The Impact of Interaction of Photoperiods and Vitamins Supplementation on the Hematological Parameters, Reproductive Hormones, Liver Function, and Reproductive Performance of the Female Nile Tilapia (Oreochromis niloticus)

Three vitamin supplementations [non-supplemented, vitamin A (V.A), and vitamin D (V.D)] and three different photoperiods (8 light/ 16 dark, 12 light/ 12 dark, and 24 light/ 0 dark) were tested to evaluate their impacts on the hematological parameters, reproductive hormones, liver activity, and reproductive performance of the female Nile tilapia. Approximately, 810 females with an average-weight of 272.56± 37.5g were stocked inside 27 concrete tanks (3m³), with 30 fish/ tank. Fishwere fed with a commercial diet (31.2% protein) at a daily rate of 3% for 60 days. The results revealed that the significant values of hematological parameters were observed under 8L/ 16D, while V.D could increase the mean cell volume, mean cell hemoglobin, and leucocytic count. The interaction effects of photoperiods and vitamins have a significant effect on the hematological parameters.  Reproductive hormones were  significantly increased under 8L/ 16D, while significant differences were observed by V.D followed by V.A. The interaction between 8L/ 16D and V.D enhanced the reproductive hormones. Transaminases activities were increased significantly under 8L/ 16D. For the interaction effects, the highest transaminases activities were observed under 8L/ 16D without any vitamin addition. The highest gonado and hepato somatic indexes and oocyte diameter were observed under 12L/ 12D, while the highest fecundity was recorded under 24L/ 0D. V.A could improve the gonadosomatic index and oocyte diameter, while the highest fecundity was observed with V.D. The interaction of photoperiods and vitamins A and D supplementation could improve the reproduction performance significantly. In conclusion, the interaction between photoperiod and vitamin A and D supplementation could positively affect the fish performance, hematological parameters, reproductive hormones, liver function, and reproductive performance of the Nile tilapia broodstock.