Rafael Camargo do Amaral

Perdas de silagens de cana-de-açúcar tratadas com aditivos químicos e bacterianos

The experiment was carried out to evaluate sugar cane silage treated with chemical additive: urea 1.5%, sodium benzoate 0.1%, and sodium hydroxide 1.0% on the wet basis, associated with Propionibacterium acidipropionici + Lactobacillus plantarum and Lactobacillus buchneri, plus control silage in a factorial scheme 4 x 3, with three replications. The gas and effluents losses during the fermentation phase, and dry matter recovery were determined. During the aerobic phase were determined the dry matter recovery and aerobic stability through the temperature variation. The Lactobacillus buchneri and NaOH association reduced gas and effluent losses and increased the dry matter recovery. At the aerobic phase, the sodium benzoate maintained the pH values, with changes of 0.1 unit during five days. The time to temperature elevation increased from 34 hours on the control silage to 54.0 and 50.0 hours, respectively on the silage inoculated with Propionibacterium acidipropionici + Lactobacillus plantarum or Lactobacillus buchneri. The sugar cane silage production required an efficient additive inclusion which can control the quantitative losses during the fermentation and aerobic phases.

Performance of dairy cows fed high levels of acetic acid or ethanol

Ethanol and acetic acid are common end products from silages. The main objective of this study was to determine whether high concentrations of ethanol or acetic acid in total mixed ration would affect performance in dairy cows. Thirty mid-lactation Holstein cows were grouped in 10 blocks and fed one of the following diets for 7 wk: (1) control (33% Bermuda hay + 67% concentrates), (2) ethanol [control diet + 5% ethanol, dry matter (DM) basis], or (3) acetic acid (control diet + 5% acetic acid, DM basis). Ethanol and acetic acid were diluted in water (1:2) and sprayed onto total mixed rations twice daily before feeding. An equal amount of water was mixed with the control ration. To adapt animals to these treatments, cows were fed only half of the treatment dose during the first week of study. Cows fed ethanol yielded more milk (37.9 kg/d) than those fed the control (35.8 kg/d) or acetic acid (35.3 kg/d) diets, mainly due to the higher DM intake (DMI; 23.7, 22.2, and 21.6 kg/d, respectively). The significant diet × week interaction for DMI, mainly during wk 2 and 3 (when acetic acid reached the full dose), was related to the decrease in DMI observed for the acetic acid treatment. There was a diet × week interaction in excretion of milk energy per DMI during wk 2 and 3, due to cows fed acetic acid sustained milk yield despite lower DMI. Energy efficiency was similar across diets. Blood metabolites (glucose, insulin, nonesterified fatty acids, ethanol, and γ-glutamyl transferase activity) and sensory characteristics of milk were not affected by these treatments. Animal performance suggested similar energy value for the diet containing ethanol compared with other diets. Rumen conversion of ethanol to acetate and a concomitant increase in methane production might be a plausible explanation for the deviation of the predicted energy value based on the heat of combustion. Therefore, the loss of volatile compounds during the drying process in the laboratory should be considered when calculating energy content of fermented feedstuffs.

Características fermentativas e químicas de silagens de capim-marandu produzidas com quatro pressões de compactação

The objective of this experiment was to evaluate the fermentative and chemical parameters of four different bulk densities of marandugrass (Brachiaria brizantha) silages. The forage was harvested with 60 days of vegetative growth and 32% of DM. The bulk densities used were 100, 120, 140 and 160 kg DM/m3. Treatments were distributed in a completely randomized design with four replicates. Gas production data were analyzed by repeated measures model. The lower density silages showed greater gas production. Low effluent production was observed in all treatments due to the high forage DM during harvesting. Higher bulk density silos showed lower DM losses and also achieved a lower pH than lower density silos. Ammoniacal nitrogen concentration was not influenced by treatments and the observed values were satisfactory for tropical grasses silages. Bulk density increase provided a reduction in NIDN, B3 fraction, NDF and ADF concentration. Higher bulk densities also provided greater DM recovery and greater true in vitro DM digestibility.

Short-term effects of silage volatile compounds on feed intake and digestion in beef cattle.

