Effect of Spirulina platensis and Azolla nilotica as feed additives on growth performance, antioxidant enzymes and fecundity of Oreochromis niloticus

This study was conducted in two experiments. Experiment 1 aimed to investigate the growth promoting and antioxidative effects of Azolla nilotica (AZN) and Spirulina platensis (SP) in Oreochromis niloticus. Seven fish groups (G1G7), each in three replicates, were fed a basal diet (control), AZN 5%, AZN 10%, SP 0.5%, SP 1%, a mixture of Azolla nilotica 5% and Spirulina platensis 1% (AZN 5 %SP 1% mix), and a mixture of Azolla nilotica 10% and Spirulina platensis 1% (AZN 10% SP 1% mix), respectively, for 3 months. The results showed a significant increase in growth indices (weight gain, specific growth rate, average length gain, feed efficiency ratio), and a decrease in the feed conversion ratio in all supplemented groups compared to control. Hepatosomatic index in G4 and G5 groups, and intestinalsomatic index in G4 G6, and in G5 and G6 were obviously higher than control. Splenosomatic index and antioxidant enzymes (GSHpx, SOD and CAT) markedly increased in G5 and G6 compared to control. Significant increase (p 0.05) in white blood cells was recorded in G2 and G4. Experiment 2 verified the effect of one month supplementation of SP 1% on males and females O. niloticus fecundity. Males fed with SP 1% had an enhanced fertility as indicated by an increase in sperm density, spermatozoa motility and livability rates compared with the control. There was a significant increase in eggs number and the fecundity index in unripe females and a tendency of egg size to increase in ripen fish. It could be concluded that SP 1% and AZN 5% supplementation is advantageous to improve O. niloticus growth and fecundity.