Effect on rumen microbial populations of ammonia treatment of rice straw forage for steers

Abstract

The microbial populations and fermentation characteristics were compared in the rumina of two rumen-cannulated Holstein steers fed untreated rice straw (RS) and concentrate or ammonia-treated rice straw (ARS) and concentrate. The total volatile fatty acid concentrations in the rumina of both steers were significantly higher when they were fed ARS than when fed RS. The molar proportion of butyric acid when ARS was fed increased significantly, compared with the periods when was fed RS. The population density of protozoa varied only insignificantly with RS or ARS diets. But Dasytricha spp. increased with RS and Entodinium spp. increased with ARS. The viable counts of cellulolytic bacteria were higher with ARS than with RS. The viable counts of sulfate reducing bacteria were lower with ARS, compared with the RS diet. Feeding ARS increased the viable bacterial populations such as Eubacterium spp., Fibrobacter succinogenes, Ruminococcus albus, and Succinivibrio spp. But Bacteroides spp. and Butyrivibrio spp. were dominant when RS was fed. © 1989, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.