Juan José Santinón

Fontes não-convencionais de proteína na primeira alimentação do bagre sul americano (Rhamdia quelen)

O presente estudo teve como objetivo avaliar diferentes fontes de proteina na primeira alimentacao de jundia (Rhamdia quelen) sob condicoes de laboratorio. Foram testadas tres racoes balanceadas secas: ovo de peixe (TA), hidrolisado de carcaca do peixe (TB) e figado de frango cru (TC), na quais foram analisadas, pelo crescimento, a biomassa final produzida e a sobrevivencia das larvas. O ensaio teve uma duracao de 20 dias, e as racoes foram fornecidas ad libitum. As larvas alimentadas com ovo de peixe apresentaram os melhores resultados com peso medio individual de 340mg, sobrevivencia de 57% e biomassa final de 1.350mg, diferindo significativamente dos demais tratamentos. Os resultados indicaram que a formulacao de racoes balanceadas com ovos de peixes fornecida na primeira alimentacao de larvas de jundia pode tornar-se uma alternativa promissora na larvicultura dessa especie.

Desarrollo Ontogénico de la Columna Vertebral y del Esqueleto Caudal en Larvas de Rhamdia quelen en Condiciones de Larvicultura Intensiva

Se analiza por primera vez el desarrollo osteologico de la columna vertebral y del esqueleto caudal en larvas de Rhamdia quelen mantenidas bajo condiciones controladas y con alimentacion artificial. Entre los dias 1 a 20 posteriores a la eclosion (dpe) se muestrearon a intervalos regulares 400 larvas, que se colorearon y transparentaron siguiendo la tecnica de Taylor & Van Dike. En los primeros dias de vida, las larvas presentan una notocorda recta en toda su longitud. El inicio de la formacion de la columna vertebral fue observado a los 7 dpe con la aparicion de las espinas neurales y hemales, y entre los 9 y 10 dpe para las tres primeras vertebras. La osificacion de la columna vertebral ocurrio en sentido craneo-caudal y fue completa a los 20 dpe. El esqueleto caudal inicia su desarrollo entre los 3 y 4 dpe, con la formacion de los hipurales (H), parahipural (PH) y los radios caudales. Los H 1 al 4 se formaron como primordios cartilaginosos en la cara ventral de la porcion distal de la notocorda, mientras que posteriormente lo hicieron el H 5 y el PH en el extremo distal y proximal del esqueleto caudal, respectivamente. El complejo centro ural (CCU) se osifico inicialmente en dos partes, una anterior que resulta de la combinacion del centro preural 1 y el ural 1 y una posterior con el ural 2. Los primeros radios de la aleta caudal aparecieron en larvas en flexion, mientras que despues de los 13 dpe, todos los ejemplares presentaron los radios principales osificados (ocho en la parte superior y ocho en la inferior). El desarrollo de la columna vertebral y del esqueleto caudal en R. quelen muestra patrones similares a los descriptos en otros peces teleosteos aunque con algunas particularidades que lo diferencian de los grupos relacionados.

Dietary soybean meal on growth and intestinal morphology of South American catfish, Rhamdia quelen, larvae

The effects of the replacement of bread yeast by soybean meal in diets for Rhamdia quelen larvae on growth, survival, and intestinal morphology were analysed. Larvae were fed for 20 days with five diets: a control diet formulated with 57% of bread yeast, and other four diets in which soybean meal at concentrations of 14.25, 28.5, 42.75 and 57% was added to obtain 25, 50, 75 and 100% of bread yeast replacement. Growth and survival parameters were negatively affected by dietary soybean meal inclusion. Larvae fed control diet showed significantly higher mean weight, specific growth rate, final biomass, and survival rate than larvae from other treatments. Enterocyte height and fold width of the posterior intestine showed highest values in the control group, and an inverse linear relationship with the level of dietary soybean meal inclusion was observed, however, in the anterior intestine the morphology parameters were not affected by the diet. These results indicate that inclusion of soybean meal in diets for R. quelen larvae negatively affects growth and survival, as well as the capacity for digestion and absorption of nutrients, mainly in the posterior intestine.

