Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 132-141). Also available via the Internet.

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Chopped alfalfa and chopped whole-plant corn were ensiled and the proteolytic changes which occurred during ensiling were investigated. Proteolysis was measured in terms of end-products of protein degradation and by protein isolation followed by electrophoresis. The effects of formic acid and ammonia, applied at the time of ensiling, on proteolytic changes were investigated. / Alfalfa treated with formic acid contained significantly reduced levels of NH$ sb3$-N and NPN compared to control silage; ammonia (NH$ sb3$)-treated alfalfa silage had significantly less NPN (P $<$ 0.05). After 90d of storage, formic acid-treated and NH$ sb3$-treated alfalfa silage contained lower levels of both branched and non-branched amino acids, sulfur containing, and basic amino acids compared to control silage; formic acid-treated and NH$ sb3$-treated corn silage contained lower levels of branched chain amino acids and sulfur containing amino acids after the same time period. Formic acid and ammonia were most effective in the reduction of proteolysis in alfalfa silage and corn silage, respectively. The protein ribulose 1,5-diphosphate carboxylase (RuDPCase) was depleted completely after 2d of fermentation in control silage. Conditions in NH$ sb3$-treated alfalfa silage stabilized RuDPCase during the first 24h of storage.

Alfalfa is difficult to ensile because of its low water soluble carbohydrate content, low dry matter content, and high buffering capacity. Therefore, the isolation of mutants of L. plantarum was undertaken to develop a strain(s) which could improve the fermentation of alfalfa silage when used as an inoculum. Efforts to isolate starch- or hemicellulose-utilizing strains proved unsuccessful as did the isolation of high temperature resistant mutants and oxygen resistant mutants. Mutants resistant to plumbagin (an intracellular O₂- generator) and citrate were isolated. Of these mutants, some were found to be more sensitive to cadmium than the parent strain. Though these three characteristics point to an enhanced manganese accumulation since O₂- is scavenged by manganese, citrate will chelate manganese, making it unavailable to the organism, and cadmium is transported by the manganese transport system, the rates of 54_Mn transport were no greater than the parent. When grown aerobically on a glucose-limited medium, the parent strain consumed oxygen and produced high concentrations of acetic acid and low concentrations of lactic acid. By contrast, one mutant (strain MC226), produced high concentrations of lactic acid and demonstrated low rates of O₂ consumption and low levels of acetic acid. The parent strain and two plumbagin- and citrate-resistant mutants were used to inoculate alfalfa for silage production. The inoculated silages showed a lower pH and higher titratable acidity than that of an uninoculated control. Silages inoculated with the parent strain exhibited high levels of acetic acid and low levels of lactic acid, indicative of oxygen consumption by the parent strain. Less acetic acid was evident in silages inoculated with the mutant strains. All silages contained a high level of butyric and isobutyric acids and propionic and isovaleric acids were also detected, indicative of clostridial growth. / Master of Science

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The problem of reduced appetite in ruminants fed silages persists but the factors responsible for reduced intake of silage have not been elucidated. This study was conducted with the objective of testing the hypothesis that ammonia loading in ruminants could suppress appetite. In a 5 x 5 latin square design, sheep were fed alfalfa silage (S), fresh alfalfa (FA), and FA with added equimolar amounts (450 mmol. kg$ sp{-1}$ feed DM) of NH$ sb4$Cl, NH$ sb4$HCO$ sb3$ and urea; the latter was infused directly into the rumen. The silage had a DM content of 33.1%, pH 4.4, and a lactic acid content of 4.3% of DM. Unfermented herbage had a pH of 5.5 and lactic acid content of 0.2% of DM. Digestibility of organic matter (OMD) exceeded 70% for both S and FA. Organic matter intake (OMI), digestible organic matter intake (DOMI), concentration of rumen NH$ sb3$, rumen pH, osmolality and volatile fatty acids (VFAs) did not differ (P $>$ 0.05) among treatment groups. The lack of differences among treatments may have been as a result of a failure to accentuate qualitative and quantitative differences between the FA and S and to raise ammonia in the rumen and peripheral blood to levels that could alter appetite.

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