The effect of live yeast, <i>Saccharomyces cerevisiae</i>, and their metabolites on ciliate fauna, fibrolytic and amylolytic activity, carbohydrate digestion and fermentation in the rumen of goats

Abstract

The influence of live Saccharomyces cerevisiae cells and their metabolites on the number of ciliates and some fibrolytic and amylolytic enzymes, together with the effect on the concentration of volatile fatty acids (VFA), and disappearance of dry matter (DM) and structural carbohydrates in the rumen of three goats was examined. The control diet (1.2 kg DM·d -1 ) was composed of hay (63%), barley meal (31%), and soyabean meal (4%). Two experimental rations consisting of the same components supplemented with either live Saccharomyces cerevisiae (CNCM I-1077) cells or their metabolites (Diamond V XP). The additives were supplied at the rate of 3 and 25 g·d -1 , respectively. The experiment was carried out in a 3 x 3 Latin square design. Enrichment of the control diet with yeast metabolites increased (P<0.05) the total number of protozoa and the number of Diplodinium from 115 to 146×10 4 and from 2.5 to 6×10 4 ·g -1 digesta, respectively. Conversely, the number of representatives of the genus Isotricha decreased over eightfold regardless of the additive used. The activity of carboxymethylocellulase was about 9.4 µM released reducing sugars·g -1 DM·min -1 irrespective of diet, whereas xylan digestion increased from 57.5 to 69.7 and 70.4 µM released reducing sugars·g -1 DM·min -1 when live yeast (P<0.05) or their metabolites (P<0.01) were added, respectively. On the other hand, amylolytic activity decreased from 58 to 50 µM released reducing (P<0.05) sugars·g -1 DM·min -1 when the control diet was supplemented with viable Saccharomyces cerevisiae. Live yeast cells increased the disappearance of neutral detergent fibre (NDF) from 38 to 44.7% after in sacco incubation of hay in the rumen for 16 h (P<0.05). The disappearance of neither DM nor acid detergent fibre was affected by the diet. Yeast metabolites decreased (P<0.01) total volatile fatty acids (VFA), whereas live yeast had no effect. Enrichment of the control diet with 527 KOWALIK B. ET AL.live yeast increased (P<0.05) the molar proportion of acetate from 62 to 64% of total VFA. Both additives elevated the molar proportion of butyrate from 10.5 to 11.9 and 11.3% of total VFA, respectively (P<0.05) and lowered that of propionate. The acetate/propionate ratio in the rumen of goats fed the control diet and the diet supplemented with either live yeast (P<0.01) or their metabolites (P<0.05) was 2.7, 3.1 and 2.9, respectively. The yeast metabolites increased ruminal pH from 6.5 to 6.7. No changes in acidity were found when live yeast were added.

The effect of <i>Saccharomyces cerevisiae</i> on ruminal fermentation in sheep fed high- or low-NDF rations

“…In the present study, the total VFA concentration was low in comparison with results reported by Kowalik et al (2011) for goats fed diets containing 523 g NDF per kg of dry matter. Molar percentages of acetate, propionate and butyrate, as well as the acetate-to-propionate ratio, were not significantly affected by the addition of yeast products.…”

The influence of supplementing heifer diets with <i>Saccharomyces cerevisiae</i> yeast on the activity of polysaccharidases in the rumen

“…The authors found that up to 38% of total cellulolytic activity in the rumen originated from Eudiplodinium maggii, and that this contribution was visibly related to the number of ciliates. Kowalik et al (2011) reported that live S. cerevisiae increase the degradability of structural carbohydrates of meadow hay in the rumen of goats. The authors suggest that live yeast can increase the number of total ciliates and those belonging to the genus Diplodinium.…”

“…Brossard et al (2006) failed to observe a significant effect of live yeast on the fibrolytic and amylolytic activity in the rumen of sheep. In contrast, Kowalik et al (2011) showed that a yeast preparation increased the xylanolytic and cellulolytic activity in the rumen of goats. The cell wall of yeast is a rich source of polysaccharides.…”

“…On the other hand, yeast metabolites contain: B vitamins, organic acids, amino acids, peptides, esters, as well as mannans and β-glucans. These compounds probably also support the growth of bacteria (Callaway and Martin, 1997) and protozoa (Kowalik et al, 2011) in the rumen. The efficiency of nutrient utilization by rumen microbes depends on the profile and activity of their enzymes.…”

“…The beneficial effect of these additives has been associated with their ability to alter rumen fermentation and stimulate microbial growth. Preparations containing S. cerevisiae promote growth of rumen bacteria, particularly cellulolytic and lactate-utilizing bacteria (Callaway and Martin, 1997;Chaucheyras et al, 1997) and stimulate the growth of rumen ciliates (Kowalik et al, 2011). The stimulatory effect of live S. cerevisiae cells on the number of viable bacteria in the rumen appears to be related to the yeast's ability to remove oxygen from rumen fluid, so improving the anaerobic status of rumen digestia (Newbold et al, 1996).…”