Two experiments were conducted to evaluate whether fermentation end products in silage affect intake and digestion in beef cattle. Six rumen-cannulated Nellore steers were randomly assigned to a replicated 3 × 3 Latin square design with 14-d periods. Each period consisted of 9 d for adaptation and 5 d for sample collection. Steers were housed in a tie-stall barn and individually fed once daily at 0800 h. The dietary treatments in Exp. 1 were as follows: 60% corn silage plus 40% concentrate (CON), 60% corn silage with added ethanol (2.8% on a DM basis) and 40% concentrate (ET), and 60% corn silage with added lactic acid (5.4% on a DM basis) and 40% concentrate (LA). The DMI was similar (P = 0.41) across treatments (average 11.7 kg/d); however, the LA treatment increased the ruminal pH (P = 0.01) and decreased the acetate:propionate ratio (P < 0.01). Diet digestibility decreased by 2.2 to 2.5 percentage units when the DM content was determined by oven drying (at 105°C) rather than by toluene distillation. The treatments in Exp. 2 were as follows: 75% sugarcane silage with no volatile fraction (oven dried at 60°C and rehydrated) and 25% concentrate (75D), 75% sugarcane silage (original moisture content) and 25% concentrate (75W), and 40% sugarcane silage and 60% concentrate (40W). Approximately 21% of the DM content of sugarcane silage consisted of volatile compounds. The presence of these compounds did not alter the DMI (P = 0.36) but did increase both the acetate:propionate ratio (P < 0.01) and the fractional absorption rates of valerate (P < 0.01) and ethanol (P = 0.02) in the empty reticulorumen. The 40W diet led to a greater DMI (40W = 9.79 vs. 75W = 6.19 kg/d; P < 0.01), which altered most of the measured variables traditionally associated with high-concentrate diets. As in Exp. 1, diet digestibility decreased by 1.5 to 5.4 units when the DM content was determined by oven drying at 105°C rather than by toluene distillation. In this short-term study, volatile compounds did not inhibit the DMI or the digestion process of the animals. On the contrary, volatile compounds contributed to the energy content of the silage, composing up to 10% of the energy value as determined by digestibility. Due to the short experimental periods, the results from this study should be interpreted with caution.

Cana-de-açúcar in natura ou ensilada com e sem aditivos químicos: estabilidade aeróbia dos volumosos e das rações

The objective of this experiment was to evaluate the susceptibility to aerobic deterioration and dry matter losses of fresh sugarcane and silages with or without chemical additives, and diets composed formulated with these bulks. The experiments were conducted in a complete randomized design with four replications, consisting of fresh or ensilaged sugarcane with calcium oxide or limestone at the level of 1% fresh matter. The aerobic stability was assessed of the bulks and diets by monitoring temperature, pH and dry matter losses during ten days. The treatment sugarcane with calcium oxide improved aerobic stability, shown by the longer time needed to raise the temperature and the smaller dry matter losses. Fresh sugarcane was more susceptible to deterioration, showing the highest temperature increase and dry matter losses. Diets containing bulk also showed the superiority of the silage treated with chemical additives and improvement in aerobic stability, compared to bulks without the diet components. The additives were shown to be effective in improving silage stability and reducing dry matter losses. Fresh sugarcane was more susceptible to aerobic deterioration than silages. Diets containing sugarcane silage with additives delayed the aerobic deterioration and may be a possible strategy to improve farm nutritional management.

Estabilidade aeróbia de silagens do capim-marandu submetidas a diferentes intensidades de compactação na ensilagem

This trial aimed to evaluate the aerobic stability of marandu grass silages submitted to different packing intensities. The forage was harvested at 60 days of regrowth. The following packing densities were evaluated: 100, 120, 140, and 160 kg DM/m3. Silage chemical changes were determined 0, 3, and 6 days after air exposure and temperature recorded every 12 hours, during 156 hours after the buckets were placed in the climatic camera. Thermometers were inserted 10 cm into the silage mass. Data were analyzed following a repeated measures model in a complete randomized design with four replications. The silage with the highest density reached the maximum temperature value in a longer period, compared to the lowest density one, probably due to the highest stability. The pH values increased and ammoniacal nitrogen (N-NH3/TN) decreased during the air exposure phase. The NDIN (neutral detergent insoluble nitrogen) and B3 fractions decreased for the highest density silage, characterizing the participation of these fractions in the proteolysis process during the aerobic phase. The NDF (neutral detergent fiber) and ADF (acid detergent fiber) values increased during the aerobic exposure and the highest values were observed on the lowest density silages. The highest density silages showed higher true in vitro digestibility values compared to the other silages.

