Table 4.

Effect of different ratios of cellulose and starch (C:S) on ruminal fermentation parameters and MCP^a concentration during 24 h of incubation in vitro.

	Time (h)	Acetate (mmol/mol)	Propionate (mmol/mol)	Isobutyrate (mmol/mol)	Butyrate (mmol/mol)	Isovalerate (mmol/mol)	TVFA (mmol/L)	Acetate/propionate	NH3-N (mg/dL)	pH	MCP (mg/g DM)
C:S = 0:100b	6	553.9	220.1	8.78	206.4	10.9	55.5	2.52	1.38	6.50	119.9
	12	510.0	252.0	7.95	211.5	10.9	73.2	2.02	0.45	6.41	120.0
	18	510.6	231.2	8.82	229.8	12.4	88.1	2.22	0.31	6.33	133.8
	24	496.1	241.1	9.21	232.5	13.3	85.8	2.06	2.56	6.26	147.4
C:S = 25:75	6	546.6	222.7	9.24	209.4	12.0	53.1	2.45	4.94	6.64	93.2
	12	510.9	254.6	8.70	214.4	11.3	59.3	2.01	4.00	6.58	94.8
	18	507.4	258.2	8.44	206.9	11.5	78.0	1.97	0.69	6.48	99.4
	24	495.5	251.4	7.95	226.2	11.4	78.8	1.97	2.73	6.39	119.6
C:S = 50:50	6	547.2	221.4	9.30	209.6	12.5	52.9	2.48	7.83	6.71	97.2
	12	521.3	242.5	8.68	215.4	12.2	59.3	2.15	3.12	6.62	104.8
	18	521.2	241.9	7.88	209.8	10.7	68.4	2.16	4.20	6.55	108.0
	24	506.8	240.0	8.58	224.6	11.9	72.8	2.11	4.03	6.49	111.9
C:S = 75:25	6	533.0	220.8	10.61	221.1	14.5	44.1	2.41	11.19	6.78	76.2
	12	510.7	245.0	9.51	222.3	12.5	53.0	2.09	6.33	6.70	99.9
	18	504.9	260.6	8.48	215.5	10.4	68.5	1.94	3.35	6.55	107.9
	24	485.8	271.8	8.96	222.0	11.4	69.1	1.79	2.07	6.48	108.4
C:S = 100:0	6	536.1	240.4	13.31	192.2	18.0	35.1	2.23	17.05	6.85	69.5
	12	522.1	273.5	11.44	177.5	15.5	45.2	1.91	10.62	6.80	76.9
	18	498.5	318.2	9.78	160.5	13.1	54.9	1.57	7.06	6.67	86.2
	24	493.4	323.8	11.62	157.3	13.9	56.8	1.53	7.83	6.61	85.7
SEM		6.70	5.43	0.429	6.05	0.446	3.243	0.061	0.737	0.040	5.065
	C:S	0.03	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
P	Time	<0.0001	<0.0001	<0.0001	0.24	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
	C:S × Time	0.68	<0.0001	0.02	0.001	<0.0001	0.56	0.007	<0.0001	0.99	0.20
Polynomial contrast-C:S	Linear	0.12	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
	Quadratic	0.36	<0.0001	<0.0001	<0.0001	<0.0001	0.05	<0.0001	0.001	0.12	0.35
Polynomial contrast-Time	Linear	<0.0001	<0.0001	0.0002	0.38	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
	Quadratic	0.01	<0.0001	0.0002	0.17	<0.0001	0.004	<0.0001	<0.0001	0.88	0.90

^a MCP, microbial crude protein synthesis;

^bC:S, cellulose:starch.