Estabilidade aeróbia de silagens de capim-mombaça tratadas com Lactobacillus buchneri

Abstract

RESUMO -Objetivou-se avaliar o efeito da adição de duas cepas de Lactobacillus buchneri sobre a estabilidade aeróbia de silagens de capim-mombaça. O experimento foi conduzido em delineamento inteiramente casualizado com três repetições, em esquema de parcelas subdivididas no tempo, de modo que os tratamentos (silagens sem inoculantes e com inoculante experimental e comercial) foram aleatorizados nas parcelas e os tempos de avaliação aeróbia das silagens (0, 2, 8 ou 10 dias após a abertura dos silos) nas subparcelas. Após 90 dias de armazenamento, os silos foram abertos e amostras de aproximadamente 2,5 kg foram retiradas para avaliação da estabilidade aeróbia com base na temperatura de cada amostra.As mudanças químicas e microbiológicas foram avaliadas. Após abertura dos silos, verificou-se aumento nas populações de bactérias do ácido lático, leveduras e fungos filamentosos. Houve aumento nos valores de pH resultante da redução da concentração dos ácidos orgnicos e de aumentos dos teores de matéria seca e proteína bruta. A adição de L. buchneri às silagens melhorou sua estabilidade, enquanto a silagem sem inoculante apresentou estabilidade de 55 horas. As silagens inoculadas não ultrapassaram essa temperatura limite em um período de 10 dias. A melhoria da estabilidade foi ocasionada pela associação de altas concentrações de cido acético ao ácido propiônico e pela menor concentração de ácido lático no momento de abertura, o que inibiu a proliferação de fungos filamentosos e leveduras após abertura dos silos.Palavras-chave: ácido acético, ácido lático, fermentação, microbiologia, temperatura Aerobic stability of mombaça grass silages treated with Lactobacillus buchneriABSTRACT -This study aimed to evaluate the effect of the addition of two L. buchneri strains on the aerobic stability of the Mombaça grass silages. The experiment was carried out in a completely randomized design with three replicates in split-plot in time scheme, so that the treatments (silages without inoculant and with experimental or commercial inoculants) were randomized on plot and in times of aerobic evaluation of the silages (0, 2, 8, and 10 days after the opening of the silos) as subplots. After an storage period of 90 days, the silos were opened and samples of about 2,5 kg were collected for the evaluation of the aerobic stability based on the temperature for each sample. The chemical and microbiological changes in the silages were evaluated. As soon as the silos were opened, changes in the silages were observed, with increases in the lactic acid bacteria, yeast and filamentous fungus populations. Also, the pH values increased due to the reduction in the organic acids concentration and to the increase in the DM and CP contents. The addition of L.buchneri to the silages increased their stability. The silages without inoculant was stable

Microbial and fermentation profiles, losses and chemical composition of silages of buffel grass harvested at different cutting heights

“…Based on the literature for tropical grasses, the DM content ranges from 157.8 to 280 g/kg (Patrizi et al, 2004;Ribeiro et al, 2008;Ávila et al, 2009;Silva et al, 2011). According to McDonald et al (1991), the optimum dry matter content for good quality silages ranges from 300 to 350 g/kg.…”

“…Regarding the increase in the CHO contents with greater cutting heights, these values are considered to be low and characteristic of tropical grasses (Ribeiro et al, 2008;Ávila et al, 2009;Vasconcelos et al, 2009). However, the mean level of silage CHO was 7.2 g/kg, regardless of cutting height.…”

Effect of sward height on the fermentability coefficient and chemical composition of Guinea grass silage

“…Owing to these restrictions, several studies have tried to identify alternatives to improve the fermentative profile of tropical-grass silages and to reduce DM loss. The primary objective of these studies was to identify the number of days of regrowth for harvesting and the effect of the additives ( Avila et al, 2009;Bernardes et al, 2008;Vasconcelos et al, 2009), and they indicated that the appropriate age at harvesting for most tropical forage grasses should be between 50 and 65 days of regrowth ( Avila et al, 2009;Santos, Zanine, Dantas, et al, 2008;Vasconcelos et al, 2009).…”

“…The results from available studies on tropical-grass silage quality are difficult to compare as the harvesting of each grass was made with different ensilability parameters; e.g., when we analysed the data for Guinea grass harvested for silage from 55 to 65 days of regrowth ( Avila et al, 2009 When the pre-established sward height was reached, the grass was recorded inside two quadrats, each of 1 9 1 m (n = 4). All herbage green weights were recorded, and a composite sample per experimental unit was harvested and used for morphological separation into leaf (height of the ligule), stem (stem + sheath), senescent mass (tissue with more than 50% senescence) and inflorescence.…”

“…The conventional method of harvesting tropical grasses for silage based on days of regrowth( Avila et al, 2009;Santos, Zanine, Dantas, et al, 2008;Vasconcelos et al, 2009) might be unreliable when seeking a pattern in FC. Hence, sward height might be a viable alternative because it presents a tendency to standardize sward structure and consequently FC at the time of harvesting Guinea grass.…”