passage rate, rumen volume, numbers and types of rumen bacteria present, overall concentration and proportion of VFA present, nitrogen recycling, pH, concentration of ammonia and DM digestibility (Williams & Coleman 1988;Nagaraja et al 1992;Jouany 1996;Williams & Coleman 1997). The exact impact of the presence or absence of protozoa may depend on the diet being fed and the type and number of protozoa present in the rumen.…”

Effect of virginiamycin on ruminal fermentation in cattle during adaptation to a high concentrate diet and during an induced acidosis.

“…Ruminal acidosis leads to rumenitis, liver abscesses, and subsequent decreased perfor-mance (Brent, 1976). Stable ruminal fermentation depends on the establishment of a viable population of lactate-utilizing bacteria and ciliated protozoa (Mackie and Gilchrist, 1979;Nagaraja et al, 1992). Antimicrobial feed additives can facilitate an uneventful transition to a high concentrate diet and enhance the rate and efficiency of growth.…”