Table 4.
Effect of different gossypol addition levels on in vitro fermentation characteristics of two rations after 48 h of incubation.
| Item 1 | Ration | SEM 3 | Gossypol (mg/g) | SEM 3 | p-Value | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| HF 2 | LF 2 | 0 | 0.25 | 0.5 | 0.75 | Ration | Dose | I 4 | L 4 | Q 4 | |||
| pH | 6.68 a | 6.61 b | 0.01 | 6.62 b | 6.64 ab | 6.66 ab | 6.67 a | 0.02 | <0.01 | 0.09 | 0.99 | 0.01 | 0.87 |
| NH3-N (mg/dL) | 40.6 a | 37.3 b | 0.31 | 39.3 | 37.9 | 39.0 | 39.2 | 0.40 | <0.01 | 0.22 | 0.05 | 0.91 | 0.07 |
| MCP (μg/mL) | 91.5 | 91.0 | 2.25 | 105.4 a | 91.1 b | 85.5 b | 83.0 b | 3.19 | 0.89 | <0.01 | 0.68 | <0.01 | 0.02 |
| tVFA (mM) | 93.1 a | 85.9 b | 1.09 | 89.6 ab | 90.8 a | 91.8 a | 85.8 b | 1.55 | <0.01 | 0.06 | 0.53 | 0.15 | 0.03 |
| Ace (%) | 51.9 a | 47.2 b | 0.60 | 50.5 a | 49.9 a | 51.1 a | 46.9 b | 0.82 | <0.01 | 0.01 | 0.15 | 0.01 | 0.03 |
| Pro (%) | 18.7 b | 19.7 a | 0.23 | 18.9 b | 20.3 a | 19.3 b | 18.5 b | 0.33 | 0.01 | <0.01 | 0.23 | 0.10 | <0.01 |
| But (%) | 13.0 | 13.0 | 0.16 | 12.4 b | 13.2 a | 13.5 a | 12.9 ab | 0.22 | 0.97 | 0.01 | 0.17 | 0.06 | <0.01 |
| Val (%) | 2.1 | 2.0 | 0.03 | 2.0 | 2.1 | 2.1 | 2.1 | 0.05 | 0.14 | 0.93 | 0.09 | 0.55 | 0.83 |
| BCVFA (%) | 6.0 a | 5.3 b | 0.12 | 6.0 a | 5.0 b | 6.1 a | 5.6 a | 0.16 | <0.01 | <0.01 | 0.03 | 0.96 | 0.13 |
| NGR | 3.6 | 3.6 | 0.03 | 3.6 b | 3.5 b | 3.8 a | 3.6 b | 0.04 | 0.62 | <0.01 | 0.77 | 0.21 | 0.58 |
| FE | 0.75 | 0.78 | 0.01 | 0.79 | 0.76 | 0.75 | 0.76 | 0.012 | 0.14 | 0.31 | 0.31 | 0.18 | 0.34 |
| DG (%) | 97.6 a | 95.9 b | 0.12 | - | 96.8 b | 97.7 a | 95.8 c | 0.15 | <0.01 | <0.01 | 0.66 | <0.01 | <0.01 |
a,b,c Values in a line within the same class without a common superscript are significantly different (p < 0.05). 1 tVFA, total VFA; Ace, acetate; Pro, propionate; But, butyrate; Val, valerate; BCVFA, branched-chain VFA; NGR, the ratio of non-glucogenic-to-glucogenic acids; FE, fermentation efficiency; DG: total disappearance of gossypol. 2 HF, high-forage substrate; LF, low-forage substrate. 3 SEM, standard error of the difference of the means. 4 I, interaction effect; L, linear; Q, quadratic.