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 lo 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 7 3 4 8 % 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 (Tri/blium 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.
The determination of dry matter in silages by distillation with toluene gives satisfactory results when an allowance is made for volatiles present in the aqueous distillate. A simple correction procedure, involving a single titration of the distillate, has been developed, and the method is considered suitable for routine purposes.
In this review the major nitrogenous components of herbage have been identified and the effects of both plant and microbial enzyme activity on these components during the ensilage process have been described. In particular, the specific effects of the lactic acid bacteria and clostridia on amino acid degradation and the end products of such microbial activity are summarised. The effect of formaldehyde in preventing proteolysis is also discussed.
DEWAR et a1.-HEMICELLULOSE HYDROLYSIS I N SILAGE 41 1pinned discs was much the finer, it is noteworthy that in both cases discontinuities occur a t approximately the sizes mentioned above, where the nature of the particles changes. Thus, although it is possible that some air-classified fractions may exhibit a log normal size distribution, there is little to be gained by plotting results for samples covering a wide particle size range in this way.The production of reducing sugars, resulting from the incubation of a hemicellulose prepared from Lolium pevenne (perennial ryegrass), with enzymes extracted from Loliuin perenne, Lolium italicnnz (Italian ryegrass) and Dactylis glomevata (cocksfoot) was measured over a range of temperature, pH and time. Each of the three enzymes had an optimum pH of 6 but the optimum temperature ranged from 30" to 43". There was a significant interaction between high temperature and low pH, both tending to suppress enzyme activity. Appreciable amounts of reducing sugars were also produced from hemicelluloses by acid hydrolysis (pH 4) over a go-day period.Attempts to grow a number of strains of lactic acid bacteria using hemicellulose as an energy source were unsuccessful. The importance of these findings on the ensilage process is discussed.
The atten$ted removal of extraraeous Ketolzic materialsSuch materials causing variation in the conversion factor may possibly be removed if the extract is percolated through activated alumina prior to analysis (after the method of Brown et aZ.12). This technique has been satisfactorily employed in the direct spectrophotometric method of a n a l y~i s .~ Preliminary investigation indicated that deviation between conversion factors for distilled and normal extract was reduced by treatment with alumina to 5%. This work, however, has not been continued since it renders the method cumbersome and shows no great improvement over the normal analysis involving the chromatographic separation of the pyrethrin z,+dinitrophenylhydrazone derivatives. Conclusionsin formulations containing synergists and emulsifying agents. duplicate analyses of the formulation and reagent blank takes from I-I* h.
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