Objective. To evaluate the nutritional composition of duckweed (DW) (Lemna minor) and water hyacinth (WH) (Eichhornia crassipes) and its effect on the apparent digestibility of dry matter (%, ADDM), apparent digestibility of crude protein (%, ADCP) and the apparent digestibility of the crude lipid (%, ADCL) in the nutrition of tilapia (Oreochromis niloticus). Material and methods. The DW and WH were used to formulate nine isoproteic (32.47%), isolipidic (5.46%) and isoenergetic (16.45 MJ kg-1) diets, with three replicates and 15 male tilapia (36.36± 1.16 g) per repetition: 0% (T0); 10% (T10); 15% (T15); 20% (T20) and 25% (T25), respectively random. A principal component analysis (PCA) was applied. Results. The crude protein (%) of the WH and the DW, were 21.72% and 27.37% (p˂0.05), respectively. Fish fed with WH and DW, up to 10 and 15% inclusion in the diet, respectively, did not show significant differences (p>0.05) for ADDM. However, for ADCP and ADCL, up to 15 and 20%, respectively, significant differences (p>0.05) were not observed. Conclusions. Water hyacinth and duckweed meals were an alternative vegetable protein source, which can partially replace soybean meal and cornmeal in tilapia diets. The PCA suggests that the control diet, 10% WH, 10-15% DW, showed the best results in terms of the apparent digestibility of the nutrients. | Objetivo. Evaluar la composición nutritiva de la lenteja de agua (LA) (Lemna minor) y jacinto de agua (JA) (Eichhornia crassipes) y su efecto en la digestibilidad aparente de la materia seca (%, DAMS), digestibilidad aparente de la proteína cruda (%, DAPC) y la digestibilidad aparente de la grasa cruda (%, DAGC) en la nutrición de la tilapia (Oreochromis niloticus). Materiales y métodos. La LA y el JA se utilizaron para formular nueve dietas isoproteicas (32.47%), isolipídicas (5.46%) e isoenergéticas (16.45 MJ kg-1), con tres repeticiones y 15 tilapias machos (36.36±1.16 g) por repetición: 0% (T0); 10% (T10); 15% (T15); 20% (T20) y 25% (T25), respectivamente al azar. Se aplicó un análisis de componentes principales (PCA). Resultados. La PC del JA y la LA, fue 21.72% y 27.37% (p˂0.05), respectivamente. Los peces alimentados con JA y LA, hasta 10 y 15% de inclusión en la dieta respectivamente, no mostraron diferencias significativas (p>0.05) para la DAMS, aunque para la DAPC y DAGC, hasta 15 y 20%, respectivamente, no se observó diferencias significativas (p>0.05). Conclusiones. Las harinas de jacinto de agua y lenteja de agua, son fuente de proteína vegetal alternativa, que pueden sustituir parcialmente la soya y maíz en dietas para la tilapia (O. niloticus). El PCA sugiere que la dieta de control, 10% JA, 10-15% LA, mostraron los mejores resultados en términos de digestibilidad aparente de los nutrientes.

A total of 300 Centropomus undecimalis juveniles, with an average initial weight of 3.16 ± 0.28 g and average total length of 7.17 ± 0.22 cm, were reared for eight weeks using a recirculating system to determine the dietary protein requirement for their growth and survival. The e ect of ve experimental diets containing 40, 45, 50, 55 and 60% total protein content and two salinities (brackish water, BW at 5 UPS and marine water, MW at 36 UPS) were assessed. Fish were fed ve times per day at 2.5% of total biomass. All treatments were performed in triplicate, recording the individual weight and total length every 15 d, while weight gain and daily growth rate were recorded at the end of the experiment. Mean weight increased proportionally as protein content increased, with the greatest growth occurring with a 60% protein diet for sh reared in brackish water, and 55% for sh in marine water. We consider that the protein requirement in C. undecimalis juveniles is high; in addition, it differs depending on the salinity, which may be due to the higher energy expenditure derived from the processes of osmoregulation in fish reared in marine water.

A total of 300 Centropomus undecimalis juveniles, with an average initial weight of 3.16 ± 0.28 g and average total length of 7.17 ± 0.22 cm, were reared for eight weeks using a recirculating system to determine the dietary protein requirement for their growth and survival. The e ect of ve experimental diets containing 40, 45, 50, 55 and 60% total protein content and two salinities (brackish water, BW at 5 UPS and marine water, MW at 36 UPS) were assessed. Fish were fed ve times per day at 2.5% of total biomass. All treatments were performed in triplicate, recording the individual weight and total length every 15 d, while weight gain and daily growth rate were recorded at the end of the experiment. Mean weight increased proportionally as protein content increased, with the greatest growth occurring with a 60% protein diet for sh reared in brackish water, and 55% for sh in marine water. We consider that the protein requirement in C. undecimalis juveniles is high; in addition, it differs depending on the salinity, which may be due to the higher energy expenditure derived from the processes of osmoregulation in fish reared in marine water.

