A METHOD FOR OBTAINING AND STORING UNIFORM SILAGE FOR FEEDING EXPERIMENTS

96 silages selected from farms across Northern Ireland to cover wide r anges of pH values, and dry matter, ammonia and metabolisable energy c oncentrations, were individually mixed and stored in evacuated polythe ne bags for 18 +/- 2.1 days before being used in a major voluntary int ake study. Composite samples, taken both before and after storage, wer e analyzed for dry matter content, nitrogenous, volatile and carbohydr ate constituents, gross energy concentration, buffering capacity, pH a nd osmolality. There were no significant changes in the concentrations of dry matter or volatile constituents following storage. When expres sed on a fresh basis, total and acid insoluble nitrogen concentrations , water soluble carbohydrate and gross energy concentrations were sign ificantly (P < 0.05) lower after storage, but in all cases the absolut e differences in concentration were small. The significance of the cha nge in total and acid insoluble nitrogen, and water soluble carbohydra te concentrations was increased (P < 0.01) when results were expressed on a dry matter basis. Gross energy and neutral detergent fibre conce ntrations showed a significant decrease (P < 0.05), and acid detergent fibre concentration a significant increase (P < 0.05) after storage, when results were expressed on a dry matter basis. The changes normall y associated with aerobic deterioration, such as decreases in lactic a nd acetic acids, total alcohol, and soluble carbohydrate concentration s, and an increase in ammonia nitrogen level did not occur during the course of the study, neither was there any visual evidence of mould gr owth. These factors indicate that the methodology adopted for the pres ervation effectively maintained anaerobic conditions, and offers consi derable potential for use in detailed feeding experiments.