Garrido M.S.,Colegiado de Engineering Agricola |
De Carvalho P.G.S.,Colegiado de Engineering Agricola |
Da Rocha L.G.,CODEVASF |
Campeche D.F.B.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria
Engenharia Agricola | Year: 2014
This study aimed to apply mathematical models to the growth of Nile tilapia (Oreochromis niloticus) reared in net cages in the lower São Francisco basin and choose the model(s) that best represents the conditions of rearing for the region. Nonlinear models of Brody, Bertalanffy, Logistic, Gompertz, and Richards were tested. The models were adjusted to the series of weight for age according to the methods of Gauss, Newton, Gradiente and Marquardt. It was used the procedure "NLIN" of the System SAS® (2003) to obtain estimates of the parameters from the available data. The best adjustment of the data were performed by the Bertalanffy, Gompertz and Logistic models which are equivalent to explain the growth of the animals up to 270 days of rearing. From the commercial point of view, it is recommended that commercialization of tilapia from at least 600 g, which is estimated in the Bertalanffy, Gompertz and Logistic models for creating over 183, 181 and 184 days, and up to 1 Kg of mass, it is suggested the suspension of the rearing up to 244, 244 and 243 days, respectively.
Souza R.C.,Federal University of Vale do Sao Francisco |
Campeche D.F.B.,Pesquisadora Embrapa Semiarido |
Campos R.M.L.,Federal University of Vale do Sao Francisco |
Figueiredo R.A.C.R.,CODEVASF |
Melo J.F.B.,Federal University of Vale do Sao Francisco
Arquivo Brasileiro de Medicina Veterinaria e Zootecnia | Year: 2014
The aim of this research was to assess how often food promotes better performance in tambaqui. We tested four food frequencies (two, four, six and eight times a day) at regular intervals. Tambaqui fingerlings with initial weight of 15.74±0.28g were stocked in 16 transparent glass tanks with a capacity of 70L of usable volume in a completely randomized design with four treatments and four replications. The feeding period was thirty days and a commercial diet containing 45% crude protein for omnivorous fish and a feeding rate of 6% of the total biomass of fish for each experimental unit was used. The average results of pH, temperature °C and electrical conductivity mS/cm for morning and afternoon were respectively 6.91 and 6.96; 25.85 and 27.69; 0.65 and 0.65. We evaluated the performance indices: weight gain, feed conversion, specific growth rate, survival, and also blood glucose. No significant differences were detected for the variables studied. It is recommended that the frequency of feeding be 2 times a day for tambaqui, mainly to minimize labor.
da Silva A.M.,Sao Paulo State University |
Braga Alves C.,Sao Paulo State University |
IForest | Year: 2010
The present paper reports the assessment of the vegetation occupancy rate of the roadside, through analysis of aerial photographs. Using such value the potential of these areas to be employed as carbon (C) sinks was also assessed. Moreover, for the areas suitable for afforestation, the potential for carbon sequestration was estimated considering different species of vegetation, both native (scenario 1) and exotic (formed by Pinus sp. and Eucalyptus sp. - scenario 2). The study was carried out through GIS techniques and two regions were considered. A set of equations was used to estimate the rate of occupancy over the study areas, as well as amounts of fixed C under the above scenarios. The average occupancy rate was 0.06%. The simulation showed a higher potential for C sequestration in scenario 2, being the estimated amounts of CO2 sequestered from the atmosphere per km of roadside: 131 tons of CO2 km-1 of highway to native species and 655 tons of CO2 km-1 of highway for exotic species (over period of 10 years for both estimates). If we consider the whole road network of the São Paulo State (approximately 190 000 km) and that a considerable part of this road work is suitable to receive this kind of service, it is possible to predict the very high potential for C sequestration if managers and planners consider roadside as area for afforestation. © iForest-Biogeosciences and Forestry.
Souza R.C.,Federal University of Vale do Sao Francisco |
Melo J.F.B.,Federal University of Vale do Sao Francisco |
Nogueira Filho R.M.,Bahia State University |
Campeche D.F.B.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuaria |
Archivos de Zootecnia | Year: 2013
Mango meal with peel was evaluated as carbohydrate source in substitution of corn, for tilapia juvenile growth and carcass composition. There were used 180 fish (4,69 ± 0,06 g) in 12 tanks of 500 L, fed three times a day (6 % of live weight), in a water recirculating system with biofilter. Four diets were evaluated with different mango meal concentrations T1= diet with 30 % of corn; and T2, T3 and T4 in which 33, 66, and 100 % of corn was replaced by mango meal. All of the treatments had three repetitions. At the end of 45 days performance was evaluated (final weight, weight gain; specific growth rate, feed consumption, apparent feed conversion rate, carcass yield, survival) and chemical carcass composition. The levels of mango meal substitution by corn meal affected all the variables analyzed from level 33 % (p<0,05), with the exception of survival and carcass yield (p>0,05). Carcass chemical composition values were changed except for ash. Mango meal in substitution for corn may be used until the level of 33 % in Nile tilapia feed without damage for growth performance and carcass chemical composition.
Hydrological simulation in a watershed with predominance of Oxisol in the upper Grande river region, MG - Brazil [Simulação hidrológica em uma bacia hidrográfica representativa dos latossolos na região alto rio grande, MG]
Andrade M.A.,CODEVASF |
de Mello C.R.,Federal University of Lavras |
Beskow S.,Federal University of Pelotas
Revista Brasileira de Engenharia Agricola e Ambiental | Year: 2012
Hydrological simulation has been considered an important tool applied to support water resources management in watersheds. The studied watershed is located in the Upper Grande river region in southern Minas Gerais State, draining an area of 32 km2 towards the Camargos Hydroelectric Power Plant Reservoir (UHE - Camargos/CEMIG). In this context, this study aimed to calibrate and validate the SWAT model (Soil and Water Assessment Tool) for assessing quantitatively the stream flow in the Jaguara Creek Watershed (JCW). For that, SWAT model requires land-use and soil maps and digital elevation model, besides historical series related to meteorological and hydrological data sets. January 1, 2006 to August 31, 2009 was the period used for the above-mentioned historical series. The performance of SWAT was measured through Nash-Sutcliffe coefficient (CNS) which was 0.66 and 0.87 for calibration and validation, respectively. Comparing CNS results found in this study to the ones established in a SWAT model performance classification, it was found that such model can be used to evaluate the hydrological behavior in the JCW, which is a watershed representative of the Oxisol in the Upper Grande river region in southern Minas Gerais State.