Caracterização de silagens de milho produzidas em Minas Gerais e caracterização metabólica e genotípica de bactérias do ácido lático isoladas dessas silagens

Abstract

The present study was conducted with the objective to understand the silage practices, as well as their correlation with bromatological, microbiological and fermentation characteristics of corn silage produced in dairy farms located in Campo das Vertentes, South and Southwest of Minas Gerais State mesoregions. Also, the objective was to identify and characterize metabolic and genotypically the lactic acid bacteria (LAB) isolated in these silages. In the first experiment, we made a survey about the corn silage production and use practices, milk production characteristics, bromatological and microbiological analysis and metabolite profile of silages produced in the regions. Despite the predominance of small producers, proportionally, with smaller participation on the total volume of milk produced, large specialized properties were observed in the region and the silage quality was associated with the degree of specialization of the farm. Great diversity between the ensiling practices was observed and this reflected both the nutritional quality, and the fermentative and microbiological profile of the evaluated silages and consequently in animal productivity. The chemical composition and the microorganisms population in evaluated silages showed average values within the recommended for good quality corn silage. In the second experiment, there was a group of BAL isolated from silages evaluated based on metabolite production profile and the genetic profile through the techniques of RAPD-PCR and REP-PCR. The profiles obtained by the RAPD-PCR using the primer M13 were more discriminatory than those obtained with REP-PCR using the primer (GACA) 4. All strains were grouped according to their respective designations taxonomical by RAPD-PCR and were identified as Lactobacillus acidophilus, L. buchneri, L. casei, L. diolivorans, L. hilgardii, L. paracasei, L. parafarraginis, L. plantarum, L. rhamnosus, L. zeae, and Pediococcus acidilactici. Lactobacillus rhamnosus and L. buchneri showed great amplitude distribution across regions. Metabolic characteristics of strains allowed the grouping in accordance with the production of metabolites profile evaluated and correlated with results obtained for genotypic characterisation.