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

• Published in: Applied and Environmental Microbiology 1992-08, Vol.58 (8), p.2410-2414
• Main Authors: Nagaraja, T.G. (Kansas State University, Manhattan, KS), Towne, G, Beharka, A.A
• Format: Article
• Language: English
• Subjects: ACIDE GRAS VOLATIL; ACIDE LACTIQUE; ACIDO GRASO VOLATIL; ACIDO LACTICO; AMMONIAC; AMONIACO; Animal, plant and microbial ecology; Animals; BACTERIA; Biological and medical sciences; Biotechnology; BOEUF; BOVIN; BUEY; Cattle; Ciliophora - metabolism; Colony Count, Microbial; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; Diet; Edible Grain; FERMENTACION; FERMENTATION; FORMULACIONES; FORMULATION; FOURRAGE GRAIN; Fundamental and applied biological sciences. Psychology; GANADO BOVINO; Grain; GRANOS PIENSO; Hydrogen-Ion Concentration; Lactates - metabolism; Lactic Acid; Male; Microbial ecology; Normal microflora of man and animals. Rumen; PROTOZOA; RUMEN; Rumen - metabolism; Rumen - microbiology; Rumen - parasitology
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.58.8.2410-2414.1992

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 10(5)/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