Table 2.
Effects of Saccharomyces cerevisiae on rumen pH and volatile fatty acids.
| Item | Diet | Dose of yeast | Response | Mean pH of treatment groups | Source |
|---|---|---|---|---|---|
| Santa Ines lambs | F:C was 40:60 | Inactive dry yeast at 4.87%, 9.73%, and 14.60% of diets | No effects on pH | 5.83 | Rufino et al. (2013) |
| Dry Holstein cows | F:C was 60:40 | Live dried yeast 3.0 g/cow per d | Increased ruminal pH | 6.26 | Křížová et al. (2011) |
| Primiparous Holstein cows | Low starch (F:C was 50:50); high starch (F:C was 40:60) |
Inactivated dry yeast at 15 g/cow per d | Increased ruminal pH | Low starch, 6.36; high starch, 6.08 |
Dias et al. (2018) |
| Malpura lambs | High starch diet (no forage) | Yeast at 9.0 × 107 CFU/kg body weight | No effects on pH | 6.59 | Bhatt et al. (2018) |
| Holstein bull calves | Milk and starter grains (no forage) | 0.5% and 1% of yeast fermentation product on an as-fed basis in starter diet and milk | Increased butyrate concentration; no effect on pH | 5.69 | Xiao et al. (2016) |
| Feedlot cattle | High grain | 10 g of E. faecium + S. cerevisiae/steer per d (6 × 108 CFU/g) | No effects on pH | 5.85 | Yang et al. (2004) |
| Multiparous Holstein cows | F:C was 60:40 | 0.5 g of active dry yeast/cow per d (1010 CFU/d) | Increase in ruminal pH; increased butyrate concentration | 6.53 | Thrune et al. (2009) |
| Holstein cows | F:C was 40:60 | 60, 120 or 180 g of yeast fermentation product/cow per d | No effects on pH | 6.34 | Zhu et al. (2017) |
| Lactating Holstein cows | High concentrate | 10 g of yeast culture/cow per d | No effects on pH; decreased lactic acid concentration | 6.0 | Erasmus et al. (1992) |
| Charolais bulls | High concentrate | 5 g of live yeast/bull or (1 × 1010 CFU/bull per d) | No effects on pH; increased acetate and butyrate concentrations; increased acetate:propionate ratio | 5.89 | Magrin et al. (2018) |
| Finnish Ayrshire cows | F:C was 50:50 | 0.5 g of live yeast/cow per d (1010 CFU/d) | No effects on pH | 6.65 | Bayat et al. (2015) |
| In vitro fermentation (Rumen fluid collected rumen-fistulated Assaf sheep) | High forage and high concentrate | 5 × 109 CFU inactivated and 109 CFU live yeast/L of medium | Live yeast decreased ruminal pH; inactivated yeast did not affect pH | High forage, 6.64; high concentrate, 6.7 | Opsi et al. (2012) |
F:C = forage:concentrate ratio.