Determinação de ácido ascórbico e carotenóides totais em amostras de polpa de pitaia branca (hylocereus undatus) e vermelha (hylocereus polyrhizus) submetidas a procedimentos térmicos / Determination of ascorbic acid and total carotenoids in white (hylocereus undatus) and red (hylocereus polyrhizus) pulp samples submitted to thermal procedures

A pitaia é uma cactácea frutífera originária das Américas e vem se estabelecendo economicamente em diversos países, como o Brasil. É uma fruta que possui baixo teor calórico e quantidade expressiva de vitaminas, minerais e compostos antioxidantes. Neste contexto, o estudo tem com intuito determinar a concentração de ácido ascórbico (vitamina C) e carotenóides totais em amostras de polpa de pitaia branca e vermelha comercializadas na cidade de Janaúba – Minas Gerais. Empregou-se a titulometria para a determinação de ácido ascórbico e a espectrofotometria UV/visível para a determinação carotenóides totais nas polpas de duas espécies de pitaias (Hylocereus undatus e Hylocereus polyrhizus) que foram submetidas à procedimentos de aquecimento e congelamento. Os teores de ácido ascórbico nas amostras de pitaias branca e vermelha in natura são condizentes com a literatura. Para a maior parte das amostras houve uma correlação positiva entre a temperatura e o tempo de exposição, exceto para a pitaia de polpa vermelha. Os teores de carotenóides totais para as amostras de pitaia de polpa vermelha decresceram com o tempo de armazenamento em ambos os processos (congelamento e aquecimento). Para a pitaia de polpa branca não foi possível determinar a concentração de carotenóides totais empregando a espectrofotometria UV/visível. Baseando-se neste estudo, conclui-se que a pitaia branca e vermelha apresentaram quantidades significativas de ácido ascórbico, podendo ser agregado à alimentação devido ao seu efeito protetor para organismo, sendo seu extrato um potencial substituinte dos ingredientes artificiais utilizados na indústria. 

Efeito da adubação nitrogenada e correlações entre parâmetros morfogênicos e estruturais em pastos de capim-braquiária

The objective of this work was evaluate the association between morphogenetic and structural characteristics of Brachiaria decumbens managed at different doses of nitrogen. The experimental design was a randomized block with four replications. Four levels of nitrogen fertilization were evaluated: 100; 200; 300 and 400 kg of N ha-1 as urea, divided in two doses during the rainy season (January to March) and the control treatment without fertilization. There was an increase in leaf appearance rate (LAR), leaf elongation rate (LER) and tiller number (NP) up to 21.4%; 23.8% and 50.5% for the highest dose of N (400 kg N ha-1) compared to the control group, respectively. There was a positive correlation (r = 0.53) (p<0.05) between the LER and leaf life span (LLS). The phyllochron showed high negative correlation (r = -0.81) (p<0.0001) with LAR. Regarding the final length of the stem, there was no correlation effect (p>0.05) with other analyzed characteristics.Objetivou-se por meio deste trabalho avaliar a associação entre características morfogênicas e estruturais da Brachiaria decumbens manejada em diferentes doses de nitrogênio. O delineamento experimental utilizado foi o de blocos ao acaso com quatro repetições. Foram avaliados quatro doses de adubação nitrogenada: 100, 200, 300 e 400 kg ha-1 de N na forma de ureia, divididas em duas aplicações durante o período chuvoso (janeiro e março) e o tratamento controle, sem adubação. Observou-se incremento na taxa de aparecimento foliar (TApF), taxa de alongamento foliar (TAlF) e número de perfilhos (NP) de até 21,4%; 23,8% e 50,5% para a mais elevada dose de N (400 kg de N ha-1) em relação ao grupo controle, respectivamente. Houve correlação positiva (r = 0,53) (p<0,05) entre a TalF e duração de vida da folha (DVF). O filocrono apresentou alta correlação negativa (r = -0,81) (p<0,0001) com a TApF. Em relação ao comprimento final do colmo, não houve efeito de correlação (p>0,05) com as demais características analisadas

Chemical composition, fermentation profile and microbial populations in tropical grass silages

Este estudo envolveu três experimentos. No primeiro, avaliaram-se as populações microbianas, o perfil fermentativo e a composição bromatológica de silagens de capim-braquiária cv. Basilisk e capim-mombaça sob diferentes doses de nitrogênio (N). As doses de N utilizadas foram 0, 30, 60 e 90 kg ha-1. A espécie de bactéria do ácido lático predominante nos capins foi o Lactobacillus fermentum. Observou-se efeito de interação dose de N x espécie forrageira (P0,05). Verificou-se aumento (P0,05) nos teores de PB e FDA. Para o teor de MS, foi observado um aumento (P0.05) 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.Fundação de Amparo a Pesquisa do Estado de Minas Gerai

