β-Carotene of Arthrospira platensis versus vitamin C and vitamin E as a feed supplement: Effects on growth, haemato-biochemical, immune-oxidative stress and related gene expression of Nile tilapia fingerlings

Microalgae are one of the most important sources of natural bioactive compounds, especially those revealing antioxidant activity such as beta-carotene. Thus, this study was to compare the effects of dietary Vitamin C (L-ascorbic acid) or Vitamin E (alpha-tocopherol) with beta-carotene extracted from Arthrospira platensis on Nile tilapia (Oreochromis niloticus) on growth, feed utilization, blood indices, antioxidant activity, non-specific immunological indices and related gene expression. Three hundred and sixty apparent healthy Nile tilapia (5.80 +/- 0.286g) were randomly distributed into four groups. Four isonitrogenous and isoenergetic diets were performed. A control diet was compared against three experimental diets supplemented with Vitamin C (0.5 mg kg(-1) diet), Vitamin E (1 g kg(-1) diet) or beta-carotene (0.5 g kg(-1) diet) for 10 weeks. According to the results, there was no significant difference in feed intake (p>0.05) between experimental diets. Dietary Vitamins C and E and beta-carotene significantly (p < 0.05) enhanced the weight gain, final body weight, protein efficiency ratio, specific growth rate and apparent protein utilization in all groups, whereas the best FCR (p = 0.017) and the highest weight gain (p = 0.007) were detected in the beta-carotene diet. Fish survival rates differed significantly (p < 0.05) amongst treatments, whilst fish fed a diet supplemented with beta-carotene recorded the highest survival rate. The supplemental diet with beta-carotene boosted the values of the biochemical and haematological parameters (p <0.05) compared with the control diet. The activities of catalase, superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in the liver (p = 0.0560; p = 0.0032; p = 0.0353 respectively) and tilapia muscles were higher in fish fed either beta-carotene or Vitamin E (p = 0.0579; p = 0.1494; p = 0.2145 respectively) than other groups. The highest values of SOD, CAT and immune globulin M-2 gene expression (p <0.05) were found in fish fed a diet enriched with beta-carotene. These results suggested that the dietary incorporation of beta-carotene had a superior impact on growth performance, haemato-biochemical and immune-oxidative stress biomarkers in addition to the associated gene expression of Oreochromis niloticus.

Automated summary

This study compared the effects of dietary Vitamin C, Vitamin E, and beta-carotene extracted from Arthrospira platensis on Nile tilapia. The results showed that the addition of beta-carotene in the diet had a superior impact on the growth, immune indices, and antioxidant activity of the Nile tilapia.