The effects of a barley beef diet without (control) and with a yeast culture (YC) on rumen fermentation, in vivo diet digestibility, nitrogen retention, live-weight gain and food intake were evaluated using 13 Limousin × British Friesian bulls per treatment. The YC was composed of the yeast species Saccharomyces cerevisiae and its growth medium dried in such a manner that it maintained its fermentative capacity. The addition of YC significantly increased the concentration of acetate (P < 0·05) while propionate concentration tended to be higher for bulls given YC (P > 0·05). The acetate: propionate ratio remained unchanged. Concentration of total volatile fatty acid (VFA) was significantly higher in YC bulls compared with control bulls (P < 0·05). The in vitro studies using the Menke gas test confirmed these findings. Mean in vitro gas production in bulls receiving YC was lower than that in the controls (P < 0·05) and methane production was significantly reduced by the addition of YC after 12h (P < 0·01). Ruminal ammonia concentrations were not affected by treatment but ruminal pH was significantly depressed by the addition of YC (P < 0·05).Apparent digestibility of dry matter, organic matter, crude protein and neutral-detergent fibre were unaffected by treatment but tended to be higher with the control diet. Nitrogen retention was not affected by the addition of YC and mean values for allantoin excretion and plasma urea were similar.In a 28-week feeding trial, dry-matter intake was significantly greater for bulls given YC (5·55 kg/day) than for control bulls (5·32 kg/day, P < 0·05) but average daily gain, 1·55 and 1·58 kg/day for control and YC respectively, and food conversion efficiency were not improved significantly by YC (P > 0·05).

El Hassan, S. M., Newbold, C. J., Edwards, I. E., Topps, J. H., Wallace, R. J. (1996). Effect of yeast culture on rumen fermentation, microbial protein flow from the rumen and live-weight gain in bulls given high cereal diets. Animal Science, 62 (1), 43-48.Four groups each of eight Limousin X Friesian bulls, average weight 344 kg, were offered individually ad libitum diets comprising: 920 g rolled barley, 50 g cane molasses, 15 g urea and 15 g minerals/vitamins mix per kg or 867 . 5 g rolled barley, 50 g cane molasses, 7 . 5 g urea, 60 g soya-bean meal and 15 g minerals/vitamins mix per kg, plus or minus yeast culture (YC, 1 . 5 kg/t) (all weights fresh weights), until slaughter (460 kg). Rumen samples were obtained by stomach tube. YC decreased rumen ammonia concentrations (116 . 7, 56 . 0, 74 . 3, 45 . 7 (s.e.d. 19 . 40) mg/l for barley/urea, barley/urea/YC, barley/soya-bean meal and barley/soya-bean meal/YC, respectively). This was associated with increases (P <0 . 05) in both the total number of bacteria (2 . 3, 4 . 2, 3 . 5, 6 . 8 (s.e.d. 1 . 06) X 10(9) per ml, respectively) and the protein content of rumen fluid (7 . 7, 9 . 6, 8 . 7, 9 . 0 (s.e.d. 0 . 59) g/l, respectively). However, the flow of microbial protein from the rumen as estimated from the appearance of purine derivatives in the urine was unaffected (131, 130, 129, 147 (s.e.d. 12 . 6) g N per day, respectively). Thus although the animals responded to the undegradable rumen protein supplied by the soya-bean meal there was no significant response in live-weight gain with YC (1 . 28, 1 . 31, 1 . 42, 1 . 48 (s.e.d. 0 . 081) kg/day, respectively).Peer reviewe

1. Herbage was ensiled, fresh at 17% DM or wilted to 32% DM, with and without the addition of formic acid (19-2 kg/tonne DM). The silages were fed individually ad libitum to 36 fifteen-month-old British Friesian steers of about 280 kg initial live weight (nine animals per treatment). 2. Wilting and the application of formic acid both inhibited fermentation, resulting in silages with higher levels of water-soluble carbohydrates, lower concentrations of volatile nitrogen and lower organic acid contents. 3. There were no significant dry matter x formic acid interactions in dry-matter intake or daily live-weight gain. 4. Treatment with formic acid did not enhance significantly either dry-matter intake or daily live-weight gain. Furthermore, it had little effect on digestibility, nitrogen retention or metabolizable energy (ME) concentration. 5. Wilting before ensiling increased dry-matter intake from 5-0 to 8-3 kg/head per day with consequent marked increases in ME intake, nitrogen retention and live-weight gain. Wilting, however, had little effect on digestibility, ME concentration, or the efficiency with which dietary nitrogen intake was retained.

Supplementation with Yea-sacc - yeast (Saccharomyces cerivisiae ‘1026’) and its growth medium - has been found by several workers to alter rumen fermentation patterns, increase milk yield and growth rate in dairy cows and calves. This experiment investigated the effect of inclusion in the diet of intensively fed bulls on rumen fermentation and animal performance.Twenty-six Limousin x Friesian bulls reared to 3 months of age on a common diet were allocated to treatment on the basis of liveweight and previous growth rate at an average liveweight of 133 kg.The Treatments were Control ‘C” and Yea-sacc ‘YC’ - the control diet supplemented with Yea-sacc. (Alltech Inc. USA) at 1.5 kg/tonne of fresh feed. The diet was a mixture of barley and soyabean meal (Tables 1 & 2) with the inclusions of the latter reduced at 159 days. Mineral and vitamin supplements were included together with molasses to bind the ingredients.

No abstract