TABLE 5.
Fermentation parameters for consecutive batch culture 2 (CBC2; Experiment 2).
|
Time point (hours) |
P-value |
||||||||||
| Inoculum | 6 | 12 | 18 | 24 | 36 | 48 | SEM | Time | Inoculum | Time*Inoculum1 | |
| Gas volume (ml) | G | 33.3 | 79.6 | 117.0 | 155.8 | 196.1 | 218.2 | 31.46 | <0.001 | 0.355 | (0.226) |
| B | 31.8 | 75.8 | 114.2 | 150.9 | 201.0 | 218.4 | |||||
| M | 30.5 | 77.9 | 120.3 | 149.2 | 180.1 | 219.9 | |||||
| pH | G | 6.67 | 6.67 | 6.66 | 6.61 | 6.52 | 6.44 | <0.001 | <0.001 | 0.128 | (0.377) |
| B | 6.70 | 6.67 | 6.66 | 6.64 | 6.53 | 6.43 | |||||
| M | 6.66 | 6.67 | 6.65 | 6.62 | 6.53 | 6.41 | |||||
| NH3-N (mg/ml) | G | 1.51 | 1.59 | 1.71 | 1.67 | 1.83 | 1.82 | 0.003 | <0.001 | 0.189 | (0.120) |
| B | 1.57 | 1.62 | 1.58 | 1.55 | 1.73 | 1.79 | |||||
| M | 1.49 | 1.67 | 1.63 | 1.70 | 1.77 | 1.74 | |||||
| MCP (μg/ml) | G | 9.9 | 143.5 | 279.3 | 420.9 | 498.8 | 532.2 | 30.19 | <0.001 | 0.531 | (0.087) |
| B | 41.7 | 116.1 | 145.1 | 325.4 | 601.7 | 576.3 | |||||
| M | 76.9 | 145.4 | 297.3 | 514.0 | 486.3 | 489.7 | |||||
| tVFA (mM) | G | 39.9 | 74.1 | 96.30 | 130.3 | 159.4 | 171.5 | 39.36 | <0.001 | 0.128 | (0.976) |
| B | 37.0 | 68.5 | 96.30 | 135.1 | 165.4 | 172.2 | |||||
| M | 42.6 | 71.1 | 96.70 | 127.3 | 161.9 | 172.9 | |||||
| Acetate (mM) | G | 26.2 | 46.3 | 55.6 | 67.7 | 87.3 | 94.9 | 0.74 | <0.001 | 0.544 | (0.929) |
| B | 25.0 | 44.3 | 57.1 | 75.1 | 85.7 | 92.3 | |||||
| M | 29.9 | 46.2 | 58.0 | 70.2 | 88.6 | 96.3 | |||||
| Propionate (mM) | G | 7.4 | 15.7 | 22.4 | 34.9 | 41.8 | 45.5 | 0.25 | <0.001 | 0.612 | (0.904) |
| B | 6.9 | 14.7 | 22.6 | 32.1 | 42.8 | 45.2 | |||||
| M | 7.6 | 15.1 | 22.7 | 31.9 | 42.1 | 45.4 | |||||
| Butyrate (mM) | G | 6.2 | 12.0a | 18.4 | 27.7 | 30.3a | 31.1a | 0.24 | <0.001 | 0.005 | 0.003 |
| B | 5.0 | 9.5b | 16.6 | 27.9 | 37.0b | 34.7b | |||||
| M | 5.1 | 9.8b | 16.0 | 25.2 | 31.2a | 31.3a | |||||
With the exception of pH, mean values shown are normalized for substrate DM (1 g) added to the model. G, Good; B, Bad; M, Mix; SEM, standard error of the mean; NH3-N, ammonia-nitrogen; MCP, microbial crude protein; tVFA, total volatile fatty acids. 1Where an interaction was not significant (P-values shown in brackets) in the model, it was removed from the analysis and the model was re-run. a–cMeans within a column that do not share a common superscript are significantly different (p < 0.05).