Influence of main dietary chemical constituents on the in vitro gas and methane production in diets for dairy cows

Table 3 Effects of diets and incubation time on in vitro degradability of NDF (NDFd) and of true DM (TDMd), gas production (GP) and methane (CH₄) production, and predicted values of GP and CH₄ production

	Degradability		Actual GP, ml per:			Actual CH₄ mL per			Predicted GP	Predicted CH₄
	NDFd, g/kg NDF	TDMd, g/kg DM	g DM	g TDMd	g DM	g dNDF	g TDMd	100 mL GP	mL/g DM	mL/g DM
Diet
Reference	567	840	274	325	34.2	168	40.8	12.5	244	38.8
Low NDF	612^A	872^A	288^A	331	34.4	174	39.3	11.9	250	39.6
High NDF	480^B	767^B	228^B	300^B	30.8^B	151^B	39.9	13.5^A	220	35.9
Low CP	545	835	277	333	33.4	169	39.9	12.0	242	38.0
High CP	542	831	255^B	310	34.0	176	41.0	13.3^A	234	37.8
Low lipid	583	845	265	315	33.1	159	39.0	12.3	251	37.2
High lipid	531	826	253^B	304^B	32.2^B	169	38.8	12.5	238	37.9
SEM	10.3	4.2	5.6	7.2	0.53	3.4	0.63	0.40	10.9	2.09
P-value	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	0.025	<0.001	0.33	0.70
P-value of contrasts
Low vs High NDF	<0.001	<0.001	<0.001	<0.001	<0.001	0.002	0.99	<0.001	0.99	0.99
Low vs High CP	0.99	0.99	<0.001	0.009	0.99	0.99	0.99	<0.001	0.99	0.99
Low vs High lipid	0.003	0.028	0.017	0.99	0.99	0.99	0.99	0.99	0.99	0.99
Incubation time
24 h	472	801	250	314	29.6	172	37.0	11.9	214	34.9
48 h	631	860	276	320	36.7	161	42.6	13.2	260	41.5
SEM	10.5	3.5	7.4	8.8	0.59	1.8	0.66	0.54	7.6	1.69
P-value	0.009	0.007	0.14	0.69	0.014	0.046	0.027	0.22	0.06	0.12
RMSE	15.5	7.2	4.0	7.6	0.69	3.2	0.94	0.25	21.9	3.78

Values with different superscripts within column are significantly (P < 0.05) higher (A) or lower (B) compared to the reference diet (containing 361, 158, and 33 g/kg DM of NDF, CP, and lipids)
Low NDF low NDF diet (325 g/kg DM), High NDF high NDF diet (435 g/kg DM), Low CP low protein diet (CP, 115 g/kg DM), High CP high protein diet (CP, 194 g/kg DM), Low lipid low lipid diet (EE, 26 g/kg DM), High lipid high lipid diet (EE, 61 g/kg DM)

ISSN: 2049-1891