Preparation of glycerol-enriched yeast culture and its effect on blood metabolites and ruminal fermentation in goats

PLoS One. 2014 Apr 7;9(4):e94410. doi: 10.1371/journal.pone.0094410. eCollection 2014.

Abstract

The aim of this study was to isolate a glycerol-producing yeast strain from nature to prepare glycerol-enriched yeast culture (GY), and preliminarily evaluate the effects of GY on blood metabolites and ruminal fermentation in goats. During the trial, six isolates were isolated from unprocessed honey, and only two isolates with higher glycerol yield were identified by analysis of 26S ribosomal DNA sequences. One of the two isolates was identified as Saccharomyces cerevisiae, a direct-fed microbe permitted by the FDA. This isolate was used to prepare GY. The fermentation parameters were optimized through single-factor and orthogonal design methods to maximize the glycerol yield and biomass. The final GY contained 38.7±0.6 g/L glycerol and 12.6±0.5 g/L biomass. In vivo, eight castrated male goats with ruminal fistula were used in a replicated 4×4 Latin square experiment with four consecutive periods of 15 d. Treatments were as follows: control, LGY, MGY, and HGY with 0, 100, 200, and 300 mL GY per goat per day, respectively. The GY was added in two equal portions at 08∶00 and 17∶00 through ruminal fistula. Samples of blood and ruminal fluid were collected on the last one and two days of each period, respectively. Results showed that the plasma concentrations of triglyceride and total cholesterol were not affected by the supplemented GY. Compared with the control, goats supplemented with MGY and HGY had significantly higher (P<0.05) concentrations of plasma glucose and total protein, ruminal volatile fatty acid and molar proportion of propionate, and significantly lower (P<0.05) ruminal pH and ammonia nitrogen. These parameters changed linearly with increasing GY supplementation level (P<0.05). In conclusion, GY has great potential to be developed as a feed additive with dual effects of glycerol and yeast for ruminants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Culture Techniques
  • Fermentation / drug effects*
  • Glycerol / metabolism
  • Glycerol / pharmacology*
  • Goats / blood*
  • Goats / metabolism
  • Goats / microbiology*
  • Male
  • Rumen / drug effects*
  • Rumen / metabolism*
  • Saccharomyces cerevisiae / metabolism*

Substances

  • Glycerol

Grants and funding

The project was supported by science and technology support plan project of Jiangsu Province, China (Grant number BE2011364), the Research Fund for the Doctoral Program of Higher Education of China (Grant number 20110097110014, 20120097130002), and the Priority Academic Program Development of Jiangsu Higher Education Institutions. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.