Table 8.

Effects of pre-grazing sward height and energy supplementation level on rumen fluid pH, N-NH₃, VFA, and plasma glucose concentration of Nellore steers grazing Marandu Palisadegrass (B. brizantha [Hochst. Ex A. Rich.] Stapf. cv. Marandu) during the rainy season

	Pre-grazing sward height, cm		Supplememntation1, % BW			P-value
Item2	25	35	0	0.3	SEM	Sward height	Supplementation	Interaction
Ruminal pH	6.39	6.52	6.46	6.44	0.14	<0.001	0.57	0.34
Total VFA, mM	145	146	144	146	7.05	0.32	0.82	0.77
VFA, mol/100 mol
Acetate	69.8	70.5	71.1	69.4	0.90	0.70	<0.001	0.98
Propionate	19.4	19.2	18.5	20.2	0.53	0.95	<0.001	0.51
Butyrate	11.0	10.3	10.4	10.7	0.63	0.22	0.57	0.96
Acetate:propionate ratio	3.75	3.74	3.95	3.51	0.13	0.74	<0.001	0.40
N-NH3, mg/dL	11.2	9.77	11.3	9.70	1.10	0.02	0.01	0.33
Plasma glucose, mg/dL	51.8	53.2	54.3	53.9	1.89	0.98	0.95	0.65

¹Supplementation levels were 0% or 0.3% BW of ground corn on an as-fed basis.

²The experiment lasted 64 d and consisted of four experimental periods of 16 d each. Rumen fluid (approximately 100 mL) was collected at 0, 2, 4, 6, and 8 h after supplement feeding with the use of a sampling probe (Danes et al., 2013) on day 16. Blood samples were collected on day 15 of the experimental period 3 h after feeding the supplement, from the coccygeal vein of each steer, directly into a lithium heparin-coated vacutainer.