. 2014 Jan 1;27(1):36–45. doi: 10.5713/ajas.2013.13298

Table 3.

Effect of protein source with roughage to concentrate ratio on in vitro volatile fatty acids (VFA), ammonia nitrogen (NH₃-N) and methane production (CH₄)

Protein source¹	R:C² ratio	Total VFA (mM/L)	C₂ (%)	C₃ (%)	C₄ (%)	C₂:C₃ ratio	NH₃-N (mg/dL)	CH₄ production³ (mM/L)
YEFECAP	80:20	65.0^ab	60.5^bcd	28.4^abc	10.8^ab	2.2^cde	26.6^a	21.0^cd
	60:40	64.1^ab	58.2^cd	30.2^ab	11.6^ab	2.0^de	24.5^abc	21.0^cd
	40:60	68.5^a	57.2^cd	30.4^ab	12.4^ab	1.9^de	21.7^bcd	22.3^c
	20:80	65.0^ab	61.6^bc	28.4^abc	10.1^ab	2.2^cd	20.0^cd	23.9^bc
	0:100	56.1^bcd	67.0^a	23.4^de	9.7^b	2.9^a	18.9^d	24.3^bc
SBM	80:20	52.1^cd	56.1^d	32.4^a	11.5^ab	1.7^e	24.9^ab	18.8^d
	60:40	57.1^bcd	60.7^cd	25.3^cde	14.1^a	2.4^bc	24.1^abc	22.0^cd
	40:60	61.4^abc	61.5^bc	27.5^bcd	11.0^ab	2.2^cd	24.0^abc	24.5^bc
	20:80	56.1^bcd	65.6^ab	23.9^cde	10.6^ab	2.8^ab	21.8^bcd	26.2^ab
	0:100	50.1^d	66.4^a	21.6^e	12.0^ab	3.1^a	19.8^dc	28.8^a
SEM		2.89	1.42	1.33	1.17	0.12	1.39	1.01
Comparison
Protein source¹		^**	ns	^*	ns	^*	ns	^*
R:C ratio²		^*	^**	^**	ns	^**	^**	^**
Interaction		ns	^*	^*	ns	ns	ns	ns
Orthogonal polynomial
R:C (linear)		ns	^**	^**	ns	^**	^**	^**
R:C (quadratic)		^**	^*	ns	ns	^**	ns	ns
R:C (cubic)		ns	ns	ns	ns	ns	ns	ns

^a–e

Value on the same row with different superscripts differ (p<0.05),

p<0.05,

^**

p<0.01.

ns = Non-significant, SEM = Standard error of the mean, YEFECAP = Yeast fermented cassava chip protein, SBM = Soybean meal.

PS = Protein source in concentrate.

R:C = Roughage:concentrate ratio.

Calculated according to Moss et al. (2000) CH₄ production = 0.45 (C₂)−0.275 (C₃)+0.4 (C₄).