A meta-analytical study about the impact of homofermenters bacteria on the chemical composition and fermentation of corn silage in Brazil

Our objective was to evaluate the impact of homofermenters bacteria on the chemical composition and fermentation of corn silage produced in Brazil, using a meta-analysis. The database (only peer-reviewed articles were selected) was composed of 138 observations (treatments means) from 19 studies concerning corn silage treated with inoculants. Inoculants were comprised of several lactic-acid bacteria (i.e., Lactobacillus acidophilus, L. curvatus, L. plantarum, Pediococcus acidilactici, P. pentosaceus, and Streptococcus faecium). The treatments were classified into two categories: 1) silages without inoculant (untreated), and 2) silages treated with silage inoculants (inoculated). A minimum of two studies per treatment was the prerequisite for keeping the dependent variables in the final database. Data were analyzed using the MIXED procedure of SAS (v. 9.4). Differences between means were determined using the PDIFF, which differentiates means based on Fisher?s F- protected least significant difference test. Because the variation across experimental protocols the study effect was included in the model through the RANDOM statement. Significance was declared at P <= 0.05. The chemical composition of corn silage was unaffected by application of homofermenters bacteria (P > 0.05), and the overall means observed for dry matter (DM), crude protein, neutral detergent fiber, and in vitro dry matter digestibility were 319.3 g/kg as fed, 73.3, 542.4, and 575.8 g/kg of DM, respectively. Despite of fermentation patterns, lactic (overall mean = 51.3 g/kg of DM), acetic (overall mean = 14.5 g/kg of DM), and butyric acids (overall mean = 0.29 g/kg of DM) were unaffected (P > 0.05) by inoculation. Silage pH (overall mean = 3.83) was unaffected (P > 0.05) by inoculation. Concentrations of ethanol (overall mean = 11.7 g/kg of DM) and ammonia-N (overall mean = 75.2 g/kg of total N) were also similar (P > 0.05) between untreated and inoculated silages. Moreover, inoculation did not alter (P > 0.05) DM losses (overall mean = 54.2 g/kg of DM). The improvements on corn silage claimed by utilization of homofermenters bacteria did not occur.