Development of the Vertebral Column and Caudal Skeleton in Prochilodus lineatus Larvae under Laboratory Conditions

Se describe el desarrollo osteologico de la columna vertebral y del esqueleto caudal en larvas de sabalo (Prochilodus lineatus) bajo condiciones controladas hasta los 30 dias posteriores a la eclosion (dpe). El inicio de la formacion de la columna vertebral fue observado entre los 10-12 dpe (8,3 mm de longitud estandar, LE) con la aparicion de los primeros procesos neurales, hemales y cuerpos vertebrales pre-caudales. La osificacion de la columna vertebral ocurrio en sentido craneo-caudal y fue completa a los 28 dpe (22,6 mm LE). El esqueleto caudal inicio su desarrollo entre los 6 y 8 dpe con la formacion de los hipurales (H), parahipural (PH) y los radios caudales principales y secundarios. Los H 1 al 3 se formaron como primordios cartilaginosos en la cara ventral de la porcion distal de la notocorda, mientras que posteriormente se formaron los H 4 al 6 y el PH. Los primeros radios de la aleta caudal fueron observados en correspondencia con la formacion de los H 2 y 3, mientras que a los 28 dpe se observo la completa formacion de los mismos, existiendo 10 radios en el lobulo dorsal y 9 en el lobulo ventral. Los epurales, en numero de tres, fueron evidentes como elementos cartilaginosos en dorsal de la notocorda y distalmente a los arcos neurales, permaneciendo sin osificarse hasta los 25 dpe. El complejo centro ural se constituyo por la fusion de tres estructuras, el centro preural 1, el ural 1 y 2. El desarrollo de la columna vertebral y del esqueleto caudal muestran patrones similares a los descriptos en otros teleosteos.

Duração da larvicultura sobre o desempenho posterior de juvenis de jundiá, Rhamdia quelen, recriados em tanques-rede

A 3x2 factorial trial with three replicates (n=18) was carried out aiming to evaluate Rhamdia quelen fingerling growth and survival rates, stocked in cages, in external ponds until attain 65 days of life. Fish used come from an intensive hatchery system, where were fed in laboratory with three different diets until attain 10 and 15 days old, before being transferred to cages. Once in cages, fishes were fed until satiation with commercial balanced diet containing 28% crude protein. At the end of the experience, there were no significant differences between treatments for any of the estimated parameters (P> 0.05). Similarly, the values of growth and survival obtained were similar between the groups of fish transferred with 10 and 15 days old. The results show that transference of 10 days old catfish larvae to the cages would be the more appropriate management, reducing feeding and operating costs that involves the larviculture under controlled laboratory conditions.

Isolation and Selection of Potentially Beneficial Autochthonous Bacteria for Piaractus mesopotamicus Aquaculture Activities

Piaractus mesopotamicus is the most produced specie in Argentinian fish culture with an annual production of 2,017 tons. The high demands of specimens generated a deficit of larvae, juveniles and sexually mature adults. The high stress conditions and the incidence of diseases had intensified this deficit. Probiotics are proven to increase survival and growth rates in aquaculture. The first step in the design of a putative probiotic is the selection of adequate microorganisms to boost fish health. Lactic Acid Bacteria and Bacillus are generally accepted as probiotics in aquaculture. In this work we obtained 522 isolates from different anatomical parts of P. mesopotamicus, with a total of 30 lactic acid bacteria (LAB) and 8 Bacillus strains submitted for the evaluation of their beneficial properties. Only eight of these strains were selected for further “in vivo” assays based on following criteria: production of inhibitory metabolites and biosurfactants, screening of antagonistic activity against foodborne and pathogenic microorganisms, ability to emulsify polar solvents and compatibility between strains. All selected microorganisms were identified by sequencing 16S RNA gene. Pure cultures of all strains herein studied are preserved in Centro de Referencia de Lactobacilos (CERELA-CONICET) and Laboratorio de Sanidad Animal of the Estacion Experimental Agropecuaria Rafaela, Instituto Nacional de Tecnologia Agropecuaria (INTA) culture collections.