Sediment,nutrient and water losses by water erosion under agroforestry systems in the semi-arid region in northeastern Brazil     

Maria Ivanilda de Aguiar  Stoécio Malta Ferreira Maia  Francisco Alisson da Silva Xavier  Eduardo de Sá Mendonça  João Ambrósio Araújo Filho  Teógenes Senna de Oliveira 《Agroforestry Systems》2010,79(3):277-289

Inadequate soil management practices adopted in the Brazilian semi-arid region contribute to erosive processes. Agroforestry systems (AFs) have been considered an alternative to reduce water erosion. This study aimed to evaluate the impact of two alternatives AFs, a traditional and an intensive cropping system on the losses of sediments, water, organic carbon and nutrients caused by water erosion in comparison to the natural vegetation (caatinga) in a semi-arid region of northeastern Brazil. The agroecosystems studied were: agrosilvopasture (AGP) which consisted of an alley cropping system, cultivated with Leucaena leucocephala and maize, within an area composed by 22% of native trees (200 native trees per hectare) which was grazed during the dry season; silvopasture (SILV) that was composed by 38% of native trees (260 trees per hectare) with a stocking rate of 20 ewes during whole year; traditional agrosilvopasture (TRAG) being managed as following: total deforestation, burning of the residues, cropped with maize for 2 years (1998 and 1999) and fallow during 8–10 years; and intensive cropping (IC) system which was deforested and burned in 1997 followed by cultivation of maize from 1998 to 2002, and thereafter by a fallow period of 8–10 years similar to TRAG. Two areas of native forest (NF1, NF2) known as ‘caatinga’, used as grassland during the dry season and as a source of wood, were selected and used as reference of steady state in the comparative study in relation to the cultivated sites. Sediment and water losses as a result of erosion were collected during two rainy seasons, i.e. 2003 and 2004, and nutrients and organic carbon contents were determined. Soil samples were collected and organic carbon, pH in water, pH in KCl, water dispersible clay (WDC) and hydraulic conductivity (K₀) were measured. In 2003, sediment and water losses did not differ significantly among all treatments. However, in 2004, TRAG (0.70 Mg ha⁻¹) and NF1 (1.37 Mg ha⁻¹) showed the highest sediment losses, whereas TRAG and IC presented the highest water losses. On average, nutrients losses in cropped areas were lower than in natural vegetation (NF1, NF2). The alternative AFs (AGP, SILV) were efficient to reduce water erosion effects when compared to the most common agricultural practices adopted in the region, being highly recommended as sustainable technical alternatives for food production in the region.  相似文献   

Prevalence of Leptospira interrogans antibodies in free-ranging Tayassu pecari of the Southern Pantanal, Brazil, an ecosystem where wildlife and cattle interact     

Tatiana P. Tavares de Freitas  Alexine Keuroghlian  Donald P. Eaton  Emanuel Barbosa de Freitas  Aline Figueiredo  Luciano Nakazato  Jacqueline M. de Oliveira  Flávia Miranda  Rita Cassia S. Paes  Leticia A. R. Carneiro Monteiro  José Vergílio B. Lima  Aparecida A. da C. Neto  Valéria Dutra  Julio Cesar de Freitas 《Tropical animal health and production》2010,42(8):1695-1703

We surveyed a wild population of white-lipped peccaries (Tayassu pecari) in the Brazilian Pantanal for evidence of Leptospira interrogans. Serum samples from 71 free-ranging T. pecari were obtained between 2003 and 2005 in the southern Pantanal of Mato Grosso do Sul state. We used microscopic microagglutination to test for antibodies against 14 L. interrogans serovars (antibody titers ≥1:100 were considered seropositive). Seventy percent of captured animals tested positive for leptospirosis antibodies. Antibodies against icterohaemorrhagiae and autumnalis serovars were the most prevalent. We used log-linear analyses to test for associations among seropositivity, age class, and sex of captured animals. Seropositivity was strongly associated with animal age class, but independent of sex. Forty-six percent of animals less than 2 years old, 63% of adults during peak reproductive years, and 100% of the oldest age class were seropositive. A nonparametric multivariate procedure (MRPP) showed that the composition of serovar antibody types changed with age, and ANOVA models demonstrated that antibody titers increased with age, suggesting long-term exposure to a greater number and variety (i.e., serovar types) of L. interrogans infections. This study presents the first quantitative survey of antibodies against L. interrogans serovars in a T. pecari population of the Pantanal. The high prevalence of leptospirosis antibodies in free-ranging white-lipped peccaries and the potential impacts on reproduction and population dynamics emphasize the need for further studies investigating the roles of Pantanal wildlife and livestock in the transmission and maintenance of L. interrogans in the environment.  相似文献   

Subcutaneous embryonal rhabdomyosarcoma in a dog: cytologic, immunocytochemical, histologic, and ultrastructural features     