A soja apresenta elevada demanda por nitrogênio devido ao alto teor protéico dos grãos, de cerca de 40%, o que a torna de grande importância econômica. Este trabalho teve como objetivo determinar o efeito da disponibilidade hídrica e arranjo de plantas sobre a qualidade dos grãos de duas cultivares de soja, no ano agrícola 1998/99, na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul (EEA/UFRGS), em Eldorado do Sul, RS. O delineamento experimental foi de blocos ao acaso, em parcelas sub-subdivididas, com quatro repetições. Foram testados dois regimes hídricos (irrigado e não irrigado), duas cultivares (BRS 137 e BRS 138) e três espaçamentos entre linhas (20cm, 40cm e 20-40cm em linhas pareadas). Avaliou-se o teor de N nas folhas durante a ontogenia, os teores de proteína e óleo, bem como o tamanho e peso dos grãos. O rendimento médio de grãos foi de 3360kg ha-1. A irrigação proporcionou aumento de 1101kg ha-1 (39%), decorrente do aumento no teor de N nas folhas, tamanho e peso dos grãos. A cultivar BRS 137 rendeu 535kg ha-1 (17%) a mais do que a BRS 138; os grãos eram de maior tamanho, peso e teor de proteína. No final do período reprodutivo, o teor de N nas folhas foi mais elevado em 20cm e 40cm, resultando em teor de proteína e rendimento de grãos 18 e 13% mais elevado do que 20-40cm em linhas pareadas, respectivamente. O teor de óleo nos grãos não foi alterado em função dos tratamentos. | The soybean is a crop with high demand for nitrogen (N) due to the grain protein content of about 40%. Because of the high protein, soybean is of great economic importance. The present study had its objectives to determine the effect of water availability and soybean plant arrangement on grain quality of two cultivars. With this objective, an experiment was performed during the 1998/99 growing season, in the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), Eldorado do Sul, RS. The treatments were arranged in a randomized complete-block in a split split-plot design, with four replications. Two water availability (irrigated and not irrigated), two cultivars (BRS 137 and BRS 138) and three row spacings (20cm, 40cm and 20-40cm in skip row) were tested. The leaf N content was evaluated during crop growth, and the protein and oil content, as well as the size and weight of the grains, at the harvest. The average grain yield was of 3360kg ha-1. The irrigation increased grain yield by 1101kg ha-1 (39%), due to the increase in leaf N, size and weight of the grain. The yield of the cultivar BRS 137 was 535kg ha-1 (17%) greater, as well as it produced grains with larger size, weight and protein content than BRS 138. In the late reproductive stage, leaf N was higer in 20cm and 40cm, what resulted in larger protein content and grain yield 18 and 13% higher, compared to 20-40 cm in skip row, respectively. The grain oil content was not altered by the treatments

A amônia, produto de excreção dos peixes, é tóxica para organismos aquáticos. O objetivo deste trabalho foi quantificar taxas de excreção diária de amônia em tambaqui (Colossoma macropomum), principal espécie criada na Amazônia, que podem variar de acordo com a temperatura da água e a massa dos peixes. As taxas de excreção foram determinadas a cada 2 horas por um período de 24 horas e os resultados analisados por uma regressão linear múltipla. O tambaqui apresentou de dois a cinco picos de atividade de excreção durante 24 horas, caracterizados por rápidos aumentos de até dez vezes na taxa horária de excreção. O modelo desenvolvido pela regressão linear múltipla explicou 95,2% da taxa diária de excreção de amônia, que aumentou com a massa do peixe, mas diminuiu com o aumento da temperatura da água. | Ammonia, an excretion product of fish, is toxic to aquatic organisms. The objective of this study was to account daily ammonia excretion rates of tambaqui (Colossoma macropomum), the main fish species of the Amazonia related to water temperature and fish mass. Ammonia excretion rates were measured every two hours during a 24-hour period and results were evaluated by a multiple linear regression. Tambaqui presented two to five excretion peaks during the 24-hour period, reaching up to ten times the mean excretion rates. The model developed by the multiple linear regression explained 95.2% of the daily ammonia excretion rates, which increased according to fish mass and decreased when water temperature increased.

"Se realizó un estudio para evaluar el efecto de los niveles de proteína y energía sobre el crecimiento, supervivencia y la respuesta antioxidante de la enzima superóxido dismutasa (SOD) en juveniles de Cherax quadricarinatus. El experimento incluyó seis dietas prácticas con tres niveles de proteína cruda (28, 35 y 40%) y dos niveles de energía (~18 y 20 kJ·g–1). El grupo control fue alimentado con alimento comercial para camarón. La actividad SOD más alta (34.8 U·mg–1 prot.) se presentó en juveniles alimentados con 35% de proteína cruda (PC) y 18 kJ·g–1. La proteína soluble en tejido de langosta de agua dulce alimentada con 28 y 35% de PC fue superior con respecto a los acociles del grupo control. El mejor peso final promedio (9.23 g), la mejor ganancia en peso (788%) y el factor de conversión alimenticia mas bajo (1.3) se presentó en acociles alimentados con 35% de PC. Se concluye que una dieta conteniendo 35% de PC y 18 kJ·g–1 de energía es recomendada para la producción y además incrementa la respuesta inmune de los acociles en su fase de juvenil." | "This study determined the influence of dietary crude protein and energy levels on growth, survival, and antioxidant response of superoxide dismutase (SOD) in juvenile redclaw Cherax quadricarinatus. Six practical diets containing three crude protein (CP) levels (28, 35, and 40%) and two energy levels (~18 and 20 kJ·g–1) were tested. The control group was fed a commercial shrimp diet. The highest SOD activity (34.8 U·mg–1 protein) occurred in the diet with 35% CP and 18 kJ · g–1. Soluble protein in tissue of redclaw fed 28 and 35% CP increased, compared to the control. The best mean final weight (9.23 g), weight gain (788%), and the lowest feed conversion ratio (1.3) occurred with the 35% CP diet. We conclude that a dietary CP content of 35% and 18 kJ · g–1 is recommended for production and best immune responses in redclaw."