Table 5. Total gas and methane production, degradation of nutrients after 48 h of incubation, ammonia-N, and short-chain fatty acids (SCFA) in the effluent, and efficiency of microbial crude protein synthesis.
| CSa | GSb | p-value | |
|---|---|---|---|
| pH | 6.81 (0.04) | 6.90 (0.03) | < 0.05 |
| Total gas (ml day-1) | 858 (51.2) | 815 (57.8) | n.s. |
| Methane (ml day-1) | 77.2 (4.27) | 117 (13.7) | < 0.05 |
| Degradation (%) | |||
| Organic matterc | 44.1 (0.94) | 47.2 (0.97) | < 0.05 |
| Crude proteinc | 67.4 (1.85) | 66.5 (1.27) | n.s. |
| NDFd | 7.86 (1.83) | 17.7 (3.71) | < 0.05 |
| ADFe | 6.51 (2.17) | 22.6 (1.10) | < 0.05 |
| SCFA (mmol day-1) | |||
| Total | 34.2 (1.34) | 31.9 (2.50) | n.s. |
| Acetate | 13.6 (0.87) | 12.6 (1.03) | n.s. |
| Propionate | 5.08 (0.71) | 6.63 (0.39) | < 0.05 |
| Isobutyrate | 0.32 (0.02) | 0.55 (0.06) | < 0.05 |
| Butyrate | 8.79 (0.64) | 6.00 (0.50) | < 0.05 |
| Isovalerate | 3.05 (0.32) | 2.49 (0.55) | n.s. |
| Valerate | 3.39 (0.26) | 3.65 (0.34) | n.s. |
| Acetate:propionate | 2.72 (0.44) | 1.90 (0.06) | < 0.05 |
| Ammonia-N in the effluent (mmol day-1) | 3.04 (0.18) | 7.41 (0.81) | < 0.05 |
| Efficiencyf | 144 (2.70) | 234 (5.37) | < 0.05 |
Data are expressed as the mean (SD); n ≥4,
aCorn silage,
bGrass silage,
cCorrected for contribution of solid associated microbes,
dNeutral detergent fiber without residual ash after α-amylase treatment,
eAcid detergent fiber,
fg microbial crude protein kg-1 degraded organic matter.