Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2001
Publication Date: 8/1/2001
Technical Abstract: Research has shown that feeding Saccharmoyces cervisiae (SC) to growing steers increases ruminal fluid pH and digestibility of certain nutrients. Therefore, the objective of this study was to determine the in situ dry matter disappearance (DMD) of grain and hay sources, and ruminal fluid pH in the presence of different yeast strains. Three ruminally-cannulated cows were individually fed either no yeast, 10 g of SC47 (BIOSAF; 8x10**9 CFU/g), or 5.3 g of P7 (1.5x10**10 CFU/g) daily in a 3 X 3 Latin Square (LS) design. Each period of the LS consisted of a 12-d adaptation and 3-d data collection. Cows were fed 7.7 kg of a 90% concentrate diet using electronic head gates. On d 13, 5 g of steam-flaked corn grain, wheat grain, milo, alfalfa hay, and low and high quality sorghum hay was introduced into the rumen contents using in situ digestion bags at 0, 24, 36, 40, 44, and 48 h (3 replicates/time). At 48 h, bags were removed and washed with hot water. Bags were dried at 60 C and weighed to determine DMD. On d 15, ruminal fluid pH was measured at 0, 2, 4, 6, and 8 h after feeding. Wheat grain was the most rapidly digested followed by corn grain and then milo. Alfalfa hay was the most rapidly digested among the forages, with both sorghum hays having similar (P > 0.10) DMD. There was no effect (P > 0.10) of yeast cultures on the rate or extent of in situ DMD of grains or hays. The regression of indigestibility (1-DMD) did not indicate that yeast strains used in this study increased the rate or extent of DMD of grains or hays. Ruminal fluid pH (6.45, 6.47, and 6.30) was similar (P=0.16) when cows were fed the control, P7, and SC47 diets, respectively. These data suggest that there was no effect of the yeast strains tested on the DMD of the grains or hays and on ruminal fluid pH.