EFFECT OF YEAST CULTURE AND PHENOLIC-ACIDS ON THE PHYSIOLOGY OF RUMENFERMENTATION DETERMINED IN-VITRO

The effect of p-hydroxybenzoic acid (HBA), syringic acid (SYA) and yea st culture (YS) on rumen fermentation in vitro has been investigated. Meadow hay was used as a substrate and rumen fluid as an inocula. The yeast culture Levucel contained 5x10(8) yeast cells Saccharomyces cere visiae per 1 g of dry matter and was used in the amount of 0.5 g/l of the medium. The following combinations of additives were used: hay wit hout additive, hay + YS, hay with 1, 5 or 10 mmol HBA or SYA, and hay + YS with 1, 5 or 10 mmol HBA or SYA. The test tubes were incubated fo r 96 hours at 39 degrees C. The results showed that 1 mmol HBA had a s ignificant effect on yeast efficacy. This was manifested in the increa sed degradability of hay dry matter (P<0.05) and enhanced total gas pr oduction (P<0.05). SYA in the same amount combined with yeast had a si milar effect on gas production (P<0.05), but hay dry matter degradabil ity was not affected. The results showed a slight effect of phenolic a cids and yeast culture on hay rumen fermentation in vitro.