Vitamin D2 production and in vitro ruminal degradation of UV-B irradiated vitamin D enriched yeast in Thai native cattle

Abstract

The purposes of this study were to investigate the optimum UV-B irradiation time needed to produce vitamin D enriched yeast and to promote in vitro ruminal degradation of UV-B irradiated vitamin D enriched yeast in Thai native cattle. Baker’s yeast and S. cerevisiae were irradiated at 0, 2, 4, 8, 10, 12, 16 and 24 hours. The UV-B irradiation of both yeast strains could significantly enhance vitamin D2 to the highest amount at 16 hours. The corn stover and TMR were studied for determination of in vitro ruminal degradation, included three treatments that involved each type of feed, namely feedstuff without supplementation, feedstuff with live yeast supplementation and feedstuff with UV-B irradiated vitamin D enriched yeast. Gas production data of the live yeast group and the UV-B irradiated vitamin D enriched yeast supplementation group, were significantly higher than those of the control groups for both types of feedstuffs. The vitamin D content of the vitamin D enriched yeast supplementation groups were not significantly different from those of the groups subjected to an initial incubation period (10.98 vs. 14.43μg, respectively). Therefore, after a period of irradiation of 16 hours, the two yeasts strain produced the highest vitamin D2 content, while Baker’s yeast produced vitamin D2 at higher amounts than S. cerevisiae. Notably, UV-B irradiated vitamin D enriched yeast improved the in vitro ruminal degradation, while also preventing a loss in the amount of vitamin D that was degraded by the rumen microorganisms.