Table 7.
Fermentation parameters after 24 h of in vitro incubation of diets containing 50% of oat hay and 50% of concentrate either including no seaweeds (control) or different seaweed species harvested in spring and autumn in northern Norway 1.
| Seaweed Species | Harvesting Season | Concentrate | VFA (mmol/g DM) | Molar Proportions (mol/100 mol) | Acetate/Propionate (mol/mol) | NH3-N (mg/100 mL) | CH4 (mL/g DM) | CH4/VFA (mL/mmol) | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Acetate | Propionate | Butyrate | Isobutyrate | Isovalerate | Valerate | ||||||||
| - | - | Control | 5.06 | 62.8 a | 21.2 b | 11.9 b | 0.98 | 1.20 | 1.79 | 2.96 a | 10.2 | 64.6 ab | 12.8 |
| Alaria esculenta | Spring | AS | 4.88 | 65.3b | 19.3 a | 11.3 a | 0.99 | 1.38 | 1.73 | 3.39b | 9.88 | 65.4 b | 13.4 |
| Autumn | AA | 5.02 | 63.8 a | 22.5 c | 10.4 a | 0.88 | 1.03 | 1.49 | 2.84 a | 7.09 | 63.2 a b | 12.4 | |
| Laminaria digitata | Spring | LS | 4.86 | 65.8 b | 19.8 a | 10.5 a | 0.97 | 1.32 | 1.65 | 3.33 b | 9.84 | 64.0 a b | 13.2 |
| Autumn | LA | 4.86 | 64.6 b | 21.8 a | 9.93 a | 0.91 | 1.14 | 1.63 | 2.96 a | 7.57 | 61.9 a | 12.7 | |
| Pelvetia canaliculata | Spring | PS | 4.80 | 64.8 b | 19.4 a | 11.9 b | 0.95 | 1.31 | 1.65 | 3.34 b | 10.1 | 63.6 a b | 13.2 |
| Autumn | PA | 5.06 | 65.0 b | 19.7 a | 11.0 b | 1.04 | 1.36 | 1.81 | 3.30 b | 8.10 | 66.6 b | 13.2 | |
| Saccharina latissima | Spring | SS | 4.86 | 65.2 b | 20.3 a | 10.6 a | 0.98 | 1.31 | 1.65 | 3.22 b | 9.49 | 63.1 a b | 13.0 |
| Autumn | SA | 5.22 | 63.6 a | 21.8 a | 10.6 a | 0.99 | 1.30 | 1.68 | 2.91 a | 7.83 | 65.0 b | 12.4 | |
| Mastocarpus stellatus | Spring | MS | 4.90 | 64.6 b | 19.4 a | 12.0 b | 1.02 | 1.35 | 1.58 | 3.32 b | 10.3 | 65.5 b | 13.4 |
| Autumn | MA | 4.66 | 64.7 b | 19.5 a | 11.9 b | 0.99 | 1.32 | 1.64 | 3.31 b | 9.51 | 61.6 a | 13.2 | |
| Palmaria palmata | Spring | PPS | 5.26 | 64.3 b | 19.7 a | 12.0 b | 1.03 | 1.31 | 1.64 | 3.26 b | 10.4 | 68.4 b | 13.0 |
| Autumn | PPA | 5.26 | 63.8 a | 20.6 a | 11.9 b | 0.96 | 1.22 | 1.51 | 3.10 ab | 8.87 | 67.7 b | 12.9 | |
| Porphyra sp. | Spring | POS | 5.16 | 63.6 a | 19.9 a | 12.6 c | 0.95 | 1.30 | 1.62 | 3.19 b | 9.34 | 67.2 b | 13.0 |
| Autumn | POA | 5.18 | 63.8 a | 19.5 a | 12.6 c | 1.03 | 1.36 | 1.66 | 3.27 b | 8.61 | 66.1 b | 12.8 | |
| Cladophora rupestris | Spring | CS | 5.00 | 63.6 a | 20.0 a | 12.5 c | 0.95 | 1.26 | 1.67 | 3.19 b | 8.44 | 65.2 b | 13.0 |
| Autumn | CA | 5.24 | 63.8 a | 19.6 a | 12.8 c | 0.98 | 1.30 | 1.53 | 3.26 b | 8.95 | 67.5 b | 13.2 | |
| p-value | 0.152 | <0.001 | 0.008 | <0.001 | 0.767 | 0.861 | 0.636 | 0.033 | 0.960 | 0.049 | 0.569 | ||
| SEM | 0.042 | 0.088 | 0.129 | 0.063 | 0.011 | 0.025 | 0.023 | 0.023 | 0.349 | 1.59 | 0.52 | ||
a–c For each parameter, the mean values for each diet not sharing the same superscript differ (p < 0.05).