Table 2. Over time impacts of N2 and Ar flushing on rumen pH, TGP, NH3-N and VFA production
Items | 3 h | 9 h | 12 h | 24 h | RMSE | p-value1) |
Ar | N2 | Ar | N2 | Ar | N2 | Ar | N2 | Gas | Time × Gas |
pH | 7.02 | 7.01 | 6.78 | 6.79 | 6.70 | 6.70 | 6.59 | 6.59 | 0.017 | 0.634 | 0.793 |
TGP (mL) | 22.88 | 25.96 | 42.09 | 43.62 | 48.84 | 51.12 | 65.22 | 68.15 | 1.663 | < .001 | 0.781 |
CH4 (mL) | 2.66 | 2.74 | 7.98 | 8.20 | 9.89 | 9.98 | 14.35 | 14.87 | 0.340 | 0.078 | 0.552 |
NH3-N (mg/dL) | 8.24 | 10.66 | 9.38 | 9.88 | 10.56 | 12.30 | 18.96 | 24.65 | 1.897 | 0.001 | 0.081 |
TVFA (mM) | 39.33 | 39.36 | 52.66 | 52.22 | 58.16 | 58.73 | 75.41 | 75.66 | 1.010 | 0.700 | 0.779 |
Acetate (mM) | 25.51 | 25.55 | 34.80 | 34.43 | 38.34 | 38.84 | 49.50 | 49.72 | 0.702 | 0.574 | 0.751 |
Propionate (mM) | 8.27 | 8.26 | 10.79 | 10.70 | 11.97 | 12.02 | 15.35 | 15.46 | 0.192 | 0.669 | 0.686 |
Butyrate (mM) | 3.70 | 3.71 | 4.79 | 4.75 | 5.26 | 5.29 | 6.69 | 6.73 | 0.089 | 0.760 | 0.837 |
Iso-butyrate (mM) | 0.41 | 0.40 | 0.51 | 0.49 | 0.52 | 0.53 | 0.90 | 0.85 | 0.025 | 0.100 | 0.166 |
Valerate (mM) | 0.67 | 0.67 | 0.85 | 0.84 | 0.91 | 0.91 | 1.20 | 1.17 | 0.023 | 0.160 | 0.488 |
Iso-valerate (mM) | 0.77 | 0.77 | 1.03 | 1.01 | 1.13 | 1.12 | 1.77 | 1.73 | 0.027 | 0.145 | 0.570 |
A:P ratio | 3.09 | 3.09 | 3.22 | 3.22 | 3.21 | 3.23 | 3.22 | 3.22 | 0.019 | 0.456 | 0.396 |
p-value for time factor were < 0.001 in all items.
N2, nitrogen gas; Ar, argon gas; TGP, total gas production; NH3-N, ammonia nitrogen; VFA, volatile fatty acids; RMSE, root of mean square error; TVFA, total volatile fatty acids; sum of acetate propionate, butyrate, iso-butyrate, valerate and iso-valerate concentration (mM); A:P ratio, acetate and propionate ratio.