Table 6.
Calculated asymptotic maximum gas production (Max.), time at which half of this gas production (T half) was reached and parameter determining the shape of the curve (Shape) for different substrates in the gas production test
| Max. (mL g−1 OM) | T half (h) | Shape | CP, % of OMa | NDF, % of OM | Corr. max. (mL g−1 OM)a | |
|---|---|---|---|---|---|---|
| U. lactuca | 150a | 10.6c | 0.98a | 27 | 31 | 218 |
| Extracted fraction | 172a | 11.0c | 1.02a | 41 | 24 | 274 |
| Palm kernel meal | 248b | 8.3bc | 1.85c | 16 | 67 | 287 |
| Sugar beet pulp | 380c | 4.5a | 1.49b | 9 | 39 | 404 |
| Alfalfa | 174a | 5.3ab | 1.32ab | 21 | 48 | 228 |
| Grass silage | 290b | 7.0ab | 1.38b | 22 | 51 | 345 |
| SEM | 21.6 | 1.22 | 0.12 | – | – | |
| P value | <0.001 | 0.008 | 0.002 | – | – |
Results in columns without the same letter are significantly different (P < 0.05)
aMaximum gas production corrected with an increase of 2.5 mL per percent crude protein (CP) in organic matter (OM) of the feed materials used as substrate, according to Cone and van Gelder (1999). For U. lactuca and extracted fraction, the N to protein conversion factor of 4.62 and 4.72, respectively, was used (Table 4)