Table 4.

Effects of forage to concentrate ratio and dietary sunflower oil supplement on rumen fermentation characteristics in lactating dairy cows

	Treatment1					P-value3
Item, unit	L	LSO	H	HSO	SEM2	FC	SO	FC×SO
pH	6.61	6.51	6.03	6.26	0.089	< 0.001	0.37	0.033
Ammonia-N, mmol/L	4.90	6.29	2.80	2.70	0.622	0.004	0.34	0.28
Total VFA, mmol/L	109	105	123	109	3.8	0.003	0.004	0.038
Molar proportions, mmol/mol
Acetate	658	648	594	592	6.7	< 0.001	0.25	0.43
Propionate	180	185	231	224	16.2	0.032	0.96	0.71
Butyrate	111	121	125	130	14.1	0.44	0.64	0.88
Isobutyrate	8.89	8.46	7.20	8.00	0.360	0.021	0.61	0.12
Valerate	16.3	15.2	19.0	19.5	0.67	0.002	0.65	0.28
Isovalerate	15.9	15.2	16.0	19.4	1.86	0.14	0.34	0.16
Caproate	9.41	7.88	7.34	7.28	1.246	0.25	0.47	0.51
Acetate/Propionate	3.69	3.51	2.65	2.74	0.211	0.005	0.84	0.55
Acetate+Butyrate/Propionate	4.31	4.16	3.21	3.37	0.308	0.022	0.98	0.63

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.