Table 3.

Effects of forage to concentrate ratio and dietary sunflower oil supplement on milk yield, and energy and nitrogen partitioning in lactating dairy cows

	Treatment1					P-value3
Item, unit	L	LSO	H	HSO	SEM2	FC	SO	FC×SO
Milk yield, kg/d4	26.7	25.7	29.7	28.9	2.50	0.12	0.60	0.97
Energy corrected milk, kg/d	26.1	25.5	30.0	25.1	1.99	0.18	0.056	0.10
Fat, g/d	1,050	1,076	1,230	838	84.6	0.55	0.007	0.003
Protein, g/d	901	823	1013	1012	60.9	0.005	0.42	0.38
Lactose, g/d	1161	1122	1292	1257	115	0.14	0.64	1.00
Energy
GE intake, MJ/d	353	365	438	417	16.0	0.003	0.78	0.30
Energy output/energy intake, %
Feces	33.1	31.7	26.8	30.1	1.10	0.007	0.36	0.053
Urine	4.14	3.77	3.10	2.80	0.175	0.001	0.10	0.85
Methane	7.20	5.12	4.90	4.36	0.304	0.002	0.005	0.044
Milk	23.3	22.1	21.5	18.7	1.59	0.010	0.030	0.31
ME intake/GE intake	55.0	59.0	65.0	62.6	1.26	0.001	0.54	0.034
Milk energy/ME intake	42.3	37.4	33.0	29.8	2.47	0.002	0.037	0.59
Nitrogen (N)
N intake, g/d	464	452	558	496	19.6	0.009	0.09	0.22
N output/N intake, %
Feces	32.5	30.8	31.1	30.3	1.00	0.38	0.26	0.72
Urine	36.9	37.1	30.0	31.0	2.60	0.022	0.78	0.86
Milk	30.5	28.7	29.3	33.0	1.60	0.066	0.19	0.006
N balance, g/d	1.50	16.1	53.6	29.3	8.62	0.009	0.59	0.065

¹Refers to diets based on low (0.35) or high (0.65) concentrate ratio supplemented with 0.0 (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.

⁴Milk yield data is reprinted from Ventto et al. (2017), The Nutrition Society, published by Cambridge University Press.