Table 2

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