Table 1.

Effect of addition of chestnut tannin (CWT) or Stevia rebaudiana Bertoni (SB) extracts to a control (CTR) substrate (corn meal) on the pH, ammonia and VFA of fermentation fluid and gas yield measured at 24 h (Exp. 1).

Item	Treatment			SEM
	CTR	CWT	SB
24-h gas yield, mL	1,621	1,584	1,648	23.9
pH	7.26	7.25	7.32	0.027
Ammonia, mg/dL	27.9a	24.8b	27.5a	0.58
Total VFA, mmol/L	115.4	117.7	121.4	1.49
VFA, mol/100 mL
Acetate	55.46	54.87	54.75	0.299
Propionate	26.16	27.05	27.55	0.427
Iso-butyrate	1.34	1.24	1.26	0.138
Butyrate	12.98	12.89	12.46	0.259
Iso-valerate	2.23	2.08	2.34	0.055
Valerate	1.85	1.88	1.64	0.240
Acetate:Propionate ratio	2.17	2.06	2.01	0.049

SEM = standard error of the means.

^a,b Within rows, means without a common superscript differ (P < 0.05).