Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Dry matter. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Bird Extinctions in Atlantic Forest Fragments of the Viçosa Region, Southeastern Brazil

Abstract: : We studied the conservation status of Atlantic forest birds in 43 forest fragments ranging in size from 1 to 384 ha in the Vicosa region of southeastern Brazil. We compared data from 15 years of field work with historical records from the region, mainly originating from specimens collected by Joao Moojen during the 1930s. We used published studies associated with museum data and current field work to assess the decline of forest birds during the last 70 years and to relate their disappearance to forest fragmentation and destruction. At least 28 bird species have become locally extinct, 43 are critically endangered, and 25 are vulnerable, representing 60.7% of the original forest bird community known to exist in the region. Vulnerability to fragmentation differed among guilds, forest strata, and endemicity status. Birds that feed on fruit and seeds, and those that feed on insects, were more threatened than omnivores and carnivores. Nectarivorous species were less threatened than other guilds. Moreover, terrestrial and understory birds or birds using only one forest stratum also were more likely to have been threatened. Finally, Atlantic forest endemics were more likely to have become extinct than nonendemic species. In general, sensitivity to environmental disturbance at the local level was similar to the predicted vulnerability to regional disturbance derived from the literature. Our results indicate that a serious decline of Atlantic forest birds is underway and that many other species of birds, not previously recognized as threatened, are of conservation concern. Resumen: Estudiamos el estado de conservacion de aves de bosque atlantico en 43 fragmentos de 1 a 384 ha en la Region Vicosa, al sureste de Brasil. Comparamos datos de 15 anos de trabajo de campo con registros historicos de la region, principalmente de especimenes colectados por Joao Moojen durante la decada de los anos 30. Utilizamos estudios publicados asociados con datos de museo y de trabajo de campo reciente para analizar la disminuicion de aves de bosque durante los ultimos 70 anos y para relacionar su desaparicion con la fragmentacion y destruccion del bosque. Se han extinguido por lo menos 28 especies de aves localmente, 43 estan criticamente en peligro y 25 son vulnerables, lo cual representa el 60,7% de la comunidad de aves de bosque conocida para la region. La vulnerabilidad a la fragmentacion fue diferente entre gremios, estratos de bosque y estado de endemismo. Las aves que se alimentan de frutos y semillas y aquellas que se alimentan de insectos estan mas amenazadas que las omnivoras y carnivoras. Las especies nectarivoras estan menos amenazadas que otros gremios. Mas aun, las aves terrestres y de sotobosque o las que utilizan solo un estrato del bosque tambien tienen mayor probabilidad de estar amenazadas. Finalmente, las aves endemicas al bosque atlantico tienen mayor probabilidad de extincion que las no endemicas. En general, la sensibilidad a la perturbacion ambiental a nivel local fue similar a la vulnerabilidad a la perturbacion regional predicha, derivada de la bibliografia. Nuestros resultados indican que existe una seria declinacion de aves de bosque atlantico y que muchas otras especies de aves, no reconocidas como amenazadas previamente, son de interes para la conservacion.

World Management of Geminiviruses.

Abstract: Management of geminiviruses is a worldwide challenge because of the widespread distribution of economically important diseases caused by these viruses. Regardless of the type of agriculture, management is most effective with an integrated pest management (IPM) approach that involves measures before, during, and after the growing season. This includes starting with resistant cultivars and virus- and vector-free transplants and propagative plants. For high value vegetables, protected culture (e.g., greenhouses and screenhouses) allows for effective management but is limited owing to high cost. Protection of young plants in open fields is provided by row covers, but other measures are typically required. Measures that are used for crops in open fields include roguing infected plants and insect vector management. Application of insecticide to manage vectors (whiteflies and leafhoppers) is the most widely used measure but can cause undesirable environmental and human health issues. For annual crops, these measures can be more effective when combined with host-free periods of two to three months. Finally, given the great diversity of the viruses, their insect vectors, and the crops affected, IPM approaches need to be based on the biology and ecology of the virus and vector and the crop production system. Here, we present the general measures that can be used in an IPM program for geminivirus diseases, specific case studies, and future challenges.

Evaluation of ruminal degradation profiles of forages using bags made from different textiles

Abstract: The objective of this study was to evaluate the in situ degradation profiles of dry matter (DM) and neutral detergent fiber (NDF) of different forages using nylon (50 µm), F57 (Ankom®) and non-woven textile (NWT - 100 g/m2) bags. Eight forage samples were used: sugarcane, corn silage, elephant grass cut at 50 and 250 days of regrowth, corn straw, signal grass hay, coast cross hay, and fresh alfalfa. Samples were incubated for 0, 3, 6, 12, 18, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, and 312 hours. Two bags of each textile were used at each incubation time, totaling 768 bags, using two crossbred Holstein × Zebu steers fitted with ruminal canullae. There was difference in the common rate of lag and degradation (λ) of DM for all forages, except for sugarcane. In general, higher λ estimates were obtained using nylon, followed by NWT and F57. Concerning NDF degradation profiles, differences in λ were observed for all forages. Greater estimates were obtained using nylon. Degradation profiles of DM and NDF must not be evaluated using F57 and NWT. These textiles underestimate the degradation rate due to constraints regarding exchange between bags' content and rumen environment.

Intake and digestibility in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds

Abstract: The objective of this study was to evaluate the effects of supplementation with nitrogenous compounds on intake, digestibility, and rumen microbial synthesis in cattle fed low-quality tropical forage. Five crossbred heifers, averaging 209 kg and fitted with ruminal fistulla, were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 5.08%, as dry matter (DM) basis. The five treatments were defined according to the increasing level of CP in the diet (0, 3, 5, 7, and 9 percentile points above the forage CP level). The supplement consisted of the following nitrogen sources: urea, ammonium sulfate and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5.28, 8.08, 9.82, 11.87, and 13.63% on DM basis. The intakes of DM, organic matter (OM), and neutral detergent fiber (NDF) showed a quadratic response according to CP levels in the diet, with maximum responses at 10.83%, 10.78%, and 10.37% CP, respectively. The digestibility coefficients of OM and NDF showed a linear-response-plateau response according to CP levels, with the plateau beginning (maximum response) at 7.93% and 7.55% CP, respectively. The average daily concentration of rumen ammonia nitrogen (RAN) was positively related with CP levels. The RAN estimate associated with the maximum DM intake was 15.33 mg/dL. It was observed that intestinal flow of microbial nitrogenous compounds and nitrogen intake became equivalent to each other at 7.13% of CP.