TABLE 3.

Mean effects of by-product inclusion rate on pH and fermentation pattern in the rumen simulation technique (RUSITEC) system.

Parameter	BP35	BP95	SEM	P value
Daily gas production (l/d)	1.97a	1.68b	0.07	0.0388
Daily methane production (mmol/day)	3.92a	3.03b	0.10	<0.0001
Methane production (mmol/omd)	0.30a	0.24b	0.01	<0.0001
Fermentation parameters
pH	6.72	6.79	0.04	0.1323
NH3-N (mg/d)	144.51	140.46	3.52	0.4291
VFA production (mmol/day)
Total volatile fatty acids	38.36a	35.73b	1.26	0.0137
VFA molar proportion (%)
Acetic: propionate ratio	3.55	3.57	0.073	0.8711
Acetic	63.94	64.65	0.003	0.2075
Propionic	18.02	18.14	0.003	0.7882
Butryic	14.94a	13.40b	0.005	0.0039
Estimated H parameters
H production (mmol/day)*	75.91	70.01	2.41	0.0604
H incorporated (mmol/day)*	41.82a	36.46b	0.97	0.0015
H recovery (%)*	55.15a	52.22b	0.93	0.0431

BP35 = Ration containing 35% by-products. BP95 = Ration containing 95% by-products. SEM = Standard error of the mean. ^a,bMeans within a row with different superscript differ (P < 0.05). *H production, incorporation and recovery was calculated from the concentration of individual VFAs as per Marty and Demeyer (1973) without the inclusion of H₂.