Índice de acidez del aceite de pez en la nutrición de alevines de pacú Piaractus mesopotamicus

The aim of this study was to evaluate the effects of fish oil acidity on the growth of pacu (Piaractus mesopotamicus) juveniles. Two hundred juveniles with 10.53±0.65 g of weight and 8.74±0.13 cm of total length, were distributed in a totally randomized design in 20, 0.15 m3 meshmade tanks placed in a 25 m3 holding tank. Extruded commercial diets sprayed with soybean oil (control) with acidity index of 0.24 and fish oil with acidity index of 1.48, 6.40 and 9.85 were used. The fish were fed four times a day until apparent satiety. Productive performance, centesimal composition and blood biochemistry were analysed. At the end of the feeding period none of the analyzed parameters was affected by the use of acidified fish oil. Therefore, fish oil may be supplied to the pacu juveniles regardless of their pH.

Formas de aplicación de zinc para las plantas de maíz que crecen en Oxisol: Efectos sobre el suelo, la nutrición de las plantas y la productividad

The way of applying zinc can influence the zinc uptake and productivity of crops, especially cereals that have high demand for this nutrient. The aim of this study is to evaluate methods of Zn application on soil, nutritional status and productivity of maize. For this, an experiment was undertaken at FCAV/UNESP, Jaboticabal-SP, in Oxisol clay (DTPA on Zn: 0.5 mg dm-3) with maize (hybrid Simple Impact), from December through May 2009. Nine treatments with three doses of Zn in soil banded application (in furrows) and three doses of Zn by incorporation in soil (0-20 cm depth), foliar application, seed application and control (no Zn). The treatments were arranged in a randomized block design with four replications. Regardless of the method, Zn application promoted higher contents of this micronutrient in soil and higher accumulation in the shoots as well as increasing Zn in the maize grain. However, it did not affect the nutritional status and yield of the maize. The Zn application in the soil resulted in a greater Zn uptake by plants and maize yield, compared to Zn application in the plant by seed or foliar.