Effect of replacing different levels of dietary fishmeal with Jatropha curcas kernel meal on the development of Nile tilapia Oreochromis niloticus (Linnaeus, 1758)

Abstract

The present trial tested the applicability of Jatropha curcas kernel meal (JKM) as a protein source in diets for Nile tilapia (Oreochromis niloticus) in terms of growth and body composition. Four diets were produced replacing 0% (Control), 50% (J50), 75% (J75) and 100% (J100) of fishmeal with JKM. In a fifth diet, 70% of fishmeal was replaced by JKM, and another 20% replaced by blood meal to minimize crystalline lysine addition. Body mass gain of fish fed the control diet was significantly higher than in all other treatments. However, specific growth rate (SGR) and feed conversion ratio (FCR) were not significantly different between diets J50, J75 and the control. Fish fed the control diet had a lower body protein content, but higher body fat and energy content than fish fed the JKM-based diets. An adaptation of fish fed diets J50, J75 and J100 could also be observed, as these diets showed worse FCR-values over most of the first three quarters of the experiment and equal (or in the case of J75, even significantly better) FCR-values over the final 2 weeks. Despite slightly slower growth, JKM should be further included in the search of alternative plant-feedstuffs in diets for tilapia, as the growth observed here for up to 75% replacement of fishmeal was very promising.