Table 3.

Effects of moisture addition to grain (tempering) prior to steam conditioning on the production of VFAs by in vitro cultures of mixed ruminal microbes fed steam-flaked corn as substrate

	Tempering moisture, %1				P-value
VFA, mmoles/g substrate DM2	0	3	6	SEM	Linear	Quadratic
Acetate	1.60	1.54	1.60	0.063	0.91	0.04
Propionate	1.85	1.78	1.84	0.063	0.71	0.07
Acetate:propionate	0.87	0.87	0.88	0.048	0.31	0.50
Butyrate	0.52	0.51	0.52	0.067	0.72	0.60
Isobutyrate	0.003	0.002	0.002	0.0021	0.59	0.97
Valerate	0.063	0.063	0.064	0.0116	0.68	0.80
Isovalerate	0.006	0.006	0.005	0.0026	0.29	0.71
Total	4.05	3.90	4.02	0.082	0.79	0.08

¹Performed by adding water (w/w) with whole grains into glass jars. Jars were placed on rollers and mixed 60 min prior to steam conditioning.

²VFAs were measured by gas chromatography following 24-h incubation of cultures containing 3 g (DM) flaked corn as substrate, 10 mL ruminal fluid inoculum, and 140 mL McDougall’s Buffer at 39 °C. Initial incubation was repeated with two replicates per sample (90 samples, 180 observations, 60 per treatment).