Effects of feeding regime on food intake and growth of nile tilapia（ Oreochromis niloticus）

In order to investigate the effects of feeding regime on growth and food intake of genetic improvement of farmed tilapia（ GITF tilapia），an 8-week experiment was conducted to determine the optimal feeding level and feeding frequency for the aquaculture of tilapia. The study investigated the effects of different feeding levels（ 100%， 90%，80%，70%，60%，50% of satiation diet） and feeding frequencies（ once，twice，thrice，four times a day） on food intake，growth performance，biochemical composition of white muscle and mRNA expression level of CCK1， NPY，and Orexin in tilapia. Results showed that higher or lower feeding level always enhanced feed coefficient（ FCE） and mRNA expression level of NPY in hypothalamus. On the contrary，specific growth rate（ SGR），feed conversion ratio（ FCR） and mRNA expression level of CCK1 showed signs of decrease. Only crud fat content displayed a positive response to ration level. Moreover，feeding frequency showed no significant effects on all indices. Higher or lower feeding frequency led to lower FCR and SGR. Increased feeding frequency negatively affected crud protein and lipid deposition in skeletal muscle. The mRNA expression level of CCK1 was lower by higher feeding frequency，while the mRNA expression level of Orexin was reversed. In summary，80% of satiation diet as optimal feeding level and feeding tilapia twice a day was proposed.