The Effect of Lactobacillus buchneri and Other Additives on the Fermentation and Aerobic Stability of Barley Silage 1

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1 J. Dairy Sci. 84: American Dairy Science Association, The Effect of Lactobacillus buchneri and Other Additives on the Fermentation and Aerobic Stability of Barley Silage 1 L. Kung, Jr. and N. K. Ranjit Delaware Agricultural Experiment Station Department of Animal & Food Science College of Agriculture and Natural Resources University of Delaware, Newark, ABSTRACT Whole-plant barley (39.4% dry matter) was treated with various chemical and biological additives to assess their effects on silage fermentation and aerobic stability. Treatments were untreated forage, forage treated with several amounts of Lactobacillus buchneri and enzymes (L. buchneri at ,5 10 5, and cfu/g of fresh forage), forage treated with an inoculant containing (Lactobacillus plantarum, Pediococcus pentosaceus, Propionibacterium freudenreichii, and enzymes), or forage treated with a buffered propionic acidbased additive (0.2% of fresh weight). Sixty-nine d after ensiling, silages treated with L. buchneri and enzymes had lower ph, but had higher concentrations of acetic and propionic acids and higher concentrations of ethanol when compared with untreated silage. Silage treated with the multistrain inoculant containing L. plantarum had lower ph and higher concentrations of lactic acid, but lower concentrations of ammonia-n, neutral detergent fiber, and acid detergent fiber than did untreated silage. The addition of the buffered propionic acid additive resulted in silage with higher concentrations of lactic and acetic acid compared with untreated silage. Numbers of yeasts in all silages were low at silo opening (less than 3.0 log cfu/g) and were numerically the lowest in silages treated with L. buchneri but only treatment with the intermediate and high level of L. buchneri improved the aerobic stability of silage. Because of the altered fermentation pattern, inoculation with L. buchneri, when applied at equal to or more than cfu/g, and enzymes improved the aerobic stability of barley silage. (Key words: Lactobacillus buchneri, barley, silage, aerobic stability) Received August 11, Accepted December 11, Corresponding author: L. Kung, Jr.; lkung@udel.edu. 1 Published as paper number in the Journal series of the Delaware Agricultural Experiment Station. Abbreviation key: BP = buffered propionic acid-based additive, IN = bacterial inoculant, LB = Lactobacillus buchneri ( cfu/g of fresh forage) and enzymes, LB5 = L. buchneri ( cfu/g) and enzymes, LB10 = L. buchneri ( cfu/g) and enzymes, WSC = watersoluble carbohydrate. INTRODUCTION Barley and other cereal grain silages are commonly harvested in the early spring followed by the planting of corn in the mid-atlantic region; but these silages spoil rapidly when exposed to air because of yeasts (Woolford et al., 1982). Lactobacillus buchneri has been used to improve the aerobic stability of corn silages (Driehuis et al., 1999; Muck, 1996; Ranjit et al., 1999), but to our knowledge has not been evaluated in barley silages. Oude Elferink et al. (1999) reported that the addition of L. buchneri to forage at the time of ensiling improved aerobic stability by fermenting lactic acid to acetic acid and 1,2 propanediol. Although heterolactic fermentation is usually deemed as undesirable compared with a homolactic fermentation (McDonald et al., 1991), improvements in aerobic stability during prolonged storage and feeding may be beneficial, thus making small losses of DM incurred during an initial fermentation less important. In previous research (Ranjit and Kung, 2000), we reported that an application rate of L. buchneri at cfu/g of fresh forage (but not cfu/g) increased the acetic acid concentration and subsequent aerobic stability of corn silage. The current study was designed to establish an appropriate dose of L. buchneri required to improve the aerobic stability of barley silage. The effects of varying doses of L. buchneri were also compared with a commercial inoculant (containing homolactic bacteria, propionic acid-producing bacteria, and enzymes) and a buffered propionic acid-based product. MATERIALS AND METHODS Whole plant barley interseeded with hairy vetch (about 5% of the DM) was harvested with a mower- 1149

