Table 4.
Effect of pasture type and season on in vitro methane (CH4) output.
| Autumn | Spring | p-Value | ||||||
|---|---|---|---|---|---|---|---|---|
| Variable | HS | LS | HS | LS | SEM | P | S | P × S |
| CH4 (mL/100 mL TGP) | 15.7c | 17.3a | 15.6c | 16.4b | 0.13 | *** | * | n.s. |
| CH4 production at 6 h (mL) | 16.4 | 16.2 | 17.0 | 17.1 | 1.13 | n.s. | n.s. | n.s. |
| CH4 production at 12 h (mL) | 25.3 | 24.5 | 25.6 | 25.8 | 1.70 | n.s. | n.s. | n.s. |
| CH4 production at 24 h (mL) | 33.2 | 33.4 | 34.9 | 34.1 | 0.65 | n.s. | n.s. | n.s. |
| Predicted Michaelis–Menten parameters for CH4 production | ||||||||
| A | 43.8b | 59.5ab | 61.8a | 51.0ab | 3.37 | n.s. | n.s. | * |
| C | 0.069a | 0.038b | 0.037b | 0.057ab | 0.0046 | n.s. | n.s. | ** |
| K | 9.40 | 20.6 | 18.5 | 13.0 | 2.75 | n.s. | n.s. | n.s. |
| n | 1.22a | 0.98b | 0.99b | 1.11ab | 0.044 | n.s. | n.s. | * |
| ta | 3.81 | 6.20 | 5.72 | 4.46 | 0.622 | n.s. | n.s. | n.s. |
| tc | 23.0 | 69.5 | 60.4 | 38.4 | 11.57 | n.s. | n.s. | n.s. |
HS: high sugar pasture; LS: standard cultivar pasture; SEM: standard error of the mean; P: pasture type; S: season; P × S: interaction between pasture type and season; TGP: total gas production; A: asymptotic methane production (mL/g OM); C: degradation rate at half-life (h−1); n: shape of the curve; K; ta; tc: time to produce 50, 25 and 75% of methane production, respectively; p *: p ≤ 0.05; **: p ≤ 0.01; ***: p ≤ 0.001; n.s.: not significant; Values on the same row followed by different letters present significant differences.