Table 2.
Effect of Saccharomyces cerevisiae fermentation product (SCFP) supplementation on ruminal pH and fermentation in finishing heifers
| Item | Treatments1 | SEM | P-value | ||||
|---|---|---|---|---|---|---|---|
| Control | ANT | rSCFP | dSCFP | rdSCFP | |||
| Ruminal pH | |||||||
| Mean | 5.77 | 5.81 | 5.96 | 5.87 | 5.87 | 0.085 | 0.58 |
| Minimum | 5.02c | 5.13bc | 5.30a | 5.21ab | 5.05c | 0.070 | 0.03 |
| Maximum | 6.74 | 6.69 | 6.70 | 6.60 | 6.77 | 0.083 | 0.65 |
| pH < 5.8, h/d | 12.7 | 12.2 | 9.0 | 11.7 | 11.6 | 1.81 | 0.48 |
| pH < 5.6, h/d | 11.6 | 10.4 | 5.6 | 8.6 | 8.7 | 1.80 | 0.09 |
| pH < 5.2, h/d | 4.3 | 2.2 | 0.3 | 2.1 | 2.4 | 1.35 | 0.30 |
| Volatile fatty acids (VFA) | |||||||
| Total, mM | 141.9 | 136.6 | 132.6 | 141.6 | 134.5 | 6.54 | 0.56 |
| Acetate (A), mol/100 mol | 47.2 | 47.2 | 51.8 | 47.3 | 45.1 | 2.32 | 0.06 |
| Propionate (P), mol/100 mol | 28.5 | 31.4 | 29.4 | 30.0 | 26.8 | 5.54 | 0.68 |
| Butyrate, mol/100 mol | 18.6ab | 15.4bc | 13.4c | 16.8bc | 22.3a | 3.40 | 0.01 |
| A:P ratio | 1.86 | 1.74 | 2.10 | 1.76 | 1.88 | 0.367 | 0.58 |
| Lactic acid, mM | 0.19 | 0.11 | 0.12 | 0.08 | 0.08 | 0.060 | 0.38 |
| NH3-N, mM | 9.35 | 9.40 | 11.80 | 7.46 | 9.19 | 2.591 | 0.43 |
| Protozoa, ×105/mL | 3.53b | 2.83b | 9.93a | 2.78b | 4.35b | 1.55 | 0.03 |
a–cDifferent superscripts within a row indicate significant difference (P < 0.05).
1Treatments: 1) control diet (no antibiotics, no SCFP addition), control plus 2) antibiotics (ANT; 330 mg monensin + 110 mg tylosin/d per heifer; top-dressed), 3) ruminal delivery of SCFP (rSCFP; 18 g/d per heifer; top dressed), 4) duodenal delivery of SCFP (dSCFP; 18 g/d per heifer; via duodenal cannula), or 5) combination of treatments #3 and #4 (rdSCFP; 18 g rSCFP + 18 g dSCFP/d per heifer).