Avallone G  Pinto da Cunha N  Palmieri C  Della Salda L  Stefanello D  Roccabianca P  Caniatti M 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2010,39(4):499-504

Abstract: A subcutaneous mass on the left antebrachium of an 11‐year‐old intact female English Pointer dog was evaluated presurgically by cytologic examination and immunocytochemical staining. The sample consisted of discrete, variably sized, markedly pleomorphic neoplastic cells that expressed vimentin with diffuse cytoplasmic staining, desmin with focal paranuclear staining, and myoglobin with diffuse cytoplasmic staining, consistent with a diagnosis of rhabdomyosarcoma. Lymphocytic and histiocytic markers were negative. Aspirates of the enlarged ipsilateral prescapular lymph node were positive for metastatic disease. Surgical excision of the tumor and lymph node were followed by histologic and electron microscopic examination. Histomorphologic appearance of neoplastic cells from the mass and the lymph node paralleled cytologic findings; the histologic diagnosis was round cell variant of embryonal rhabdomyosarcoma. By ultrastructural evaluation, cells contained numerous mitochondria and masses of cytoplasmic tangled myofilaments, features typical of rhabdomyoblasts. The dog received doxorubicin (30 mg/m²) every 3 weeks for 5 treatments. Local recurrence developed 6 months after resection but was not treated. Despite a guarded prognosis and untreated local recurrence, the dog was still alive 18 months after surgery. Cytologic evaluation and immunocytochemical staining were pivotal for the presurgical diagnosis of rhabdomyosarcoma.  相似文献   

Repellent activity of plant-derived compounds against Amblyomma cajennense (Acari: Ixodidae) nymphs     

Sara Fernandes Soares  Lígia Miranda Ferreira Borges  Raquel de Sousa Braga  Lorena Lopes Ferreira  Carla Cristina Braz Louly  Leonice Manrique Faustino Tresvenzol  José Realino de Paula  Pedro Henrique Ferri 《Veterinary parasitology》2010

Repellence responses of Amblyomma cajennense nymphs to callicarpenal, intermedeol, Hyptis suaveolens essential oil, extract of Melia azedarach, Cymbopogon nardus, Spiranthera odoratissima, Chenopodium ambrosioides, Ageratum conyzoides, Mentha pulegium, Ruta graveolens, and Memora nodosa were studied. Among these the extract of C. nardus stood out because of the long-lasting repellence, maintaining, in the highest concentration, 35 h of protection against 90% of the nymphs. The essential oil of H. suaveolens and the extracts of C. ambrosioides and A. conyzoides showed good repellence index (66%) when applied in high concentrations. However, greater protection could be obtained at higher concentrations but with a shorter repellence time. Callicarpenal, intermedeol, extract of M. Pulegium, and M. nodosa leaves showed moderate repellence in high concentrations. Extracts from M. azedarach, R. graveolens, S. odoratissima, and M. nodosa roots showed little or no repellent effect. These results show that some plant extracts may represent a promising alternative in the control of infestations by A. cajennense.  相似文献   

Soil apparent electrical conductivity and geographically weighted regression for mapping soil     

J. M. Terrón  J. R. Marques da Silva  F. J. Moral  Alfonso García-Ferrer 《Precision Agriculture》2011,12(5):750-761

To resolve the spatial variation in soil properties intensively is expensive, but such knowledge is essential to manage the soil better and to achieve greater economic and environmental benefits. The objective of this study was to determine whether the soil apparent electrical conductivity (EC_a), alone or combined with other variables, is a useful alternative for providing detailed information on the soil in the Extremadura region of Spain. Apparent soil electrical conductivity was measured and geographically weighted regression was used to characterize the spatial variation in soil properties, which in turn can be used for soil management. This study shows that soil cation exchange capacity, calcium content, clay percentage and pH have a relatively strong spatial correlation with EC_a in the soil of the study area.  相似文献   

Calibration of a capacitance probe for measurement and mapping of dry matter yield in Mediterranean pastures     

João M. Serrano  José O. Peça  J. Marques da Silva  Shakib Shahidian 《Precision Agriculture》2011,12(6):860-875

The main objective of this study was to calibrate a commercial capacitance probe for measuring pasture dry matter yields under Mediterranean conditions. The standard method of assessing pasture biomass is based on cutting all the forage within a specified area and requires great effort and expense to collect enough samples to accurately represent a pasture. The field tests were carried out in 2007, 2008 and 2009 on different dates (phenological stages), and on five dairy farms, representing typical pastures in the region (grasses; legumes; and bio-diverse flora, mixture of grasses, legumes and others species). The linear regression techniques used in 2007 to relate the weight of the herbage (direct measurements) to the meter reading of capacitance (indirect measurements) led to high regression coefficients in grasses (R² = 0.90; P < 0.01) and heterogeneous botanical composition (R² = 0.87; P < 0.001) and moderate regression coefficient in legumes species (R² = 0.48; P < 0.05). The validation of the calibration equations in 2008 and 2009 in two sites showed RSME values of 130 kg ha⁻¹ in heterogeneous botanical composition and 456 kg ha⁻¹ in legumes. The results indicated that the capacitance probe together with a GPS receiver might support site-specific management of pastures which would be useful in large areas.  相似文献   

