Interaction of low-level dietary supplementation of Chlorella vulgaris Beijerinck, 1890, and feeding duration on growth hormone, growth performance and serum biochemistry of red hybrid tilapia (Oreochromis mossambicus × Oreochromis niloticus)

Chlorella is one of the most widely accepted Chlorophyta used by many as livestock and aquaculture feed. Nonetheless, 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 (GH), growth performances, serum-biochemical indices, hepatic function and some immunological parameters of red hybrid tilapia. The fingerlings (mean weight: 14.25 ± 0.01 g, length: 13.5 ± 0.49 cm) were fed diets containing 0, 0.99%, 2.91% and 4.76% of C. vulgaris powder per kilogram dry diet for 90 days. GH, growth performance, serum-biochemical indices (total serum protein, albumin, globulin, glucose, aspartate aminotransferase and alanine aminotransferase) and some immunological (respiratory burst and lysozyme activities) parameters of the fish were examined after 30, 60 and 90 days of feeding. The results demonstrated that tilapia fed C. vulgaris-supplemented diets showed increased levels of respiratory burst, lysozyme, albumin and total protein, GH and growth performances (P