LAUSR

Chlorella is one of the most widely accepted Chlorophyta used by many as livestock and aquaculture feed. However, different studies on the overall performances of fish reported the unfavourable effect of high-level supplementations of Chlorella vulgaris. The current study determined the impact of low-level dietary supplementation of C. vulgaris alongside the different feeding durations and their interactions on the growth hormone, growth performances, serum-biochemical indices, hepatic function, and some immunological parameters of red hybrid tilapia. The fingerlings (mean weight and length 14.25 ± 0.01 g, 13.5 ± 0.49 cm, respectively) were fed diets containing 0, 0.99%, 2.91%, and 4.76% of C. vulgaris powder kg-1 dry diet for 90 days. Growth hormone, growth performance, serum-biochemical indices (total serum protein, albumin, globulin, glucose, aspartate aminotransferase, alanine aminotransferase), and some immunological (respiratory burst, lysozyme activities) parameters of the fish were examined after 30, 60 and 90 days of feeding, respectively. The results demonstrated that tilapia fed C. vulgaris supplemented diets showed increased levels of respiratory burst, lysozyme, albumin and total protein, growth hormone, and growth performances (p<0.05), and the effects were duration dependent. Following the 90 days of feeding, there was no adverse effect on the hepatic function of the fish. Besides, low survivability was observed in the control group than in the group fed the experimental diets. The group fed the diet supplemented with 4.76% C. vulgaris had significantly higher (p < 0.05) lysozyme activity throughout the duration of the feeding experiment. These results indicate that C. vulgaris enhanced growth performances, growth hormone concentration, serum-biochemistry, and some immunological parameters of red hybrid tilapia.