Effects of silage fermentation quality on ruminal fluid parameters

Abstract

The effects of using a microbial inoculant (lactic acid producing bacteria Lactobacillus plantarum and Pediococcus acidilactici in mixture with the enzyme cellulase) or a formic acid-based chemical additive on the fermentation quality, aerobic stability and nutritive value of legume–grass silages were examined. Fermentation parameters in ruminal fluid, nutrient digestion, dry matter intake of silages and cattle performance were evaluated. Untreated silage served as control. The addition of the inoculant resulted in well preserved silage with a significantly lower (p < 0.01) pH, acetic acid and butyric acid contents and significantly higher (p < 0.01) lactic acid contents. Inoculation decreased (p < 0.01) protein breakdown as measured by ammonia-N concentration with values of 64.2 (C), 35.4 (I) and 53.6 (A) g kg-1N. The addition of the formic acid-based additive restricted fermentation and successfully preserved water-soluble carbohydrates. Also, the formic acid-based additive resulted in the least aerobic spoilage in silage. Both additives significantly increased dry matter and organic matter digestibility (in vivo) when fed to sheep. Rumen fermentation was affected by the type of silage. When ruminal fluid samples (n = 3) were analyzed, the number of protozoa tended to be higher with A-treated silage. Rumen pH, ammonia-N, total volatile fatty acids (VFA) did not differ between diets in the mean values, but the proportion of acetate was significantly lower (p < 0.05) with I-treated silage and the proportion of propionate was significantly higher (p < 0.01) when I and A silages were fed compared with C silage. Keywords: lactic acid bacteria, fermentation, silage, cattle, ruminal fluid, digestion