Table 7.

Effects of increasing proportion of steam-flaked EFC in grain mixtures on the production of VFAs by in vitro cultures of mixed ruminal microorganisms fed steam-flaked corn as substrate

	Proportion of grain mixture as EFC, %						P-value
VFA, mmoles/g substrate DM1	0	25	50	75	100	SEM	Linear	Quadratic
Acetate	1.49	1.51	1.61	1.63	1.66	0.067	<0.01	0.64
Propionate	1.69	1.73	1.85	1.90	1.95	0.067	<0.01	0.83
Acetate:propionate	0.89	0.88	0.87	0.87	0.86	0.048	<0.01	0.76
Butyrate	0.53	0.48	0.52	0.51	0.54	0.067	0.21	0.06
Isobutyrate	0.004	0.000	0.003	0.003	0.002	0.0021	0.98	0.33
Valerate	0.053	0.056	0.067	0.063	0.076	0.0119	<0.01	0.61
Isovalerate	0.008	0.005	0.007	0.005	0.004	0.0027	<0.01	0.78
Total	3.77	3.78	4.05	4.12	4.24	0.097	<0.01	0.93

¹VFAs 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 (36 observations per treatment).