The supplementation of ruminant diets with exogenous cellulolytic enzymes can improve their digestibility and feeding value. The objective of this study was to determine the effect of supplementing roughage (rice straw) and concentrate with inoculants containing four fungal strains (Pleurotus ostreatus, Phanerochaete chrysosporium, Trichoderma reesei and Trichoderma viride) and four bacterial strains (Paenibacillus polymyxa, Bacillus megaterium, Bacillus circulans and Bacillus subtilis), given separately or as a mixture, as a source of exogenous cellulolytic enzymes, on basic rumen parameters in vitro, including digestibility and methane production. A batch culture trial was used to select the best supplements, and a long-term rumen simulation technique (RUSITEC) was used to evaluate the effects of P. chrysosporium, B. subtilis, and a 1 : 1 mixture of these two on dietary component digestibility and fermentation parameters. In the batch culture evaluation, there were significant increases in the organic matter (OM) digestibility, the total gas production expressed as ml/g of dry matter, the OM, the neutral detergent fibre (NDF) and the acid detergent fibre (ADF) of the supplemented rations, as compared to the control, excluding the rations supplemented with T. viride and B. circulans. In the RUSITEC, the ration supplemented with mixed inoculants showed significantly higher digestibility of crude protein, ether extract, NDF and ADF than did the ration supplemented with the P. chrysosporium and B. subtilis inoculants. It can be concluded that the simultaneous use of fungal and bacterial exogenous cellulases on rice straw roughage improves its digestibility, without negative effects on other rumen parameters.

Four silages were prepared from perennial ryegrass swards at each of first (primary growth), second (first regrowth) and third (second regrowth) harvests during the 1993 growing season. At each harvest the four silages included two unwilted (without and with inoculant at 2·4 l/t) and two wilted (without and with inoculant at 24 l/t). The four silages within a single harvest, were offered as the total diet at maintenance levels to 12 wether sheep for 3 weeks to determine nutrient apparent digestibilities. They were also given to 12 lactating dairy coivs together with a concentrate supplement, in a three-period change-over study with experimental periods of 8-weeks duration, to examine dry matter (DM) apparent digestibility and utilization of nitrogen (N) and energy in the diets.

Inoculation tended to improve silage fermentation with on average lower pH and ammonia-N/total-N across the three harvests, while wilting of grass prior to ensiling significantly increased silage pH fP < 0·001) and ammonia-N/total-N (P < 0·001). Neither inoculation nor wilting had any significant effect on mean nutrient apparent digestibilities, assessed through sheep, across the three harvests. However, at the second harvest inoculation significantly reduced apparent digestibilities of DM (P < 0·001) and N (P < 0·001). At this harvest, wilting also significantly decreased apparent digestibilities of DM (P<0·05) and N (P <0·01), but significantly increased apparent digestibilities of DM (P < 0·05), energy (P < 0·001) and N (F < 0·05) at the third harvest. When the silages were offered as mixed diets to dairy cattle, neither inoculation nor wilting had significant effects on digestibilities of DM, N and energy at any of the three harvests, except for wilting which significantly decreased DM apparent digestibilities (P < 0·05) at the second harvest. However, the mean apparent digestibilities of DM (P < 0·01), N (P < 0·05) and energy (P < 0·01) across the three harvests were significantly lower following wilting, and N apparent digestibility (P < 0·05) was significantly higher following inoculation. The calorimetric data indicated that inoculaton had no significant effects on either methane energy output or heat production. Wilting also had no significant effect on methane energy output, but significantly increased daily heat production (P<0·05) at the first harvest. The efficiencies of metabolizable energy utilization for lactation (k1) were similar between the four silages at each of the first and second harvests, with the average being 0·50. The results of the present study indicated that inoculation tended to improve silage fermentation and significantly increased mean N apparent digestibility of mixed diets across the three harvests, while wilting significantly reduced mean DM, N and energy apparent digestibilities of mixed diets. Neither inoculation nor wilting had significant effects on Rvalue.

Four silages (unwilted with and without inoculant, and wilted with and without inoculant) were prepared from perennial ryegrass swards at each of three harvests over the growing season. The four silages from each of the first (primary growth), second (first regrowth) and third (second regrowth) harvests were offered ad libitum to 48 dairy cows during periods 2, 1 and 3 respectively, in a two (control and additive) × two (unwilted and wilted) × three (harvest (period)) change-over design experiment with 8-week experimental periods. The animals also received a concentrate supplement at 7·0, 6·1 and 5·2 kg dry matter (DM) per day in the first, second and third periods respectively. The supplement was based on barley, molasses and soya-bean meal.

There were significant interactions between inoculation and wilting across the three harvests on silage DM intake (F<0-01), milk yield (P<0·05), and outputs of fat (P<0·01) and protein (P<0·05). Inoculation had no significant effects on silage intake and milk production across the unwilted and wilted silages. However, within the unwilted silages, inoculation significantly increased silage DM intake by 0·46 kg/day (P < 0·05) and fat yield by 0·032 kg/day (P<0·05). In contrast, within the wilted silages inoculation significantly reduced fat yield by 0·030 kg/day (P < 0·05). Wilting of grass prior to ensiling significantly increased silage DM intake by 0·73 kg/day (P <0·001), milk yield by 0·42 kg/day (P<0·05), fat yield by 0·053 kg/day (P < 0·001) and protein yield by 0·047 kg/day (P < 0·001) across the inoculant-treated and untreated silages. The effects however were mainly derived from the untreated silages as within the inoculant-treated materials the differences in silage intake and milk yield were not significant between unwilted and wilted treatments. The results of the current experiment indicate that wilting with no additive significantly improved silage intake and milk production, but otherwise the improvement was reduced with wilting following inoculation. Inoculation significantly increased silage intake and fat yield when used with the unwilted grass, but it significantly reduced fat yield when used with the wilted grass.