Jatropha curcaskernel meal as a replacement for fishmeal in practical Nile tilapia,Oreochromis niloticusfeeds
Jatropha curcas is an upcoming oil-seed plant with increasing cultivation area each year throughout the tropics. After de-oiling the seeds, a protein-rich meal (JKM) is left behind, which has a similar amino acid composition and content compared to fishmeal. To test JKM as an alternative protein source, a mixed diet was formulated in which 25% of the total dietary protein was derived from fishmeal and the rest from soybean meal, rice bran and wheat meal (control). Three further isonitrogenous and isoenergetic diets replacing 30%, 70% or 100%, respectively, of the fishmeal protein with JKM were produced and fed to juvenile Nile tilapia (Oreochromis niloticus) for 8 weeks. There were no significant differences in growth parameters between all treatments containing JKM, however, regression analysis revealed a significant negative correlation of JKM content to final weight and specific growth rate. The 70% and 100% replacement levels showed higher body lipid and significantly lower ash content. JKM is a promising alternative protein source in aquaculture diets for tilapia, though slower growth in this experiment suggests the need for further research to improve the nutritional value of JKM.