939 resultados para Grass-cutting ants
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The survival of infective larvae (L3) of Trichostrongylus colubriformis was evaluated on Brachiaria, Coast-cross and Aruana forage grasses. Feces of sheep parasitized exclusively by T. colubriformis were deposited in winter and spring on experimental plots whose grasses were cut at two heights: 5 cm and 30 cm. One, two, four, eight, 12 and 16 weeks after depositing the feces, fecal and forage samples were collected for the retrieval and quantification of L3. Retrieval of L3 from feces and forage was negligible in winter due to the dry weather, although a few larvae were retrieved in the last larval collections. However, L3 retrieval from fecal samples was greater in spring, especially two weeks after feces were deposited on 30 cm high grasses. At this time, the L3 retrieval rate from the three forage grasses differed significantly (P < 0.05), with Aruana grass showing the highest average L3 retrieval rate, followed by Coast-cross and Brachiaria. In conclusion, the winter drought proved very unfavorable for the presence of L3 in the environment, and the microclimate of Aruana pastureland was generally the most favorable for the retrieval of infective larvae.
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The use of legumes intercropped with forage in the Brazilian savannah (Cerrado) region is an alternative to reverse the process of pasture degradation. The natural phosphorus deficiency in this region and the high retention capacity of this nutrient in the soil are factors that directly affect the sustainability of the production system. The objective of this study was to evaluate the effect of a phosphate with medium solubility (Arad) compared to more soluble sources such as triple superphosphate and mono-ammonium phosphate, on the formation and maintenance of pastures of Andropogon gayanus with or without the introduction of Stylosantes guianensis in pasture already established in the Brazilian savannah. Two experiments were carried out under field conditions in an Oxisol using a randomized block design with split plots, plots with two sources of phosphorus (Arad and super-triple or MAP) and subplots with different levels of phosphorus. The study showed that andropogon grass, even though characterised as forage requiring low fertilization, responded to increased fertilization, especially with the use of more soluble sources of P at planting. From the second year on, with the introduction of Stylosantes guianensis, verified effects were seen on legumes in their efficiency of utilization of residual fertilization from the first year; however, this didn't affect legume dry matter production resulting from the P sources used for the andropogon grass. The mixed stands of andropogon grass and Stylosantes guianensis made it more advantageous to increase the P sources using phosphate fertilizer with lower solubility (Arad), when compared to MAP.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This study aimed to evaluate feed preference and control efficacy of grass carp (Ctenopharyngodon idella) on the aquatic macrophytes Ceratophyllum demersum, Egeria densa and Egeria najas. An experiment was carried out at mesocosms conditions with 2,000 liters capacity and water residence time of 2.8 days. C. demersum, E. densa e E. najas biomasses were offered individually with sixty g and coupled in similar quantities of 30 g of each species, evaluated during 81 days, envolving 6 treatments. (1 - C. demersum, 2 - E. najas, 3 - E. densa, 4 - C. demersum + E. najas, 5 - C. demersum + E. densa and 6 - E. najas + E. densa). When offered individually, E. najas and C. demersum presented the same predation rate by grass carp, which was higher than E. densa predation rate. When plants were tested in pairs, the order of feed preference was C. demersum > E. najas > E. densa. E. najas and C. demersum percentage control ranged from 73 to 83%. No relation between biomass consumption and grass carp body weight gain was observed, probably due to differences in nutritional quality among macrophyte species according to fish necessities. Therefore, it is concluded that the use of grass carp is one excellent technique to control submersed macrophytes in Brazil.
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Este trabalho foi conduzido para avaliar o valor nutritivo de silagens de capim-elefante (Pennisetum purpureum, Schum.) com 0, 4, 8, 12 e 16% de pedúnculo de caju (Anacardium occidentale L.) desidratado, com base na matéria natural. Utilizou-se o delineamento inteiramente casualizado com quatro repetições. Como silos experimentais, foram utilizados tambores plásticos de 210 L. Determinaram-se a composição nutricional, os valores de pH e os teores de nitrogênio amoniacal, ácido lático, acético, propiônico e butírico. A inclusão de pedúnculo de caju desidratado na ensilagem de capim-elefante promoveu aumento das concentrações de matéria seca (MS), proteína bruta (PB), extrato etéreo (EE), carboidratos não-fibrosos (CNF), nitrogênio insolúvel em detergente neutro (NIDN, % do N total), nitrogênio insolúvel em detergente ácido (NIDA, % do N total), pH e ácidos lático e propiônico. Por outro lado, os teores de FDN, FDA, hemicelulose, N-NH3 (% do N total) e ácido butírico diminuíram de forma linear conforme aumentaram os níveis do subproduto na ensilagem. O pedúnculo de caju desidratado não influenciou os teores de carboidratos totais e ácido acético das silagens. Esse subproduto pode ser ensilado com o capim-elefante até o nível de 16%, uma vez que aumenta os teores de PB e CNF e reduz os teores de FDN e FDA, melhorando o padrão de fermentação das silagens.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Gaseous losses are the main factors affecting the efficiency of nitrogenous fertilizers in pastures. To evaluate NH3-N volatilization losses in Tanzania grass fertilized with urea in autumn, spring and summer, a completely randomized design with repeated measurements over time and fifteen replicates was used. Plots were represented by urea levels (50; 100 and 150 kg ha-1 N) and subplots by time after fertilization (1; 2; 3; 6; 9; 12 and 15 days). The interaction between fertilization leveland time after urea application was significant for the accumulated NH3-N volatilization. Urea application leads to higher percentage N losses in the first three days after application. The average cumulative NH3- N loss for the three occasions (different seasons of the year) was 28%, 20% and 16% of N applied for fertilizer doses of 50; 100 and 150 kg ha-1 of N, respectively. The season of the year influenced NH3-N loss pattern and volume, with the lowest values recorded in spring, followed by summer and autumn. The cumulative NH3-N volatilization loss varies from 78 to 90% up to the third day after application of the total NNH3 loss.