Table 5.

Effects of forage to concentrate ratio and dietary sunflower oil supplement on ruminal methane (CH₄) and carbon dioxide (CO₂) emissions in lactating dairy cows

	Treatment1					P-value3
Item, unit	L	LSO	H	HSO	SEM2	FC	SO	FC×SO
Ruminal CH4
g/d	492	362	404	335	20.4	0.024	0.002	0.16
g/kg OMI4	28.4	21.3	18.7	17.7	1.27	0.002	0.015	0.045
g/kg ruminal DOM5	72.5	57.6	43.9	41.6	3.84	0.001	0.06	0.15
g/kg total tract DOM	40.0	30.0	24.7	24.5	1.74	< 0.001	0.021	0.024
g/kg ECM6	18.9	14.5	14.2	14.5	1.38	0.051	0.08	0.052
% of GE intake	7.20	5.12	4.90	4.36	0.304	0.002	0.005	0.044
Ruminal CO2
g/d	4056	3045	3880	3671	166.9	0.25	0.018	0.07
g/kg OMI	234	177	180	192	9.2	0.09	0.07	0.016
g/kg ruminal DOM	598	465	415	455	29.6	0.027	0.20	0.039
g/kg total tract DOM	331	249	237	266	13.6	0.045	0.13	0.012
g/kg ECM	156	117	136	160	15.3	0.33	0.51	0.036

¹Refers to diets based on low (0.35) or high (0.65) concentrate ratio supplemented with 0 (L and H, respectively) or 50 (LSO and HSO, respectively) g/kg of sunflower oil on a DM basis.

² n = 16 measurements; error degrees of freedom 6.

³FC, effect of forage to concentrate ratio in the diet; SO, effect of sunflower oil supplement; FC × SO, interaction of FC and SO.

⁴OMI, OM intake.

⁵DOM, apparent OM digestion.

⁶ECM, energy-corrected milk.