Effect of yeast cultures supplementation on live weight change, rumen fermentation, ciliate protozoa population, microbial hydrolytic enzymes status and slaughtering performance of growing lamb

The influence of supplementing heifer diets with <i>Saccharomyces cerevisiae</i> yeast on the activity of polysaccharidases in the rumen

“…These findings suggest a negative effect of the yeast preparation on xylanolytic activity; fungal additives can, probably, inhibit digestibility of hemicellulose in the rumen. Similar effects were found by Tripathi and Karim, (2011), when sheep were fed a diet supplemented with live yeast. In contrast to our findings, Michalet-Doreau et al (1997) showed that live S. cerevisiae increased the xylanolytic activity in the rumen of sheep.…”

“…According to these authors, higher NDF degradability increased the number and activities of fibre-degrading bacteria. In contrast, Brossard et al (2006) and Tripathi and Karim (2011) did not observe any increase in ruminal cellulolytic activity in sheep fed live S. cerevisiae. Sampling time and interaction (Trt × S) did not affect cellulolytic activity because cellulose is degraded slowly over a long time ( Table 2).…”

“…Moharrery and Asadi (2009) reported the tendency of amylolytic activity to increase when live yeast were introduced into sheep. According to Tripathi and Karim (2011), yeast culture supplementation increased the number of microbial cells in the rumen, which improved microbial enzyme status for feed fermentation. Moreover, the yeast preparation stimulated the growth of amylolytic and short-chain-polysaccharide-degrading microorganisms (Tripathi and Karim, 2011).…”

Effects of hydrolysed yeasts on ruminal fermentation in the rumen simulation technique (Rusitec)

“…The increase in NH 3 -N concentration, especially at 0.75 g, can be associated with the microbial degradation of yeast products because of their high protein content. However, most of the early animal studies have shown either no effects (Thrune et al 2009;Tripathi and Karim 2011) or reduced ruminal NH 3 -N concentrations (Lascano and Heinrichs 2007;Hristov et al 2010) in response to yeast supplementation. These differences among studies might have been due to differences in yeast preparations, type of diets and/or experimental conditions.…”

“…Certain studies have indicated that supplementation of yeast to the diet may improve feed intake (Williams et al 1991), weight gain (Tripathi and Karim 2011), digestion (Jouany et al 1998), numbers of anaerobic and cellulolytic bacteria (Newbold et al 1995), ruminal pH value (Bach et al 2007) and alter the patterns of SCFA (Marden et al 2008). However, animal responses to yeast supplementation have not been consistent.…”