Desempenho produtivo e econômica de surubins (pseudoplatystoma sp) alimentados com níveis de proteína e estocados em tanque-rede / Growth performance and economic of pseudoplatystoma sp fed with protein levels reared in net cages

O surubim (Pseudoplatystoma sp.) é uma das espécie de peixe mais apreciadas para o consumo. Por ser uma espécie carnívora, exige atenção especial no que tange às suas exigências nutricionais. Até o momento, poucos estudos foram realizados para estabelecê-las na fase de engorda, em especial em sistema de cultivo intensivo. O objetivo do presente estudo foi avaliar os desempenhos zootécnico e econômico de surubins (Pseudoplatystoma sp.) na fase final de crescimento, estocados em tanque-rede e alimentados com dietas com diferentes níveis de proteína. Os peixes, com peso de 356,6±40,3g, foram acondicionados em 12 tanques-rede de 18m3, nos quais permaneceram por cinco meses até adquirirem o peso comercial para abate. O tratamento experimental foi constituído por três dietas extrusadas comerciais, com os níveis de proteína bruta (36, 38, 40%PB) sendo substituídos gradativamente por carboidratos. Foram avaliados os parâmetros de crescimento, rendimento de filé, enzimas metabólicas e desempenho econômico. O ganho de peso, o ganho de peso diário, o consumo de dieta, a taxa de eficiência proteica, a sobrevivência e o rendimento de filé não apresentaram diferença significativa. A conversão alimentar foi melhor para os peixes alimentados com a dieta com 38 e 40%PB. Não foram observadas diferenças significativas para os parâmetros de índice hepatossomático e de enzimas hepáticas. Apesar dos maiores gastos com a ração contendo 38%PB em comparação à dieta com 36%PB, esta foi a que apresentou o melhor índice de custo por kg de peixe produzido. Os melhores índices de crescimento e o menor custo de arraçoamento foram obtidos pelos peixes alimentados com a dieta 38%PB, sendo esta, portanto recomendada para o arraçoamento na fase final de surubins em tanque-rede.

The Pseudoplatystoma sp. is one of the most appreciated fish species for consumption. Being a carnivorous species, the painted requires special attention regarding their nutritional requirements. To date, few studies have been conducted to establish them in their stage of fattening especially in intensive cultivation systems. The aim of the present study was to evaluate the growth and economic performance of Pseudoplatystoma sp fed with protein levels reared in net cages. The fish weighing from 356.6 ± 40.3g were packed in twelve net cages in 18 m3 in which they remained for five months until acquiring the commercial weight for slaughter. The experimental treatment was constituted by three commercial extruded diets with different crude protein levels (36, 38, 40% CP) gradually being replaced with carbohydrate. Growth parameters, metabolic enzymes, fillet yield and economic performance were evaluated. The gain in weight, daily weight gain, diet consumption, protein efficiency rate, survival and fillet yield did not show significant difference. The feed conversion was best for fish fed a diet with 38 and 40% CP. No significant differences were observed for the hepatossomatic index parameters and liver enzymes. There were larger expenditures on rations containing 38% PB compared to the diet with 36% CP, this presented the best index of cost per kg of fish produced. The best growth rates and lower cost of feeding were obtained by fish fed with a 38% CP diet, which is, therefore, recommended for feeding in the final phase of surubins monitored via net cages.

Atresia Folicular en Ovarios de Prochilodus lineatus / Follicular Atresia in Ovaries of Prochilodus lineatus

Durante el período reproductivo, en el ovario de los teleósteos se forman cíclicamente folículos primarios, los que maduran y son liberados en el momento de la ovulación. Sin embargo, algunos de ellos desarrollan un proceso de atresia con degeneración y reabsorción, el que para ser considerado un evento fisiológico debería predominar al final del ciclo reproductivo. Las características morfológicas de ovarios de Prochilodus lineatus fueron analizadas para identificar la presencia de folículos atrésicos como indicadores de posibles modificaciones de su biología reproductiva que afecte la repoblación de la especie. En los ovarios de P. lineatus predominaron los cambios morfológicos que se corresponden con la denominada atresia tipo I, y los folículos atrésicos fueron observados en peces con índice gonadosomático bajo que se encontraban al final del ciclo reproductivo. La atresia folicular hallada no pudo vincularse con algún proceso patológico que provoque una disminución de la especie en el ecosistema del río Paraná.