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6 1154 KUNG AND RANJIT tions of ethanol, greater numbers of yeasts, and lower aerobic stability of corn silage made with an enzyme preparation containing cellulolytic, hemicellulolytic and amylolytic activities (but no inoculant). However, in our study, treatment with L. buchneri and enzymes resulted in silages with the highest concentrations of ethanol. Previously, Oude Elferink et al. (1999) reported that L. buchneri could produce ethanol from anaerobic degradation of lactic acid. Forage treated with IN had more yeasts than untreated forage at the time of ensiling. However, the numbers of total yeasts and molds present in forage at the time of ensiling may not be as important as the number of yeasts that are able to metabolize lactic acid upon exposure of silage to air (Woolford, 1990). In the current study, numbers of yeasts were low (<3.00 cfu/ g) in all of our silages but similar to numbers reported in barley silage by Inglis et al. (1999). Consequently, the aerobic stability of all the silages was extremely prolonged. Regardless of this finding, treatment with the intermediate and high level of L. buchneri improved the aerobic stability of barley silage. Remarkably, silage treated with LB10 did not spoil throughout the 760-h period of monitoring. In other studies, corn silage treated with cfu/g of L. buchneri did not spoil throughout 792- (Driehuis et al., 1999) and 900-h (Ranjit and Kung, 2000) periods of aerobic exposure. The ability to find differences among treatments in aerobic stability, even as found in the current study, are useful because silage may be exposed to air for prolonged periods in the silo before being fed. The IN also contained fibrolytic and saccharolytic enzymes, and silage treated with this inoculant had lower ADF and NDF concentrations compared with untreated silage. However, silage treated with IN contained more (P < 0.05) starch, suggesting that the saccharolytic component of the additive was ineffective. In contrast, the ADF and starch contents of silages treated with the two higher applications of L. buchneri and enzymes were not different from untreated silage. These findings are unexplainable especially because the amounts of enzymes in the silages treated with L. buchneri were three times that of IN. Buffered and unbuffered propionic acid-based products have been successfully used as silage additives to improve the aerobic stability of silages (Britt et al., 1975; Kung et al., 1998). Although high levels of propionic acid (0.5 to 1.0% of fresh forage weight) have been used in previous studies, comparatively much lower levels of application (<0.1 to 0.2% of forage wet weight) have been used more recently with success in corn silage (Kung et al., 1998). In the current study, BP contained 56% active ingredients and was applied at a rate of 0.2% of fresh forage weight. This resulted in a stimulation of silage fermentation to produce more lactic acid. Although silage treated with BP was stable for 240 h more than untreated silage before it began to spoil, a statistically significant improvement in the aerobic stability of the treated silage was not found; this was in clear contrast to previous results with corn silage (Kung et al., 1998). CONCLUSIONS Treatment with an inoculant containing a blend of homolactic acid bacteria, propionibacteria, and enzymes improved silage fermentation by causing more extensive homolactic fermentation and resulted in silage with lower ADF and NDF content. However, the amylolytic enzymes and propionibacteria in the additive appeared to be ineffective. Treatment with a buffered propionic acid-based preservative stimulated fermentation, resulting in higher concentrations of lactic acid and numerically improved aerobic stability. Inoculation with L. buchneri and enzymes resulted in a marked shift towards a production of acetic and propionic acids, with a numerical decrease in the numbers of yeasts. Production of these acids has been suggested to be through the anaerobic conversion of lactic acid rather than a traditional heterolactic fermentation of glucose. Silages treated with L. buchneri to achieve at least cfu/g remained unspoiled when exposed to air for longer periods of time than untreated silage. Treating silages with L. buchneri is an effective method of improving the aerobic stability of barley silages and may be an alternative to other antifungal additives. ACKNOWLEDGMENTS The authors wish to thank Julie Robinson, Jason Mills, Julie Tavares, and Caroline Golt for assistance throughout the study. We thank John Pesek for statistical consultation. REFERENCES Britt, D. G., J. T. Huber, and A. L. Rogers Fungal growth and acid production during fermentation and refermentation of organic acid treated corn silages. J. Dairy Sci. 58: Driehuis, F., S.J.W.H. Oude Elferink, and S. F. Spoelstra Anaerobic lactic acid degradation during ensilage of whole crop maize inoculated with Lactobacillus buchneri inhibits yeast growth and improves aerobic stability. J. Appl. Microbiol. 87: Inglis, G. D., L. J. Yanke, L. M. Kawchuk, and T. A. McAllister The influence of bacterial inoculants on the microbial ecology of aerobic spoilage of barley silage. Can. J. Microbiol. 45: Kung, Jr., L., A. C. Sheperd, A. M. Smagala, K. M. Endres, C. A. Bessett, N. K. Ranjit, and J. L. Glancey The effect of preservatives based on propionic acid on the fermentation and aerobic stability of corn silage and a total mixed ration. J. Dairy Sci. 81: Journal of Dairy Science Vol. 84, No. 5, 2001

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