The objectives of this study were to characterize and quantify the microbial populations in guinea grass (Panicum maximum Jacq. cultivar Mombasa) harvested at different regrowth intervals (35, 45, 55, and 65 d). The chemical composition and fermentation profile of silages (after 60 d) with or without the addition of a microbial inoculant were also analyzed. Before ensiling, samples of the plants were used for the isolation and identification of lactic acid bacteria (LAB) in the epiphytic microbiota. A 4 × 2 factorial arrangement of treatments (4 regrowth intervals × with/without inoculant) was used in a completely randomized design with 3 replications. Based on the morphological and biochemical characteristics and the carbohydrate fermentation profile, Lactobacillus plantarum was found to be the predominant specie of LAB in guinea grass forage. Linear increases were detected in the dry matter (DM) content and concentrations of neutral detergent fiber, acid detergent fiber, acid detergent insoluble nitrogen, and DM recovery as well as linear reductions in the concentrations of crude protein and NH3-N with regrowth interval. Additionally, linear reductions for gas and effluent losses in silages were detected with increasing regrowth interval. These results demonstrate that guinea grass plants harvested after 55 d of regrowth contain a LAB population sufficiently large to ensure good fermentation and increase the DM recovery. The use of microbial inoculant further enhanced the fermentation of guinea grass at all stages of regrowth by improving the DM recovery.
-Microbial populations, pH, ammonium nitrogen/total nitrogen (N-NH 3 ) ratio, concentrations of lactic acid, acetic acid and butyric acid and the chemical composition of Brachiaria decumbens cv. Basiliski silages at different regrowth ages (30, 40, 50, 60 and 70 days) were evaluated by using 2-kg capacity laboratory silos. It was used a 5 × 6 factorial scheme (5 regrowth ages × 6 fermentation periods) in a complete random design, with three replicates. The fermentation periods were 1, 3, 7, 14, 28 and 56 days. Lactic acid bacteria populations were recorded in fresh forage varying from 3.93 (30 days of regrowth) to 5.51 (70 days of regrowth) log colony-forming units (cfu)/g forage. Maximum populations of these microorganisms were recorded in the silages on the seventh day of fermentation (8.69 log cfu/g silage). Enterobacteria populations persisted until the 28 th day, with maximum values found as early as the first day of fermentation (7.89 log cfu/g silage). Levels of DM, NDF, ADF and ADIN increased linearly whereas values of CP decreased linearly with age of regrowth of the plants. There was a linear reduction in the levels of DM, CP and NDF and linear increase in the levels of ADIN over the period of fermentation. N-NH 3 level decreased and increased linearly with regrowth age and fermentation period, respectively. The pH decreased exponentially with fermentation period. Lactic acid increased and butyric acid decreased linearly with regrowth age. The predominant Lactobacillus plantarum species in signalgrass plants is Lactobacillus plantarum.Key Words: acetic acid, butyric acid, enterobacteria, lactic acid, lactic acid bacteria Populações microbianas, perfil fermentativo e composição bromatológica de silagens de capim-braquiária em diferentes idades de rebrotação RESUMO -Foram avaliadas as populações microbianas, o pH, a relação nitrogênio amoniacal/nitrogênio total (N-NH 3 ), as concentrações de ácidos láctico, acético e butírico e a composição bromatológica de silagens de Brachiaria decumbens cv. Basiliski de cinco idades de rebrotação (30, 40, 50, 60 e 70 dias) utilizando-se silos laboratoriais de 2 kg de capacidade. Utilizou-se um esquema fatorial 5 × 6 (5 idades de rebrotação × 6 períodos de fermentação), em um delineamento inteiramente casualizado, com três repetições. Os períodos de fermentação foram 1, 3, 7, 14, 28 e 56 dias. Na forragem fresca, foram registradas populações de bactérias do ácido láctico variando entre 3,93 (30 dias de rebrotação) e 5,51 (70 dias de rebrotação) log unidades formadoras de colônia (ufc)/g de forragem. Nas silagens, foram registradas populações máximas desses microrganismos no sétimo dia de fermentação (8,69 log ufc/g de silagem). As populações de enterobactérias persistiram até o 28 o dia, com os valores máximos observados logo no primeiro dia de fermentação (7,89 log ufc/g de silagem).
a b s t r a c tThe effects of dietary substitution of soybean meal (SBM) with ethanol-treated jatropha kernel cake with seed shells (TJC) on nutrient intake and digestibility, nitrogen balance, pH, rumen ammonia nitrogen (NH 3 -N), serum levels of alanine aminotransferase (ALT, EC 2.6.1.2) and aspartate aminotransferase (AST, EC 2.6.1.1), and ruminal degradation kinetics of SBM and TJC crude protein (CP) in Holstein heifers were evaluated. Four rumen-cannulated heifers were distributed in a 4 Â 4 Latin square design, [body weight (BW) ¼ 379 72.13 kg]. Each experimental period lasted 15 days, with eight days for diet adaptation and seven days for data collection. The heifers were fed four complete isonitrogenous diets containing 65% corn silage and 35% concentrate on a dry matter (DM) basis. The treatments consisted of four levels of SBM substitution for TJC þurea/ammonium sulfate: 0, 33, 67, and 100%, on a DM basis. Ethanol treatment of the jatropha kernel cake removed 4 99% of the phorbol esters. The effective degradability of the CP for TJC was 425.6 g/kg. Intakes of DM, organic matter (OM), CP, ether extract (EE), neutral detergent fiber (NDF) and total digestible nutrients (TDN) decreased linearly with the substitution of SBM with TJC. The DM intakes were 18.0, 16.2, 16.8 and 11.3 g/kg BW for 0, 33, 67 and 100% substitution, respectively. There was no effect of the TJC inclusion level on nutrient digestibility. The rumen pH increased linearly with increasing substitution levels. The rumen NH 3 -N was not affected by the inclusion of jatropha (7.79 mg/dL overall mean). The amounts of ingested and absorbed nitrogen (N) and the N-balance decreased linearly with increasing TJC levels. The serum levels of ALT and AST were not affected by the inclusion of TJC in the diets. Despite the decrease in phorbol esters, ethanol treatment of jatropha kernel cake was not enough to promote adequate nutrient intake by the heifers.
This study aimed to assess the wild fire propagation risk to wildfires in the Itacolomi State Park, in Minas Gerais State, Brazil, using GIS and to compare the efficiency of the incident solar radiation over the aspect variable. The following variables were used: land cover/use (LCU), slope (SLP), slope curvature (CUR), aspect (ASP) and incident solar radiation (SOL). The weights of each variable were calculated from the ratio between the total area and the burned area of each class in order to generate the fire propagation risk maps. Fire data from 2016 to 2019 were used for validation. When the moderate risk class was considered susceptible, inadequate precision was observed for both methods (ASP and SOL). On the other hand, when the moderate class was considered non-susceptible to fire, the results presented moderate accuracy. Furthermore, the methods using SOL and ASP showed similar results. The results can guide fire mitigation actions on the park.
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