Live yeast cultures and yeast hydrolyzates can be used as rumen fermentation modifiers, but their effects and mode of action are different. Whereas the effects of live yeast cultures on rumen fermentation are well documented, yeast hydrolyzates have received much less attention. The influence of a yeast hydrolyzate from Saccharomyces cerevisiae, obtained after ethanol production from sugarcane (YHS), on in vitro rumen fermentation was investigated using both batch cultures and Rusitec fermenters inoculated with ruminal fluid from sheep. Batch cultures (300 mg dry matter (DM)) with two mixed diets (AHC, 0.5:0.5 alfalfa hayxoncentrate; BSC, 0.15:0.85 barley strawxoncentrate) as substrate were supplemented with increasing doses of YHS (0, 3.3, 6.7, 10.0 and 13.3 ml/1) and incubated for 16.5 h at 39 °C. Supplementation of increasing amounts of YHS to AHC-cultures increased (P < 0.05) linearly total volatile fatty acid (VFA) production and butyrate molar proportion, and decreased (P < 0.001) acetate proportion and acetate:propionate ratio. In contrast, only subtle effects of YHS on NH 3-N concentrations and molar proportions of isovalerate and caproate were observed for the BSC diet. Longer-term effects of YHS supplementation on rumen fermentation of AHC diet were investigated using four Rusitec fermenters in a cross-over experimental design with two 14-day incubation periods. Fermenters were given daily 30 g of diet DM, and in each period half of them were supplemented daily with 5 ml of YHS (10.0 ml/1) Supplementing with YHS did not affect (P > 0.05) total VFA production, lactate concentrations, DM and aNDFom disappearance or enzymatic activities (amylase, xylanase and carboxymethylcellulase). Compared with the unsupplemented fermenters, YHS treatment increased (P < 0.001) NH 3-N concentrations and molar proportions of propionate and butyrate at the expense of acetate, and decreased (P < 0.001) acetate:propionate ratio. In addition, YHS supplementation tended (P < 0.07) to reduce CH 4 /total VFA ratio and to increase microbial growth in the liquid phase of the fermenters. The automated ribosomal intergenic spacer analysis (ARISA) of samples taken on days 3, 8 and 14 of incubation from solid and liquid content of fermenters revealed that YHS supplementation increased (P < 0.02) bacterial Abbreviations: ADFom, acid detergent fiber expressed exclusive of residual ash; AFOM, apparently fermented OM; aNDFom, neutral detergent fiber with heat-stable amylase and expressed exclusive of residual ash; ARISA, automated ribosomal intergenic spacer analysis; CP, crude protein; BSC, 15:85 barley straw:concentrate; AHC, 50:50 alfalfa hay:concentrate; OM, organic matter; VFA, volatile fatty acids; YH, yeast hydrolyzate; YHS, yeast hydrolyzate obtained from sugarcane processing diversity in the liquid phase and tended to increase {P < 0.08) it in the solid phase. The results indicate that YHS at a dose of 10 ml/1 may be a useful dietary additive for ruminants, because it promoted a shift in fermentation toward propionate production,...

The effects of three treatments of fibrolytic enzymes (cellulase from Trichoderma longibrachiatum (CEL), xylanase from rumen micro-organisms (XYL) and a 1:1 mixture of CEL and XYL (MIX) on the in vitro fermentation of two samples of Pennisetum clandestinum (P1 and P2), two samples of Dichanthium aristatum (D1 and D2) and one sample of each Acacia decurrens and Acacia mangium (A1 and A2) were investigated. The first experiment compared the effects of two methods of applying the enzymes to forages, either at the time of incubation or 24 h before, on the in vitro gas production. In general, the 24 h pre-treatment resulted in higher values of gas production rate, and this application method was chosen for a second study investigating the effects of enzymes on chemical composition and in vitro fermentation of forages. The pre-treatment with CEL for 24 h reduced (p < 0.05) the content of neutral detergent fibre (NDF) of P1, P2, D1 and D2, and that of MIX reduced the NDF content of P1 and D1, but XYL had no effect on any forage. The CEL treatment increased (p < 0.05) total volatile fatty acid (VFA) production for all forages (ranging from 8.6% to 22.7%), but in general, no effects of MIX and XYL were observed. For both P. clandestinum samples, CEL treatment reduced (p < 0.05) the molar proportion of acetate and increased (p < 0.05) that of butyrate, but only subtle changes in VFA profile were observed for the rest of forages. Under the conditions of the present experiment, the treatment of tropical forages with CEL stimulated their in vitro ruminal fermentation, but XYL did not produce any positive effect. These results showed clearly that effectiveness of enzymes varied with the incubated forage and further study is warranted to investigate specific, optimal enzyme-substrate combinations.

Winter oats were grown according to European organic farming regulations in monoculture (oats) and in intercropping with bard vetch (BAV), bitter vetch (BIV) or both legumes (MIX) to evaluate the effects of intercropping on forage yield and nutritive value for ruminants. The experiment was carried out as a randomised complete block design with four replications, and whole forage samples were obtained at two harvest dates (June and July). For both harvest times, all intercrops increased (P < 0.05) forage yield compared with oats, but forage crude protein content was only increased (P < 0.05) for BAV and MIX. Compared with oats, intercropping with BAV increased (P < 0.05) in vitro rate of gas production and total volatile fatty acid production, indicating a higher rate and extent of rumen degradation of BAV forage. In contrast, BIV forage harvested in June had lower (P < 0.05) rate of gas production and total volatile fatty acid production than June oats, but in general no differences in the in vitro rumen fermentation were detected between oats and BIV samples harvested in July. The results indicate that forage yield and quality can be enhanced by intercropping oats with BAV; however, intercropping with BIV increased yield but decreased nutritive value of the forage.

Se condujo una secuencia experimental para comprobar la eficacia del contenido ruminal seco como constituyente energético-proteico en la producción de bloques nutricionales para la alimentación animal. La composición química del contenido ruminal seco mostró valores de proteína bruta cercanos al 10%, FB 42 % y FDN 87 %. Los bloques multinutricionales elaborados con 25 % del contenido ruminal seco y 10 % de urea presentaron un contenido de materia seca, cenizas, proteína bruta, materia orgánica, calcio, y magnesio de 74, 24, 25, 75, 9.16 y 0.82 % BS respectivamente con un índice de penetración cercano a 12.5 kgf/cm3 y los análisis microbiológicos mostraron la inocuidad del producto final. Las pruebas de aceptabilidad por carneros y novillas en condiciones de estabulación indicaron consumos adecuados durante el periodo de observación con cifras que se incrementaron a medida que transcurrió el tiempo de ofrecimiento. El consumo voluntario de pastos de novillas en pastoreo y la digestibilidad aparente de la materia seca de la dieta no difirieron entre los tratamientos con alimentos concentrados y los bloques multinutricionales con cifras promedio de 7 kg animal día-1. Los resultados demuestran que es posible utilizar el contenido ruminal seco como componente de los bloques multinutricionales para la alimentación animal lo que a su vez contribuye a la descontaminación ambiental.