Effects of live and autoclaved yeast cultures on ruminal fermentation <i>in vitro</i>

Abstract

The objective of this study is to determine whether a yeast culture of Saccharomyces cerevisiae has an effect on parameters of ruminal fermentation and whether the potential positive effects of yeast culture are associated with the yeast's viability. For this purpose, live and autoclaved yeast cultures were tested simultaneously in the rumen simulation technique (Rusitec). Each fermentation vessel received daily 9 g of a basal diet consisting 5 g meadow hay and 4 g pelleted concentrate.Yeast preparations (1.5 g/day) were added with the feed. Compared to the control vessels, the pH of ruminal fl uid was signifi cantly (P<0.05) lower in the vessels supplemented with autoclaved yeast culture. Live yeast culture had no effect on the pH. Both yeast preparations resulted in a signifi cant increase (P<0.05) in NH 3 -N concentration, total and individual short-chain fatty acid (SCFA) production except valerate. The increase in NH 3 -N concentration and propionate production was signifi cantly higher (P<0.05) in the vessels supplemented with live yeast culture than that with autoclaved yeast culture. Also, the ratio of acetate to propionate was signifi cantly lower (P<0.05) by live yeast culture, when compared with the control vessels. Organic matter digestibility was not signifi cantly affected by both yeast preparations. In conclusion, these results indicated that the addition of live and autoclaved yeast cultures stimulated ruminal fermentation but this effect was more pronounced with live yeast culture.

The effects of active dried and killed dried yeast on subacute ruminal acidosis, ruminal fermentation, and nutrient digestibility in beef heifers1

“…The effects observed on NH 3 -N with both ADY and KDY are consistent with previous in vitro studies using either ADY (Miller-Webster et al, 2002) or both ADY and KDY (Oeztuerk, 2009). However, most of the previous animal studies have shown either no effects (Newbold et al, 1996;Yoon and Stern, 1996;Thrune et al, 2009) or reduced ruminal NH 3 -N concentration (Erasmus et al, 1992;Lascano and Heinrichs, 2007) in response to yeast supplementation.…”

“…However, most of the previous animal studies have shown either no effects (Newbold et al, 1996;Yoon and Stern, 1996;Thrune et al, 2009) or reduced ruminal NH 3 -N concentration (Erasmus et al, 1992;Lascano and Heinrichs, 2007) in response to yeast supplementation. The effects on NH 3 -N in various in vitro studies (Miller-Webster et al, 2002;Oeztuerk, 2009) were attributed to the microbial degradation of yeast cells because of their high protein content. However, this explanation might not be pertinent to the present study because the level of yeast supplementation was lower (0.35 mg/g of DMI) as compared to previous in vitro studies (Miller-Webster et al, 2002;Oeztuerk, 2009) and microbial degradation of yeast cells supplemented at lower levels would not increase NH 3 -N concentration.…”

“…The effects on NH 3 -N in various in vitro studies (Miller-Webster et al, 2002;Oeztuerk, 2009) were attributed to the microbial degradation of yeast cells because of their high protein content. However, this explanation might not be pertinent to the present study because the level of yeast supplementation was lower (0.35 mg/g of DMI) as compared to previous in vitro studies (Miller-Webster et al, 2002;Oeztuerk, 2009) and microbial degradation of yeast cells supplemented at lower levels would not increase NH 3 -N concentration.…”

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

“…On the other hand, propionate is energetically more efficient because its production is in indirect competition with methanogens for metabolic hydrogen (Hegarty 1999). The effects observed on NH 3 -N with hydrolysed yeast products are consistent with previous in vitro and in vivo experiments using inactivated yeast products (Oeztuerk et al 2005;Oeztuerk 2009;Vyas et al 2014). 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.…”

Screening of live yeast and yeast derivatives for their impact of strain and dose on in vitro ruminal fermentation and microbial profiles with varying media pH levels in high‐forage beef cattle diet

“…Yeast derivatives were also effective in the stimulation of rumen fermentation, and are considered to have a prebiotic effect . Unlike LY, the main role of YD is as a nutritional provider for microbes to stimulate ruminal fermentation.…”