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In crop-livestock integration systems the presence of both grass roots in the soil and straw on the surface can temporarily immobilize nitrogen. This study examined the persistence of grass residues in the system as well as their effects on cotton response to N when grown after Congo grass (Brachiaria ruziziensis, Syn. Urochloa ruziziensis). Congo grass was grown in pots with soil. Next, cotton was grown in the same pots without residues, with whole plant residues (Congo grass roots and shoots) or root residues (grass roots) and fertilized with N as ammonium nitrate. Congo grass and cotton roots were separated using stable carbon isotope fractioning. Congo grass roots showed higher C/N ratio than shoots, losing 14% of its mass after 45 days and increasing soil N immobilization. The lower N availability resulted in N deficient and shorter cotton plants with lower dry matter yields. Nevertheless, the application of 80 to 120 mg kg-1 of N compensated the immobilization by the soil microorganisms, allowing cotton to show normal growth. When Congo grass is present in the cropping system, the effects of the decaying roots on soil N dynamics and availability are more important than those of the straw left on the soil surface.
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Annually, mature colonies of Atta ants produce winged males and females, where leave the colony in which they were produced to form new colonies and thus continue the species perpetuation. The foundation of Atta spp. colonies always involves high queen effort, solely responsible for growing the fungus and the care with itself and its offspring. During the foundation there is consumption of body reserves. This study investigated how the environment influences the development of newly founded colonies of leaf cutting ant, Atta sexdens rubropilosa. Therefore, it was compared field colonies collected five months after the nuptial flight and colonies maintained in the laboratory since the nuptial flight. It was analyzed the weight and size of the population (number of workers, larvae, pupae and eggs), the workers size, the volume and weight of the fungus garden and queen effort for the nest foundation (lipid content and weight of queens). In comparison to the field colonies, the laboratory colonies showed higher values in the weight and size of population, the volume and weight of the fungus garden. Measures of workers by class size did not vary between colonies from field and laboratory. The queen effort for nest foundation was higher in field colonies, which showed a lower percentage of fat and lower weight compared to laboratory colonies. These results show that the environment has a strong influence on the colonies development during the foundation, as well as on the physiological status of the queens, and therefore the survival, development and success of the colony, it is a reflection of the queen efforts and of the environment conditions.
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Mycelial growth strains of POS 98/38, POS 09/100, POS 09/101, and POS 09/102 of Pleurotus ostreatus were evaluated in culture media with various compositions based on extracts of substrates formulated with sugar cane bagasse together with straws and grasses, and with or without nitrogen supplementation. The evaluation was performed during incubation regularly with a ruler graduated in millimeters until total colonization of the culture medium contained in Petri dishes. The statistical model explaining the kinetics of mycelial growth of mushroom strains of P. ostreatus as a deterministic component has an exponential Gompertz function. The results show that the culture medium with sugar cane straw and brizantha grass (supplemented) showed the highest rates of mycelial growth, regardless of strain used compared to wheat straw-based culture media with had the lowest velocities of growth, regardless of supplementation and strains studied.
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Handwriting is a tool for communication often untaught that has effects on learning and long-term development for students of the future. Handwriting used to be needed in order to function in society, however, today that skill is no longer needed. New technology, current teaching methods and societal needs have caused handwriting to be overlooked in many school districts. Classrooms are overwhelmed with information and many schools are simply running out of time to teach cursive, therefore no longer making it a priority. Handwriting is a perceptual motor skill requiring higher cognitive thinking, something that most primary school children find difficult, yet it is still needed in the school curriculum and provides a stable foundation for students of the future. The questions to be addressed by my research are to examine the factors that have led to the demise of cursive writing in elementary schools. I will research the complex issues that have contributed to the decline of cursive handwriting. This will include my investigation into the factors that technology has played, along with societal needs. I will interview preservice teachers, those students in college preparing to become teachers, and try to understand where the importance for teaching handwriting started and ended. By the end of my research I want to have constructed a timeline of events to explain the demise of this needed skill. My methodology for this research will be to gather information from various primary and secondary literature review sources. I want to understand when cursive started to disappear from the curriculum and why.
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It is marvelously fitting that we gather here in Nebraska City on this lovely fall afternoon to officially celebrate this wonderful new center. Fall is a traditional-time of harvest in Nebraska, and for many of us there is a deep and abiding satisfaction in bringing a good crop to fruition. Apple harvests at Nebraska City orchards long have brought visitors here each year for fresh fruit and cider.