Table 4.
Effects of AOC and HMB on in vitro GP and MCP at 24 h incubation for different roughage sources
| Roughage | HMB (mg) | AOC (mg) | pH | GP (mL) | c (%/h) | IVOMD (%) | Ammonia-N (mg/dL) | MCP (mg/mL) |
|---|---|---|---|---|---|---|---|---|
| CWR | 0 | 0 | 6.68 | 45.9 | 6.96 | 61.1 | 29.3 | 1.22 |
| 3 | 6.66 | 49.5 | 7.90 | 64.6 | 29.0 | 1.35 | ||
| 6 | 6.65 | 49.8 | 8.29 | 64.9 | 29.0 | 1.21 | ||
| 15 | 0 | 6.65 | 50.8 | 8.35 | 65.9 | 27.9 | 1.36 | |
| 3 | 6.66 | 52.6 | 8.54 | 67.7 | 27.9 | 1.38 | ||
| 6 | 6.65 | 53.8 | 8.65 | 68.9 | 28.4 | 1.29 | ||
| CS | 0 | 0 | 6.62 | 57.1 | 9.42 | 72.9 | 29.2 | 1.07 |
| 3 | 6.63 | 56.6 | 9.64 | 72.4 | 28.0 | 1.20 | ||
| 6 | 6.62 | 57.9 | 9.65 | 73.7 | 26.9 | 1.28 | ||
| 15 | 0 | 6.62 | 56.3 | 8.86 | 72.2 | 27.3 | 1.19 | |
| 3 | 6.62 | 60.0 | 8.60 | 75.8 | 26.5 | 1.31 | ||
| 6 | 6.62 | 59.1 | 9.85 | 74.9 | 27.4 | 1.25 | ||
| Pooled SEM | 0.007 | 0.42 | 0.180 | 0.40 | 0.42 | 0.015 | ||
| Significance of effects (p-value) | ||||||||
| Roughage | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 | <0.01 | ||
| HMB | 0.28 | <0.01 | 0.14 | <0.01 | <0.01 | <0.01 | ||
| AOC | 0.20 | <0.01 | <0.01 | <0.01 | 0.11 | <0.01 | ||
| AOC | Linear | 0.12 | <0.01 | <0.01 | <0.01 | 0.08 | <0.01 | |
| Quadratic | 0.37 | <0.01 | 0.45 | <0.01 | 0.23 | <0.01 | ||
| Roughage×HMB | 0.72 | <0.01 | <0.01 | <0.01 | 0.99 | 0.38 | ||
| Roughage×AOC | 0.66 | 0.03 | 0.09 | 0.03 | 0.14 | <0.01 | ||
| HMB×AOC | 0.13 | 0.16 | 0.07 | 0.15 | 0.04 | <0.01 | ||
| Roughage×HMB× AOC | 0.06 | 0.02 | <0.01 | <0.01 | 0.36 | <0.01 | ||
AOC, Aspergillus oryzae culture; HMB, 2-hydroxy-4-(methylthio)-butanoic acid; GP, gas production; MCP, microbial protein; IVOMD, in vitro organic matter digestibility; c, rate constant of GP (%/h); CWR, Chinese wild rye; CS, corn silage; SEM, standard error of the mean.