Essential oil of Aloysia triphylla as feed additive promotes growth of silver catfish (Rhamdia quelen)          下载免费PDF全文

C.C. Zeppenfeld  D.R. Hernández  J.J. Santinón  B.M. Heinzmann  M.A. da Cunha  D. Schmidt  B. Baldisserotto 《Aquaculture Nutrition》2016,22(4):933-940

This study examined the growth, gut morphology and occurrence of endocrine cells in the gastrointestinal tract of silver catfish (Rhamdia quelen) fed diets supplemented with essential oil (EO) extracted from Aloysia triphylla (0 – control, 0.25, 0.5, 1.0 and 2.0 mL EO per kg of diet) for 60 days. The group fed 2.0 mL EO per kg of diet showed better results after 60 days in growth, body weight, weight gain and specific growth rate. Histological and immunohistochemical analyses in the intestine demonstrated that height of folds was significantly higher in the control group and 0.25 mL EO compared to those fed 0.5 mL EO per kg of diet. There was a significant increase in the number of folds in fish fed 1.0 and 2.0 mL EO per kg of diet compared to control group. The enterocyte height was significantly lower in those fed 1.0 mL of EO group compared with 0.25 mL of EO per kg of diet. The number of cells that reacted to cholecystokinin and neuropeptide Y did not differ between groups. The addition of 2.0 mL EO per kg of diet increases silver catfish growth, and consequently, its use is recommended as a feed additive.  相似文献   

Crude glycerol in diets for Nile tilapia sex reversal (Oreochromis niloticus,Linnaeus 1758)          下载免费PDF全文

Fábio Meurer  Aldo Tovo Neto  Lilian Carolina Rosa da Silva  Luana Cagol  Marise Taise Theisen  Lilian Dena dos Santos 《Aquaculture Research》2016,47(8):2682-2685

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Yeast extract on growth,nutrient utilization and haemato‐immunological responses of Nile tilapia          下载免费PDF全文

Ricardo da Silva Berto  Gabriella do Vale Pereira  José Luiz Pedreira Mouriño  Maurício Laterça Martins  Débora Machado Fracalossi 《Aquaculture Research》2016,47(8):2650-2660

Dietary supplementation (0, 10, 20, 40, 60, 80 g kg^?1) of a nucleotide source (NuPro^®) was evaluated on growth, nutrient utilization, haemato‐immunological responses and resistance to experimental infection of Nile tilapia. Fish (2.63 ± 0.63 g) were fed experimental diets to satiation three times a day for 75 days. Feed intake increased linearly with increasing levels of NuPro^® promoting higher weight gain (P < 0.05). Survival, feed conversion and protein retention were not affected. Following the growth trial, fish were challenged with Aeromonas hydrophila by intraperitoneal injection. Survival and innate immune responses (phagocytosis and lysozyme activity) were not significantly affected. However, among the haematological variables, thrombocyte, leucocyte and monocyte counts increased linearly (P < 0.05). The indirect measurement of digestibility in juvenile Nile tilapia (122.32 ± 11 g) indicated a linear decrease in protein (1.41%), dry matter (5.72%) and energy (4.10%) digestibility coefficients as dietary supplementation increased (P < 0.05). NuPro^® showed to be a beneficial additive to be supplemented in diets for juvenile Nile tilapia, providing 32.8% increase in feed intake and 28.8% in weight gain, as well as in thrombocyte, leucocyte and monocyte counts in blood, possibly indicating a more efficient defence response in the highest dietary supplementation levels tested.  相似文献   

A review of the development and application of soybean‐based diets for Pacific white shrimp Litopenaeus vannamei     

D. Sookying  D.A. Davis  F. Soller Dias da Silva 《Aquaculture Nutrition》2013,19(4):441-448

The production of the Pacific white shrimp (Litopenaeus vannamei) has expanded to the point of being the most widely cultured species of shrimp. One of the advantages of this species is its acceptance of a wide variety of feed formulations including plant‐based feeds. Given the increases in ingredient costs, particularly fish meal, there is considerable interest in the use of alternative feed formulations for cultured species. Given that soybean meal is one of the most widely available protein sources for which production can be expanded, the move to soy‐based diets is inevitable. The successful use of alternative feed ingredients for shrimp production depends on a number of factors. This paper summarizes studies regarding the move towards high soy diets concerning manipulation of ingredients and nutrient profiles to maintain balanced feed formulations.  相似文献