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Influence of combined yeast culture and enzymatically hydrolyzed yeast on in vitro ruminal fermentation in contrasting feed substrates.

BACKGROUND
Feed additives such as live yeast cultures have increasingly been used in ruminant feeds to improve animal performance and feeding efficiency. However, it is not clear how inactive combined yeast cultures affect ruminal gas production, fermentation kinetics and efficiency. Therefore, this study was done to determine the influence of incubating different substrates with a combined yeast culture + enzymatically hydrolyzed yeast (YC + EHY) on in vitro ruminal gas production, fermentation kinetics and metabolizable energy. Six contrasting substrates (Trichantera gigantea and Glircidia sepium leaves, Brachiaria hybrid (CV Mulato II) leaf + stem and leaf only, Cynodon nlemfuensis and a commercial concentrate dairy feed) were incubated with and without YC + EHY in buffered rumen fluid and gas production measured at 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48 and 72 h post incubation.


RESULTS
In vitro fermentation parameters (a, b, a + b and c) were unaffected by YC + EHY except for the lag phase in T. gigantea that reduced by 31.3% when it was incubated with YC + EHY. Supplementation with YC + EHY also did not affect ME, 72 h OMD, 24 h gas and CH4 production within substrate. However, cumulative gas and methane production at peak fermentation in the commercial concentrate feed was reduced by 20% when incubated with YC + EHY.


CONCLUSION
It was concluded that YC + EHY has potential to improve microbial colonization of T. gigantean substrates and reduce gas and methane production at peak fermentation in commercial concentrate feeds. This article is protected by copyright. All rights reserved.