Soybean silage (Glycine max (L.) Merril) in beef cattle feeding

Foram conduzidos dois experimentos objetivando-se avaliar o consumo, a digestibilidade total e parcial dos nutrientes, o pH e a concentração de amônia ruminal (experimento1), bem como o desempenho produtivo de bovinos de corte (experimento 2) que receberam dietas contendo silagem de soja (SS), silagem de soja com inoculante microbiano (SSI), silagem de soja com inoculante e melaço (SSIM) e silagem de soja com melaço (SSM). O inoculante utilizado foi o Sil All C4 (Alttech, Brasil). O melaço em pó foi utilizado na proporção de 2,5% na matéria natural. As dietas, isonitrogenadas, apresentaram 13% de proteína bruta. A relação volumoso:concentrado foi de 70:30, com base na matéria seca, sendo 40% de silagem de soja e 30% de silagem de milho. No primeiro experimento, foram utilizados quatro animais mestiços HxZ, fistulados no rúmen e no abomaso, com peso inicial médio de 230 kg, distribuídos em um quadrado latino 4x4. Usou-se o óxido crômico para estimativa do fluxo de digesta abomasal e excreção fecal. Os consumos de nutrientes, expressos em kg/dia, assim como suas respectivas digestibilidades aparentes totais, ruminais e intestinais não foram influenciados (P>0,05) pelas dietas. No entanto, o consumo de MS, em porcentagem do peso vivo e g/kg0,75 foi influenciado (P0,05) de dieta, tempo de coleta, nem da interação destes fatores para os valores de amônia e pH, cujos valores médios foram 11,91mg/100 mL e 6,45, respectivamente. A taxa de passagem, também não foi influenciada pelas dietas, estimando-se valor médio de 5,48% hora-1. No experimento 2, foram utilizados 32 animais HxZ, não castrados, com peso inicial de 355 kg, distribuídos num delineamento em blocos casualizados, com quatro tratamentos e sete repetições. O experimento teve duração de 99 dias, divididos em três períodos de 28 dias após 15 dias de adaptação. Quatro animais referência foram abatidos após o período de adaptação para estimativa do ganho de carcaça. Para estimativa da excreção fecal, utilizou-se a fibra em detergente ácido indigestível (FDAi) como indicador, após a incubação in situ por 240 horas. Observou-se menor (P0,05) pelas dietas. A conversão alimentar, o ganho de peso e o ganho de carcaça também não foram influenciados pelas dietas, registrando-se valores médios de 5,90; 1,49 kg/dia, e 0,91Kg/dia, respectivamente. Conclui-se, que a adição de melaço em pó na presença ou ausência de inoculante bacteriano à soja por ocasião da ensilagem, não afeta o padrão de fermentação ruminal, nem o desempenho de bovinos de corte, embora favoreça o consumo de nutrientes.Two experiments were carried out to evaluate the intake, total and partial nutrient digestibilities, pH and ruminal ammonia concentration (Experiment1), as well as the productive performance in beef cattle (Experiment 2) fed diets containing only soybean silage (SS) (control), soybean silage with microbial inoculant (SSI), soybean silage with inoculant and molasses (SSIM) and soybean silage with molasses (SSM). The inoculant used in the experiment was Sil All C4 (Alttech, Brazil). Molasses powder was used in the proportion of 2.5% in natural matter. The isonitrogen diets had 13% of crude protein. The roughage:concentrate ration was 70:30 on dry matter basis, with 40% of soybean silage and 30% of corn silage. In the first trial, four crossbred Holstein x Zebu rumen and abomasum fistulated animals, 230-kg average initial weight, were assigned to a 4 × 4 Latin square. Chromic oxide was used as marker to estimate digesta flow and fecal excretion. Nutrient intakes, expressed as kg/day, as well as its respective total, ruminal and intestinal apparent digestibilities were not influenced (P>0.05) by the diets. However, DM consumption, in percentage of live weight and g/kg0.75, was influenced (P0.05) of diet and collection time, or the interaction of these factors on ammonia and pH was found, with mean values of 11.91 and 6.45 mg/100 mL respectively. The passage rate was also not influenced by diets, with mean estimated value of 5.48% hour-1. In the Experiment 2, 32 non-castrated HxZ animals, 355-kg initial weight, were used in a randomized block design, with four treatments and seven repetitions. The experimental period was 99 days, divided into 3 shorter periods, after 15 days of adaptation. Four reference animals were sacrificed after the adaptation period in order to estimate carcass gain. Fecal excretion was estimated using indigestible acid detergent fiber (ADGi) as indicator, after in situ incubation for 240 hours. Lower nutrient intake (P0.05) by the diets. Food conversion, weight gain and carcass gain were not influenced by the diets, with mean values of 5.9; 1.49, and 0.91Kg/day respectively. It was concluded that the addition of molasses powder, with or without bacterial inoculant, to soybean at the time of ensilage does not affect the performance and the fermentation pattern in beef cattle, although it favors nutrient intake.Fundação de Amparo a Pesquisa do Estado de Minas Gerai

