The Effect of Yeast Culture Addition to Diets of Grass and Grass Silage on Rumen Bacterial Numbers

Abstract

It has been suggested that the mechanism by which yeast cultures (YC), based on Saccharomyces cerevisiae, improve ruminant production is by stimulating rumen fibre digestion and microbial protein flow from the rumen. Both of these effects have in turn been related to the increases in bacterial growth in the rumen observed when YC is added to the diet. However, although it is has been shown that the effectiveness of YC in improving productivity is influenced by the composition of the diet fed (Williams and Newbold, 1990), little is known about how the ability of YC to stimulate bacterial numbers in the rumen is affected by diet composition.The effect of diet on the stimulation of bacterial numbers in the rumen by YC was investigated in the rumen simulation technique (Rusitec). Grass silage was prepared from a sward of perennial rye-grass, without the use of a preservative. Fresh grass was collected from the sward prior to ensilage and stored at -20°C. Grass (5.96 g dry matter (DM) /day) and grass silage (6.54 g DM/ day) were compared alone or supplemented with 500 mg / day YC (Yea-sacc, Alltech), in triplicate, in an experiment lasting 21 days.Four rumen cannulated sheep, allowed ad lib access to grass silage, were used to investigate further the effects of YC on bacterial numbers in the rumen in vivo. The effects of YC (4 g/ day) were investigated in a 2 × 2 factorial design with 28 day periods.

Influence of Live Yeast Culture (Saccharomyces cerevisiae) on Milk Production and Composition, and Blood Biochemistry of Grazing Dairy Ewes during the Milking Period

“…Various authors found an increased number of protozoa (Arakaki et al 2000), increased live weight gain (Combellas et al 2002) and increased degradation and digestibility (Olson et al 1994a(Olson et al , 1994b. According to most authors, micro-population plays a key role in the mode of action of yeast in the rumen (Dawson 1992;Wallace and Newbold 1992;Newbold et al 1995). El Hassan et al (1994 observed that Yea Sacc 1026 stimulated the total bacterial number in a rumen-simulating fermentor (Rusitec) when the basal diet was grass and increased, but not significantly, the number of cellulolytic bacteria.…”

“…The influence of yeast supplementation on grazing animals has mainly been investigated in grazing steers (Olson et al 1994a(Olson et al , 1994bArakaki et al 2000). Much less is known about the effects of yeast supplementation on grazing dairy ewes, nevertheless in vitro trials (El Hassan et al 1994) and trials on grazing steers may give justification for investigation.…”

Influence of Live Yeast Culture on Milk Production, Composition and Some Blood Metabolites of Ossimi Ewes During the Milking Period

“…Various authors found an increased number of protozoa increased the live body weight gain (Arakaki et al 2000), (Combellas et al 2002) and increased degradation and digestibility (Olson et al 1994a(Olson et al , 1994b. (Dawson 1992;Wallace and Newbold 1992;Newbold et al 1995), showed that the micro-population plays a key role in the mode of action of yeast in the rumen El Hassan et al (1994) dound that the Yea Sacc1026 stimulated the total bacterial number in a rumensimulating fermentor when the basal diet was grass and increased, the number of cellulolytic bacteria. Subsequent increased the degradalility and digestion then fore the better performance and best daily weight gain.…”