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Abstract
We evaluated the hypothesis that administering dietary Aloe vera to sexually undifferentiated fry of genetically improved farmed Nile Tilapia Oreochromis niloticus for 30 d would affect their sex ratio. Five experimental treatments were designed, including a control and 100% A. vera powder incorporated into the feed at 0.5, 1.0, 2.0, and 4.0%. After 30 d of feeding, the experimental diets were replaced with a commercial diet, which was administered to the fish for another 42 d to attain the size at which sex determination was possible. Based on logistic regression analysis, an increase in the A. vera inclusion level from 1.0% to 4.0% resulted in a significantly greater percentage of males compared to the control and the 0.5% A. vera inclusion level, with the 4.0% A. vera group presenting potent masculinization effects (67.62% male). However, the survival percentage among fish that received 4.0% A. vera was significantly lower than survival in the other groups. The present results indicate that A. vera extracts have the potential to be used as sex-reversal agents in Nile Tilapia culture, but additional studies are necessary.
Received December 30, 2015; accepted September 4, 2016 Published online December 6, 2016
ACKNOWLEDGMENTS
We are grateful for the financial support provided by the following grants, which made this work possible: the Special Fund for Agro-Scientific Research in the Public Interest (2015JBFR04) and the National Science and Technology Program (2012BAD26B03-1). We also thank the Wuxi Fisheries College, Department of Biotechnology, Nanjing Agricultural University, China, for providing facilities for the research. Furthermore, we thank Mehmet Sinan Lyisoy (Necmettin Erbakan University, Turkey) and Rebekka N. Shikesho (Namibia Field Epidemiology and Laboratory Training Program) for assistance in statistical analyses. The anonymous reviewers are greatly appreciated for their constructive criticism and inputs.