The chemical composition, fermentation profile, and microbial populations in tropical grass silages

The objective of this study was to evaluate the fermentation profile, chemical composition and microbial population and losses in the silages of signalgrass and Mombasa grass fertilized with the following levels of nitrogen (N): 0, 30, 60 and 90 kg/ha. The grasses were harvested at 70 days of regrowth, chopped and then ensiled in laboratory silos that had 20 kg of capacity and a snap-top cover and were fitted with Bunsen valves. Before ensiling, samples of the plants were used for the isolation and identification of lactic acid bacteria (LAB) in epiphytic microbiota. The design adopted was a 4 × 2 factorial arrangement, with four doses of N and two forage species, in a completely randomized design, with four replicates. The predominant species of LAB was Lactobacillus fermentum. The interaction between the N dose and forage species affected the dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and water soluble carbohydrates (WSC) of the silages. The pH values and gas losses were influenced only by the forage species, with higher values for the Mombasa grass. For the ammonia (NH3-N) levels and effluent losses, there was an effect of the interaction between the forage species and N doses, and the highest values of NH3-N and effluent losses were found in the Mombasa grass silage fertilized with 60 kg N/ha. Nitrogen fertilization reduces the levels of DM and WSC in the silages and also increases the levels of CP, NH3-N and effluent losses

The chemical composition, fermentation profile, and microbial populations in tropical grass silages

The objective of this study was to evaluate the fermentation profile, chemical composition and microbial population and losses in the silages of signalgrass and Mombasa grass fertilized with the following levels of nitrogen (N): 0, 30, 60 and 90 kg/ha. The grasses were harvested at 70 days of regrowth, chopped and then ensiled in laboratory silos that had 20 kg of capacity and a snap-top cover and were fitted with Bunsen valves. Before ensiling, samples of the plants were used for the isolation and identification of lactic acid bacteria (LAB) in epiphytic microbiota. The design adopted was a 4 × 2 factorial arrangement, with four doses of N and two forage species, in a completely randomized design, with four replicates. The predominant species of LAB was Lactobacillus fermentum. The interaction between the N dose and forage species affected the dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and water soluble carbohydrates (WSC) of the silages. The pH values and gas losses were influenced only by the forage species, with higher values for the Mombasa grass. For the ammonia (NH3-N) levels and effluent losses, there was an effect of the interaction between the forage species and N doses, and the highest values of NH3-N and effluent losses were found in the Mombasa grass silage fertilized with 60 kg N/ha. Nitrogen fertilization reduces the levels of DM and WSC in the silages and also increases the levels of CP, NH3-N and effluent losses

Fermentative characteristics and nutritional value of elephant grass silage added with dehydrated banana peel

The aim of this study was to evaluate the fermentative losses and nutritional value of elephant grass silages with the increasing of inclusion levels of dehydrated banana peel. The experiment was conducted in a completely randomized design, with six treatments and four replications, being the silage exclusively from elephant grass, and five levels of inclusion of banana peel to the elephant grass silage, as the following - 5; 10; 15; 20 and 25%, being added based on natural matter. The addition of the banana peel in the silage reduced linearly (p < 0.05) the pH, the ammoniacal nitrogen and the losses of the fermentative process. In addition, the inclusion of banana peel increased linearly (p < 0.05) the dry matter and non-fibrous carbohydrates. On the other hand, the neutral detergent fiber and the acid detergent fiber were linearly reduced with the inclusion of the banana peel (p < 0.05), but there was no change in the dry matter digestibility in situ. The inclusion of dehydrated banana peel in elephant grass silage reduces the losses of the fermentation process with more consistent results at the 25% inclusion level, however, it reduces the silage nutritional value due to fibrous and protein quality.