Table 6.
Gas production and fermentation parameters of experimental diets containing 40% alfalafa hay and 60% concentrate with increased amounts of Brussels sprouts (BS; 8, 16 and 24% of concentrate fresh matter).
| Item | Diet | SEM 2 | p | ||||
|---|---|---|---|---|---|---|---|
| Control | CAU8 | CAU16 | CAU24 | Lineal | Quadratic | ||
| Gas production parameters 1 | |||||||
| A (mL/g DM) | 280 a | 287 b | 290 b | 283 a | 2.50 | 0.376 | 0.017 |
| c (%/h) | 3.90 | 3.80 | 3.39 | 3.90 | 0.001 | 0.493 | 0.514 |
| lag (h) | 1.10 b | 0.89 ab | 0.91 ab | 0.76 a | 0.09 | 0.043 | 0.725 |
| AGPR (mL/h) | 7.40 | 7.58 | 7.77 | 7.75 | 0.19 | 0.195 | 0.616 |
| DMED (%) | 40.5 | 40.9 | 41.3 | 41.7 | 0.48 | 0.100 | 0.900 |
| Fermentation parameters (8 h) | |||||||
| Total volatile fatty acids (VFA; µmol) | 1284 a | 1354 ab | 1396 b | 1406 b | 30.4 | 0.015 | 0.340 |
| Individual VFA (mol/100 mol) | |||||||
| Acetate (Ac) | 61.1 a | 61.8 b | 62.5 c | 63.0 c | 0.18 | <0.001 | 0.759 |
| Propionate (Pr) | 22.9 b | 22.6 b | 22.0 ab | 21.7 a | 0.18 | <0.001 | 0.797 |
| Butyrate | 12.8 b | 12.6 b | 12.5 ab | 12.3 a | 0.11 | 0.004 | 0.876 |
| Minor VFA 3 | 3.11 | 2.99 | 3.05 | 2.98 | 0.08 | 0.408 | 0.742 |
| Ac/Pr (mol/mol) | 2.69 a | 2.77 a | 2.87 b | 2.92 b | 0.03 | <0.001 | 0.721 |
| NH3-N (mg/L) | 143 | 157 | 149 | 141 | 5.1 | 0.581 | 0.057 |
| CH4 (mL) | 6.90 | 7.41 | 7.68 | 7.28 | 0.24 | 0.213 | 0.087 |
| CH4/VFA (mL/mmol) | 5.40 | 5.52 | 5.52 | 5.21 | 0.23 | 0.577 | 0.372 |
| AFOM (mg/vial) 4 | 114 a | 120 ab | 124 b | 125 b | 2.69 | 0.018 | 0.323 |
| Fermentation parameters (24 h) | |||||||
| pH | 6.79 | 6.79 | 6.79 | 6.78 | 0.01 | 0.827 | 0.745 |
| Total VFA (µmol) | 2446 a | 2603 b | 2618 b | 2631 b | 25.7 | <0.001 | 0.045 |
| Individual VFA (mol/100 mol) | |||||||
| Acetate (Ac) | 61.5 a | 61.9 ab | 62.5 b | 62.8 b | 0.29 | 0.030 | 0.598 |
| Propionate (Pr) | 18.7 b | 18.7 b | 18.3 ab | 17.9 a | 0.16 | 0.042 | 0.712 |
| Butyrate | 15.5 | 15.2 | 15.0 | 15.1 | 0.18 | 0.100 | 0.414 |
| Minor VFA 3 | 4.27 | 4.15 | 4.16 | 4.24 | 0.08 | 0.828 | 0.308 |
| Ac/Pr (mol/mol) | 3.31 a | 3.35 ab | 3.43 b | 3.53 b | 0.04 | 0.021 | 0.843 |
| NH3-N (mg/L) | 189 | 199 | 198 | 205 | 4.5 | 0.142 | 0.332 |
| CH4 (mL) | 14.9 | 15.6 | 15.0 | 15.4 | 0.36 | 0.793 | 0.513 |
| CH4/VFA (mL/mmol) | 6.10 | 5.99 | 5.74 | 5.85 | 0.12 | 0.105 | 0.479 |
| AFOM (mg/vial) 4 | 220 a | 234 b | 235 b | 236 b | 2.35 | 0.026 | 0.264 |
a,b,c Means in the same row with different superscript differ (p < 0.05). 1 Determined in 144-h in vitro incubations with ruminal fluid from sheep; A: potential gas production; c: fractional rate of gas production, lag: is the time needed to start gas production; AGPR: average gas production rate. DMED: dry matter effective degradability estimated for a rumen particulate outflow 0.042 per h. 2 SEM: standard error of the mean. 3 Minor VFA: calculated as the sum of isobutyrate, isovalerate and valerate. 4 AFOM: fermented organic matter estimated from VFA production [28].