The present study aimed to assess the possible effects of Assam tea (Camellia sinensis) extract (ATE) on growth performances, immune responses, and disease resistance of Nile tilapia, Oreochromis niloticus against Streptococcus agalactiae. Five levels of ATE were supplemented into the based diet at 0, 1, 2, 4, and 8 g kg-1 feed of Nile tilapia fingerlings (10.9 ± 0.04 g initial weight) in triplicate. After four and eight weeks of feeding, fish were sampled to determine the effects of the tea supplements upon their growth performance, as well as serum and mucosal immune responses. A disease challenge using S. agalactiae was conducted at the end of the feeding trial. Fish fed ATE revealed significantly improved serum lysozyme, peroxidase, alternative complement (ACH50), phagocytosis, and respiratory burst activities compared to the basal control fed fish (P<0.05). The mucus lysozyme and peroxidase activities were ameliorated through ATE supplementation in the tilapia diets. Supplementation of ATE significantly (P<0.05) enhanced final body weight, weight gain, and specific growth rate; while a decreased feed conversion ratio was revealed at 2 g kg-1 inclusion level, after four and eight weeks. Challenge test showed that the relative percent survival

No abstract

No abstract

The optimal concentration of a panel of individual and combined carotenoid sources on skin pigmentation in fancy carp was investigated by nine experimental diets that were formulated and supplemented with astaxanthin at 25 mg kg−1, lutein at 25 and 50 mg kg−1, β‐carotene at 25, 50 and 75 mg kg−1, and lutein combined with β‐carotene at 25 : 25 and 50 : 50 mg kg−1, while a diet without supplemented carotenoid served as a control. The results showed that serum TC of fish fed diets containing supplemented with lutein plus β‐carotene at 25 : 25; 50 : 50 mg kg−1 and lutein 50 mg kg−1 diet were higher than the other treatments (P ≤ 0.05). Serum TC of the respective treatments was 6.2 ± 2.0, 7.8 ± 3.3 and 7.3 ± 1.9 μg mL−1 serum, respectively. Fish fed diets combined with lutein and β‐carotene at 25 : 25, 50 : 50 mg kg−1 and lutein 50 mg kg−1 diet had serum astaxanthin concentrations similar to fish fed the diet with astaxanthin alone at 25 mg kg−1. Serum astaxanthin concentrations was 0.7 ± 0.01, 0.9 ± 0.01, 0.4 ± 0.02 and 1.7 ± 0.18 μg mL−1 serum, respectively. The chromaticity of fish body skin of red and white position was assessed by colourimetry using the CIE L*a*b (CIELAB) system. Pigmentation response of skin redness of fancy carp fed with diets combined with lutein and β‐carotene at 25 : 25, 50 : 50 mg kg−1 and lutein 50 mg kg−1 were higher than other treatments (P ≤ 0.05) but they were similar to fish fed with 25 mg kg−1 astaxanthin diet. The redness (a* values) of fish fed diets with diets combined with lutein and β‐carotene at 25 : 25, 50 : 50 mg kg−1 and lutein 50 mg kg−1 were 28.3 ± 0.53, 29.9 ± 1.38, 28.8 ± 3.95 and 28.5 ± 2.49, respectively. After 3 weeks of feeding the experimental diets, the fish fed on a diet without carotenoid supplement for one week demonstrated that the same three groups still retained their redness and had an overall tendency to improve skin colouring. Finally, concentrations 50 mg kg−1 of lutein, or the combination of lutein and β‐carotene at 25 : 25 mg kg−1 showed the highest efficiency for improving skin pigmentation and redness of skin.

No abstract