Chemical and microbiological changes and aerobic stability of marandu grass silages after silo opening

This trial had the objective of characterizing the microbial population and evaluating the aerobic stability of Marandu grass silages with pelleted citrus pulp (PCP). The collected forage was submitted to the following treatments: Silage of Marandu grass; silage of Marandu grass + 50 g/kg PCP and silage of Marandu grass + 100 g/kg PCP on natural matter basis. Metal cylindrical containers with 80 cm of height and 50 cm of diameter were used as silos during assays of microbiological dynamics and chemical changes of silages in anaerobiosis. Evaluations were performed on days 0, 2, 4 and 6 after silos were opened. The aerobic stability was evaluated by change in temperature, using approximately three kilograms of silage inside styrofoam boxes that were placed inside a climatic chamber. A completely randomized experimental design and split plot arrangement were used in the two assays, with five replications. Treatments were the plots and time was the subplots. Bacillus and enterobacteria were present on the Marandu grass silages with 0 g/kg PCP, which also showed pH increase throughout the feedout phase. Yeast was detected on the silages that were added with PCP. A trend of increasing temperature with extension of the aeration time was observed mainly in the silages containing 100 g/kg PCP. Isolated yeast strains showed lactate assimilation. Silages were found to be unstable due to the silo opening, both by bacterial or yeast development, which reduced the nutritional value.

Glycerol adsorption on a defected Pt6/Pt(100) substrate: a density functional theory investigation within the D3 van der Waals correction

We report an ab initio investigation based on density functional theory calculations within the van der Waals (vdW) correction to obtain an improved atomistic understanding of the adsorption properties of glycerol on a defected Pt6/Pt(100) substrate, which includes low-coordinated Pt sites and well defined Pt(100) terraces. We found that in the lowest energy structure glycerol weakly adsorbs on a low-coordinated cationic Pt site via one of the anionic O atoms with the central carbonate chain orientated nearly parallel to the surface plane. As expected, the vdW correction enhances the adsorption energy, however, while it does not change the adsorption site preference, it affects the orientation of the CCC frame with respect to the substrate. Our results of the work function and Bader charges suggest a negligible charge transfer between glycerol and the Pt6/Pt(100) substrate, which can be attributed mostly to polarizations between the atoms of the molecule and of the surface.

The influence of covering methods on the nutritive value of corn silage for lactating dairy cows

The objective of this study was to evaluate the effect of covering methods on the nutritive value of corn silage and performance of dairy cows. Whole-plant corn was harvested at 340 g/kg of dry matter (DM) and ensiled for 135 d in horizontal silos covered with one of the following methods: oxygen barrier film (45-µm thick) + white-on-black polyethylene film (200-µm thick) over the oxygen barrier film (OB+WB); white-on-black polyethylene film (200-µm thick) (WB); black polyethylene film (200-µm thick) (B); or recycled black polyethylene film (200-µm thick) covered with a layer of 10 cm of sugarcane bagasse (RB+SB). Nutrient composition, fermentation profile, and yeast and mold counts in edible silages were similar across treatments. Silage temperature during the storage period was 24.6, 28.7, 28.4 and 33.1 °C for RB+SB, OB+WB, WB and B, respectively, and the proportion of spoiled silage ranged from 28.7 (for the RB+SB treatment) to 74.2 g/kg DM (for the B treatment). Dry matter intake was similar across treatments and averaged 21.9 kg/d. Milk production was higher for cows fed corn silage covered with RB+SB (34.4 kg/d) compared with those fed corn silage covered with B (30.4 kg/d), resulting in higher feed efficiency for RB+SB treatment. Silages covered with OB+WB and WB had intermediate values. In vivo digestibility of organic matter was higher for cows fed corn silage covered with RB+SB compared with those fed corn silage covered with WB and B, but were similar to those fed corn silage covered with OB+WB. The utilization of oxygen barrier films and the protection of polyethylene film with sugarcane bagasse are effective strategies to increase the recovery of digestible nutrients and, consequently, to enhance production efficiency of lactating dairy cows.

From Bulk CeO 2 to Transition-Metal Clusters Supported on the CeO 2 (111) Surface: A Critical Discussion

Nowadays, cerium oxide compounds, such as CeO 2 , Ce 2 O 3 , etc, play a crucial role in catalysis as support for transition-metal particles, which can be attributed to their high thermodynamic stability and oxygen storage capacity. A wide range of experimental techniques and theoretical approaches have been used to identify the key aspects that determine the success or failure of cerium oxide compounds within catalysis. However, theoretical studies based on ab-initio calculations for cerium oxides started to became common only in the past decade, in particular, due to the challenge to describe the delocalized and localized nature of the Ce 4 f -states in Ce IV and Ce III , respectively. These electronic properties affect the oxidation state and ionic size of the Ce atoms within oxides as well as interaction with transition-metal clusters. Here, due to the brief nature of this review, we revise mainly our results based on density functional theory within the Hubbard U model for the bulk CeO 2 and Ce 2 O 3 , the unreduced and reduced CeO 2 (111) surface, and transition-metal clusters supported on CeO 2 (111).