Effects of Assam tea extract on growth, skin mucus, serum immunity and disease resistance of Nile tilapia (Oreochromis niloticus) against Streptococcus agalactiae.
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 (RSP) of fish in each treatment was 33.33%, 60.00%, 83.33%, 76.68%, and 66.68% in groups fed 0, 1, 2, 4, and 8 g kg-1, respectively. In summary, diets supplemented with ATE especially at 2 g kg-1 increased the humoral and mucosal immunity, enhanced growth performance, and offered higher resistance against S. agalactiae infection in Nile tilapia.
['Van Doan|Hien|H|', 'Hoseinifar|Seyed Hossein|SH|', 'Sringarm|Korawan|K|', 'Jaturasitha|Sanchai|S|', 'Yuangsoi|Bundit|B|', 'Dawood|Mahmoud A O|MAO|', 'Esteban|Maria Ángeles|MÁ|', 'Ringø|Einar|E|', 'Faggio|Caterina|C|']
D000821:Animal Feed D000818:Animals D028241:Camellia sinensis D023681:Cichlids D004032:Diet D019587:Dietary Supplements D060467:Disease Resistance D004305:Dose-Response Relationship, Drug D005393:Fish Diseases D010936:Plant Extracts D018515:Plant Leaves D013290:Streptococcal Infections D013292:Streptococcus agalactiae
Assam tea extract Disease resistance Nile tilapia Growth performance Mucosal immunity S. agalactiae Humoral immunity