Effects of bacterial cultures, enzymes, and yeast-based feed additive combinations on ruminal fermentation in a dual-flow continuous culture system

Abstract

Bacterial cultures, enzymes and yeast derived feed additives are often included in commercial dairy rations due to their effects on ruminal fermentation. However, the effects of these additives when fed together are not well understood. The objective of this study was to evaluate the changes in ruminal fermentation when a dairy ration is supplemented with combinations of bacterial probiotics, enzymes and yeast. Our hypotheses were that ruminal fermentation would be altered, indicated through changes in volatile fatty acid profile and nutrient digestibility, with inclusion of: (1) an additive, (2) yeast and (3) increasing additive doses. Treatments were randomly assigned to 8 fermenters in a replicated 4 × 4 Latin square with four 10 d experimental periods, consisting of 7 d for diet adaptation and 3 d for sample collection. Basal diets contained 52:48 forage:concentrate and fermenters were fed 106 g of dry matter per day divided equally between 2 feeding times. Treatments were: control (CTRL, without additives); bacterial culture/enzyme blend (EB, 1.7 mg per day); bacterial culture/enzyme blend with a blend of live yeast and yeast culture (EBY, 49.76 mg per day); and double dose of the EBY treatment (2X, 99.53 mg per day). The bacterial culture/enzyme blend contained five strains of probiotics (Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus lichenformis, Bacillus subtillis, and Enterococcus faecium) and three enzymes (amylase, hemicellulase, and xylanase). On d 8-10, samples were collected for pH, redox, volatile fatty acids, lactate, ammonia N and digestibility measurements. Statistical analysis was performed using the GLIMMIX procedure of SAS. Repeated measures were used for pH, redox, VFA, NH3-N and lactate kinetics data. Orthogonal contrasts were used to test the effect of: (1) additives, ADD (CTRL vs EB, EBY and 2X); (2) yeast, YEAST (EB vs EBY and 2X); and (3) dose, DOSE (EBY vs 2X). No effects (p > 0.05) were observed for pH, redox, NH3-N, acetate, isobutyrate, valerate, total VFA, acetate:propionate, nutrient digestibility or N utilization. Within the 24h pool, the molar proportion of butyrate increased (p = 0.03) with the inclusion of additives when compared to the control while the molar proportion of propionate tended to decrease (p = 0.07). In conclusion, inclusion of bacterial cultures, enzymes and yeast to the diet increased butyrate concentration; but did not result in major changes in ruminal fermentation.

Inclusion of Direct-Fed Microbials in Lactating Dairy Cow Diets

“…The additional nutrient flow of protein increases the amount and quality of protein available in the small intestine, where amino acids are absorbed for use by the animal (Yoon and Stern 1995). Recently, we tested yeast (Saccharomyces cerevisiae) and observed no changes in ruminal fermentation and digestibility (Bennett et al 2021).…”

“…Additionally, increases in the proportion of propionate reduce the amount of methane produced, which is both an energetic loss to the animal and an environmental health concern (Jeyanathan et al 2014). Recently, we tested Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus lichenformis, Bacillus subtillis, and Enterococcus faecium and observed no changes in ruminal fermentation and digestibility (Bennett et al 2021). We have also evaluated Lactobacillus plantarum and observed a reduction in ruminal ammonia, which may represent an improvement in ruminal nitrogen utilization (Monteiro et al 2020).…”

Changed Rumen Fermentation, Blood Parameters, and Microbial Population in Fattening Steers Receiving a High Concentrate Diet with Saccharomyces cerevisiae Improve Growth Performance

“…The yeast stimulated the growth of M. elsdenii, which converted lactate into C 3 and C 4 [6,35]. However, the inclusion of yeast in the diet increased C 4 concentration, but did not result in major changes in ruminal fermentation [49].…”

“…This result concurred with findings of Sousa et al [33], who reported that the addition of yeast significantly increased the relative population of R. flavefaciens. The addition of DY increased the growth of cellulolytic bacterial populations, particularly R. flavefaciens and F. succinogenes, while limiting the growth of the lactate-producing bacterium (S. bovis) and increasing rumen fermentation consistency [49]. Ding et al [51] found that adding yeast enhanced the number of bacteria, fungi, protozoa, lactate-utilizing bacteria, and the rate of fiber degradation.…”

Addition of Exogenous Fibrolytic Enzymes to Lactating Dairy Cow Diets

“…This allows more hydrolysis to occur throughout the rumen, carrying on a cycle of more substrate increasing the growth of bacteria, which in turn increases endogenous bacterial enzyme secretions (McAllister et al 2001). Recently, we tested a hemicellulose, xylanase, and amylase mixture, and observed only minor changes in ruminal fermentation, with no increase in ruminal digestibility (Bennett et al 2021). While there is not generally an increase in the extent of nutrient digestibility with the inclusion of enzymes in the diet, there is an increase in the rate of nutrient digestibility.…”