Composição bromatológica, perfil fermentativo e populações microbianas em silagens de gramíneas tropicais

• Autor(a) principal: Rigueira, João Paulo Sampaio
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1787
• topic: Amônia; Bactéria do ácido lático; Carboidratos solúveis; PH; Ammonia; Lactic acid bacteria; Soluble carbohydrates; PH; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::PASTAGEM E FORRAGICULTURA::AVALIACAO, PRODUCAO E CONSERVACAO DE FORRAGENS

This study consisted of three experiments. At first evaluated the microbial populations, fermentation profile and the chemical composition of Brachiaria brizantha cv. Basilisk and mombaça grass silage under different levels of nitrogen (N). The N rates used were 0, 30, 60 and 90 kg ha-1. Lactobacillus fermentum was the predominant lactic acid bacteria species in tropical grass. Interaction effect of N rate x grass species (P<0.05) was observed on dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and soluble carbohydrates (CHO) of silages. The values of pH and gas losses were influenced (P<0.05) only by forage species, with higher values for mombaça grass. For contents of ammonia (NH3-N) and effluent losses observed interaction effect (P<0.05) between forage species x N rates, refistering the highest NH3-N and effluente losses in mombaça grass silage fertilized with 60 kg N ha-1. There was also that N fertilization decreased DM in forages and increases the CP, NH3-N and effluent losses in silage. It is concluded that nitrogen does not favor the fermentation profile and increases the DM losses in grass silage. In the second experiment, evaluated the fermentation profile, chemical composition, the microbial population and the recorvery of dry matter in marandu grass silages consortium with different levels of estilosantes cv. Campo Grande treated or not with inoculant. It was used a factorial 4 x 2 (four level of estilosantes x with and without inoculants) in a completerly randomized design with four replications. The levels of estilosantes in ensiled mass were 0, 10, 20 and 30% of the total weight in natural matter. The purpose of using these levels was to simutate a pasture grass and legume intercropping in different proportions of estilosantes. There was interaction effect (P<0.05) between the levels of estilosantes and inoculants for DM, effluente losses, dry matter recorvery and population of fungi and yeasts. The effect of inoculants (P<0.05) was observed only for the population of lactic acid bacteria (LAB) on silage. For the loss of gas, there was no significant differences (P<0.05) in any of the treatments. There was an increase (P<0.05) in DM, ash, and CP with increased levels of estilosantes. With respect to fiber content, it was lower (P<0.05) NDF and ADF concentrations with increased levels of estilosantes in silage. The addition growing of estilosantes improved silage fermentation by decreasing (P<0.05) pH values and ammonia nitrogen (NH3-N). Was observed higher (P<0.05) population of LAB inoculated silages and with higher estilosantes level. Was observed higher (P<0.05) dry matter recorvery for treatments with 10 and 20% of estilosantes, irrespective of the use of microbial inoculants. Conclude that the mixture of marandu grass with estilosantes improves the chemical composition and fermentation profile, in addition reducing the losses of dry matter silages regardless of the use of microbial inoculants. In the third experiment, evaluated the microbial population, the fermentation profile and chemical composition of marandu grass silage treated with commercial microbial inoculants or inoculants isolated from tropical grasses. Was used factorial 3 x 6 (three inoculants x six fermentation periods) in a completely randomized design with three replications. The fermentation periods were 1, 3, 7, 14, 28 and 56 days after the close of the silos. There was less (P<0.05) content of neutral detergent fiber for the treatment with inoculant M17. There was no effect of inoculant (P>0.05) in CP and ADF concentration. For the DM content, there was an increase (P<0.05) in silages inoculated with Sil All C4. There was interaction effect between inoculants and fermentation periods for the LAB population and pH. The silages inoculated with Sil All C4 had lower (P<0.05) pH on the first day, but at 56 days the observed value was higher (P<0.05) to the other treatments. The concentration of ammonia nitrogen was higher (P<0.05) in silagens inoculated with M17 as compared to control. Linear increase was observed with the progress of the fermentation period for all treatments. Regarding the microbial population, there was greater (P<0.05) population of fungi and yeasts in silage and lower control population (P<0.05) in LAB silages inoculated with M17 to three days of fermentation. Conclude that the use of microbial silage additives in marandu grass silage not show of benefit for the fermentation profile and chemical composition.