Evaluación del periodo de masculinización en la tilapia del Nilo var spring empleando 17α-metiltestosterona

Abstract

Una alternativa para reducir el uso de hormonas con aplicación inmediata en el cultivo comercial de la tilapia del Nilo, es la evaluación precisa de los tiempos de masculinización en variedades domesticadas. El objetivo del trabajo fue evaluar el porcentaje de masculinización y el crecimiento obtenido en la tilapia del Nilo alimentada con alimento comercial adicionado con 17α- metiltestosterona a diferentes tiempos. Para ello se evaluaron cinco tiempos (0, 10, 15, 20 y 25 días) de administración de hormona a una población mixta de tilapia del Nilo variedad Spring. Para cada tratamiento se utilizaron tres réplicas. Los alevines fueron sembrados a densidad de 0.5 alevines L−1 en un sistema de recirculación cerrado. El cultivo consistió de 30 días en acuarios de acrílico de 85 L y 20 días en tanques exteriores de 1000 L. La determinación del sexo se realizó con la técnica de squash. El crecimiento se determinó por medio del peso húmedo y la longitud total obtenida de las biometrías. Los resultados indican una masculinización del 100% desde los 10 días de aplicación del esteroide, pero los mayores valores de crecimiento se observaron en los grupos que recibieron el esteroide por mayor tiempo. Los resultados muestran que no es necesario administrar el esteroide durante 30 días para lograr una masculinización del 100% en variedades domesticadas y que el esteroide tiene efecto positivo en la tasa de crecimiento de los alevínes, persistiendo por algunas semanas después de terminado el tratamiento.

Effect of Fluoxymesterone on Sex Proportion and Growth Performance of Nile Tilapia (Oreochromis niloticus L.).

“…Although the duration of hormonal treatment has been pointed out as an important factor to successfully induce high rates of sex reversal, in recent years, both feminization and masculinization experiments with Nile tilapia, have shown that it is not necessary to administer the hormone for more than 20 days after the onset of the labile period to induce high rates of sex reversal [12,42,43,44]. Nakamura and coauthors [45] reports that under the light microscope, the first signs of gonadal sex differentiation appear in Nile tilapia fry at 23-26 days after hatching with the formation of the ovarian cavity in the XX gonad or the efferent duct in the XY gonad.…”

“…Tao and coauthors [38] reports that typically, when hormonal treatment is administered during the period covering 3-6 days after hatching, phenotypic sex can be successfully reversed in both sexes. In this regard, Trejo-Quezada and coauthors [44] reports starting the steroid treatment five days after hatching in Nile tilapia (Var GIFT) and obtaining a 100% males supplying 60 mg Kg -1 of 17α-Brazilian Archives of Biology and Technology. Vol.66: e23210792, 2023 www.scielo.br/babt methyltestosterone during only 10 and 15 days.…”

“…That is the reason, behind the duration used for the hormonal treatment, which was reduced by delaying the onset of steroid application, because according to the information available for Nile tilapia, after 28 days of age the gonadal differentiation has already begun, making very difficult a successful sex reversal regardless of the steroid or concentration used. The work of Trejo-Quezada and coauthors [44] was a successful part of this project, which was able to provide data that contribute to reducing the use of steroids in the process of sex reversal in Nile tilapia. However, the present work, failed to successfully move the onset of the hormonal period using a low concentration of FM.…”

Effect of the combination of fluoxymesterone and a commercial blend of additives on the sex proportion, growth, and survival of Nile tilapia (Oreochromis niloticus) fry

“…It is well known that monosex, all-male Nile tilapia (Oreochromis niloticus) populations show better growth than mixed populations, eliminating unwanted reproduction and allowing the production of homogeneous size fish (Varadaraj & Pandian 1989, Mair et al 1997, Müller-Belecke & Hörstgen-Schwark 2007 Associate Editor: Mauricio Laterça Alcántar-Vázquez et al 2014) at harvest. In recent years, the production of all-male populations has been recognized as the most effective technique to increase Nile tilapia yield under commercial farming conditions (Müller-Belecke & Hörstgen-Schwark 2007, Phumyu et al 2012, Trejo-Quezada et al 2021. Currently, the most used method to achieve monosex populations is sex reversal, through the inclusion of steroids in the balanced food supplied during the fry period (Piferrer 2001, Alcántar-Vázquez 2018 before sexual differentiation, which allows obtaining a population composed of 100% male fish (Jiménez & Arredondo 2000, Daza et al 2005, Trejo-Quezada et al 2021.…”

“…In recent years, the production of all-male populations has been recognized as the most effective technique to increase Nile tilapia yield under commercial farming conditions (Müller-Belecke & Hörstgen-Schwark 2007, Phumyu et al 2012, Trejo-Quezada et al 2021. Currently, the most used method to achieve monosex populations is sex reversal, through the inclusion of steroids in the balanced food supplied during the fry period (Piferrer 2001, Alcántar-Vázquez 2018 before sexual differentiation, which allows obtaining a population composed of 100% male fish (Jiménez & Arredondo 2000, Daza et al 2005, Trejo-Quezada et al 2021.…”