Forages Levels of substitution for Glycerine Regression Equations R2 p-value 0% 30% 50% 70% Methane production (CH4, mL g-1) Elephant grass 0.77c 15.93b 19.27b 19.92 Ŷ =3.604-0.276x 0.84 <0001 Sugar cane 2.18c 8.44d 9.28c 8.94c Ŷ =2.241-0.277x-0.002x2 0.71 0.0452 Corn silage 9.04b 11.91c 19.42b 13.27b Ŷ =8.375-0.310x-0.003x2 0.58 0.0662 Brachiaria grass 25.20a 23.70a 20.53a 20.10a Ŷ=25.366+0.079x 0.74 0.0003 Carbon Dioxide (CO2, mL g-1) Elephant grass 9.97c 103.94a 120.42a 120.92a Ŷ =23.790-1.600x 0.80 <.0001 Sugar cane 32.24b 65.61b 71.25b 56.04b Ŷ=31.963-1.769x-0.020x2 0.61 0.0193 Corn silage 39.55a 46.83c 72.25b 58.92b Ŷ =40.596-0.367x 0.54 0.0064 Brachiaria grass 4.86d 5.23d 5.23c 7.36c Ŷ=4.510-0.031x 0.64 0.0018 Ammonia Nitrogen(N-NH3, mL g-1) Elephant grass 21.46a 17.73a 11.90a 8.40a Ŷ =22.112+0.192x 0.92 <.0001 Sugar cane 0.06c 2.56c 3.50c 3.26c Ŷ =0.553-0.047x 0.80 <.0001 Corn silage 6.53b 2.63c 1.40d 0.70d Ŷ =5.963+0.083x 0.88 <.0001 Brachiaria grass 6.36b 6.03b 6.73b 5.50b Ŷ=6.453+0.007x 0.06 0.4587
*Means in the same column with different letters differ statistically by the Tukey test at 5% probability.
Table 2: Mean values, probability (p-value) and regression equations illustrating the effects on production of CH4 (mL g-1), CO2 (mL g-1) and N-NH3 (mL g-1) when different levels of glycerin.