During the reproductive period, primary follicles are formed cyclically in the ovary of teleost, which mature and are released at the ovulation time. However, some of them develop a process of atresia with degeneration and resorption, which to be considered a physiological event should prevail at the end of the reproductive cycle. Morphological characteristics of ovaries of Prochilodus lineatus were analyzed for the presence of atresic follicles as indicators of possible changes in their reproductive biology affecting the repopulation of the species. In the ovaries of P. lineatus dominated the morphological changes that correspond to the so-called type I atresia, and atresic follicles were observed in fish with low gonadosomatic index who were at the end of the reproductive cycle. Detected follicular atresia could not be linked to a pathological process that causes a decline of the species in the Paraná river ecosystem.

Morfología de la Piel y Producción de Lana en Cruzamiento Absorbente con Merino Multipropósito / Skin Morphology and Wool Production on Merino Multipurpose from Absorbent Crosses

Las tendencias del mercado de fibras textiles muestran que las lanas finas son las que se adaptan a las preferencias de la industria textil. En Argentina, la producción de lanas finas es insignificante y esto representa una limitante para el crecimiento lanero del país. La necesidad de desarrollar una alternativa de producción ovina lleva a considerar al Merino Multipropósito como una opción interesante. En la provincia de Corrientes, se iniciaron cruzamientos con estos animales, pero existen inquietudes con respecto a lograr una disminución en el diámetro de la fibra y que repercuta en el peso del vellón. El objetivo del trabajo fue evaluar el efecto del cruzamiento de ovejas Corriedale con machos MPM, sobre las características de la piel y la producción y calidad de lana. Los parámetros evaluados fueron diámetro de fibra, densidad de folículos y relación S/P. Para el recuento de folículos primarios y secundarios se realizaron biopsias de piel con auxilio de un sacabocado. Las características en relación con la producción y calidad de lana se consideraron entre borregas contemporáneas. La comparación realizada en este trabajo permitiría atribuir la disminución del diámetro de fibra, al cruzamiento con MPM. La densidad de folículos en las madres Corriedale, en las borregas Corriedale y en la F1 (Corriedale x MPM) fueron diferente significativamente. La relación S/P fue 9,08 ± 2,32, 9,46 ± 1,57, y 11,93± 2,18, respectivamente. El peso del vellón en borregas de la F1 (Corriedale x MPM) fue inferior y significativamente diferente de sus contemporáneas Corriedale. El rinde al lavado en las borregas Corriedale fue superior al de las borregas nacidas del cruzamiento con MPM. Las diferencias fueron significativas en el largo de mecha entre borregas Corriedale y Corriedale x MPM. En las condiciones realizadas no se pudo comprobar todas las expectativas esperadas con el cruzamiento. Nuevas experiencias serán necesarias para respaldar morfológica y productivamente la posible inversión.

Textile market trends show that fine wools are more suitable to reach the preferences of textile industry. Production of fine wool in Argentina are insignificant, which is a limitation on the development of the country. The need to develop new alternatives of production leads us consider the Multipurpose Merinos as an option. Crossbreeding with these animals began at Corrientes state in order to achieve a reduction in the diameter of fiber and an impact on the weight of the fleece. These crossbreedings with Corriedale sheep were carried out with the objective of analyzing changes on wool production, quality and skin characteristics. Evaluation parameters were fiber diameter, density of follicles and Secondary/Primary relation. Follicle count primary and secondary were made from skin biopsies and were performed with the aid of a punch. Features regarding the production and quality of wool from sheep were considered in contemporary animals, evaluating fleece weight and clean dirty, length of strands, washing yields, coefficient variation of fiber and W / D3. The comparison made in this paper would attribute the decrease in fiber diameter to the crossing with MPM. The follicle density on Corriedale ewes, Corriedale ewe lambs in and the F1 (Corriedale x MPM) were significantly different. The S / P was 9,08 ± 2,32 ; 9.46 ± 1.57 and 11,93 ± 2,18 respectively. The fleece weight in the F1 ewe lambs (Corriedale x MPM) was lower and significantly different from its Corriedale contemporaries. The yield on wash fleece at Corriedale ewe lambs was higher than ewe lambs crossbred with MPM. The differences were significant in length of strands between Corriedale and Corriedale sheep x MPM. Expected results from the crossbreeding could not be substantiated under the conditions realized. Additional studies will be needed to support possible morphological and productive investment.