The buffering constituents of herbage and of silage

Abstract

The buffering capacity values of several herbage species and of silage made from this herbage, and the contributions of plant constituents to this buffering, between pH 4 and 6, were determined, and found to vary with the herbage species; values in the silages were normally two to three times greater than those in the plant materials. The anion fraction of the plant materials accounted for 68–80% of the total buffering capacity, and for 73–88% in the silages. Buffering caused by plant proteins was estimated to be 10–20% of the total buffering capacity. The buffering capacity of wilted red clover (Trifolium pratense) was 18% lower than that of fresh red clover, and the total organic acid content of wilted clover was also lower than that in fresh clover. The organic acids were responsible for most of the buffering effect in herbages and silages. In Italian ryegrass (Lolium multiflorum), the main buffers were malate and citrate, but, in red clover, glycerate and malate were the main buffers. The clovers studied contained a high level of glycerate (4% of dry matter). During ensilage, malate, citrate and glycerate were extensively broken down. The increased buffering capacity during ensilage was caused mainly by the formation of lactates and acetates.