Utilization of cottonseed meal supplemented with iron for detoxification of gossypol in Nile tilapia, broodstock and their impact on the hatchability of their progenies

Abstract

Nile tilapia broodstock fish of an initial average weight 72.3 g were stocked in 15 glass aquariums (500 L each) at 12 fish per aquarium were fed on cottonseed meal (40% CSM) diets as a total replacement of fishmeal. The diets were supplemented with different levels of iron (67, 67, 290, 580 and 870 mg/kg diet-1) and supplemented with methionine and lysine to be similar to control diet. The fish fed twice daily at a rate of 2% of the total fish biomass daily until the end of the experiment. The results showed that final fish weight, specific growth rate and number of larvae produced increased with increasing iron level and reached maximum when fish fed diet contained 40% CSM supplemented with 580 mg Fe kg diet-1 without causing, significant reduction in growth performance. In addition, the best results of larvae obtained from broad stock fed on diet contained 40% CSM supplemented with 580 mg Fe kg diet-1. Red blood cell count, hematocrit and hemoglobin were increased with increasing levels of iron and significantly affected by dietary iron. Apparent digestibility coefficients of protein, fat dry matter and energy were relatively high for most diets supplemented with iron and increased by increasing iron supplementation. There were no significant (P>0.05) differences among fish fed diets 1 (100% FM) 4 and 5 which contained 100% CSM with additional 580 and 870 mg Fe kg diet supplemental iron. This study recommended that broodstock fed on diet contained 40% CSM supplemented with 580 mg Fe kg diet-1 was comparable to fishmeal basal diet and have higher economic evaluation. © 2012 Gaber MM, et al.