Facultad Regional Mar del Plata

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Author: search.filters.author.Mallo, Juan CarlosStart date: 2020

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    Morphological changes, peptidase activity, and effects of exogenous enzymes in the early ontogeny of Nile tilapia, Oreochromis niloticus.
    (2022-07-14) del Valle, Juana Cristina; Zanazzi, Aldo Nahuel; Rodriguez, Yamila Eliana; Haran, Nora Selma; Laitano, María Victoria; Mallo, Juan Carlos; Fernández‐Gimenez, Analía Verónica
    During the early ontogeny, the transition from endogenous (yolk protein) to exogenous feeding (artificial diets) represents a critical period linked to the undifferentiated digestive system, with low digestibility of food protein. The objectives of this work were to characterize the morphology of the early Nile tilapia (Oreochromis niloticus) developmental stages and determine the activity of alkaline and acid peptidase enzymes during the ontogenesis from hatching to 20 days post-hatching (DPH). Also, the in vitro effect that exogenous enzymes from Argentine red shrimp (Pleoticus muelleri) waste have on the alkaline peptidases of larvae from 6 to 20 DPH (which correspond to the age at which fish eat exogenous food) was studied. Both acid and alkaline peptidase activities varied throughout early ontogeny development (from 0.1 to 1, and from 0.1 to 7.1 UE mg protein−1, respectively). The patterns of both enzyme activity variation would be related with changes in endogenous, mixed and exogenous feeding. Our studies show that the additions of the enzyme extract of shrimp have a synergistic effect (from 3 to 6 times) on endogenous in vitro activity. Moreover, the zymogram analysis demonstrates that the bands corresponding to the activity of each species (tilapia and red shrimp) remain active when they are mixed. The increase in peptidase digestive capacity by addition of exogenous enzymes would maximize the assimilation of nutrients from artificial food during early development.
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    Engorde experimental de Tilapia del Nilo (Oreochromis niloticus; Linnaeus, 1758) en sistema de recirculación de agua.
    (Secretaría de Ciencia, Tecnología y Posgrado de la UTN., 2021-11-30) Zanazzi, Aldo Nahuel; Asiain, Arturo; Cecchi, Federico Alcides; Castellini, Damián L.; Mallo, Juan Carlos
    La Tilapia nilótica (Oreochromis niloticus), es un cíclido de aguas templadas y uno de los principales peces mundialmente cultivados. Los sistemas de recirculación filtran el agua, logrando una producción sustentable con el ambiente. El objetivo del presente trabajo fue realizar un ensayo experimental para el engorde de esta especie en un sistema de recirculación de agua (SRA). El trabajo fue desarrollado en las instalaciones del Laboratorio de Acuicultura (FRMDP-UTN), en donde se sembraron 472 ejemplares con un peso promedio de 176±3,2g distribuidos, en igual cantidad, en cuatro tanques de 2,5 m3 cada uno, llegando después de 155 días a un peso promedio de 542±11,3g. Se alimentó con dieta seca peletizada. Los parámetros del agua se monitorearon diariamente. La supervivencia promedio fue de 91,07%. Los resultados demostraron la factibilidad de engordar esta especie hasta un tamaño comercial dentro de este sistema.
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    Crecimiento del pez ornamental Hemichromis bimaculatus (Cichlidae) en un Sistema de Recirculación de Agua, con incorporación en el alimento de residuos industriales y algas
    (2021-08-01) Pérsico, María Marta; Cecchi, Federico Alcides; Zanazzi, Aldo Nahuel; Asiain, Arturo; Tomaselli, Brian Nahuel; Pérez, Fabiana; Prario, María Inés; Waldmann, Paula; Mallo, Juan Carlos; Patat, María Laura
    El presente trabajo tuvo como objetivo evaluar el crecimiento de juveniles del pez ornamental H. bimaculatus, Cichlidae, utilizando residuos industriales de langostino argentino y cebada cervecera, con complemento de algas en el alimento. El cultivo se realizó en un sistema de recirculación de agua a escala de laboratorio. Se evaluaron el peso y largo total de los individuos, la supervivencia, su aspecto externo y la calidad del agua del sistema de cultivo. Se hallaron diferencias significativas (p<0,05) entre las medianas de peso y largo total al compararlas con el tratamiento control, con 47,5 % de proteínas, con resultados más favorables respecto al experimental; en éste la tasa de crecimiento específico fue 2 mg/día y la sobrevivencia 98 %. Los residuos de langostino y cebada podrían ser utilizados como ingredientes en alimentos formulados para esta especie, reemplazando parcialmente a la harina de pescado, de forma más amigable con el ambiente y alta disponibilidad regional.
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    Tilapia culture in south latitudes: first report of successful fattening in hot springs of Buenos Aires province, Argentina
    (2020-08-21) Castellini, Damián Luis; Zanazzi, Aldo Nahuel; Gorosito, Angélica; Tranier, Enzo Damián; Fernández Subiela, María; Mallo, Juan Carlos
    In the present work, the feasibility of fattening Oreochromis niloticus specimens on a pilot scale in a geothermal water resource located in the Southeast of the province of Buenos Aires was analyzed. Before placing the culture units, physical and chemical characteristics of hot spring were studied to evaluate its suitability for tilapia farming. In the experimental stage, two hundred specimens with an average weight of 14.5 ± 1.8g were placed in two floating cages (1.30x1x1m) (100 individuals per cage) and they were harvested at 140 days. The specimens were fed 3 times a day with a commercial pelleted feed with a content of 35% of proteins. Monthly samplings were carried out to evaluate growth (weight and total length), survival, and water samples were collected to measure their physical-chemical characteristics. The results of the water analysis showed a high quality in the hot springs (Simplified Water Quality Index=88). The fattening results showed an average final weight of 423-435.9 g, a survival of 87-91%, SGR 1.47- 1.49%/day and the FCR was estimated at 1.05-1.07 for each cage respectively. We can conclude that this hot spring has the necessary water conditions to obtain excellent weight gains during the fattening period for the O. niloticus specimens. The present study represents the first Nile tilapia culture in the southernmost thermal waters, setting a precedent for future ventures in the area.