Enhancement of The Nonspecific Defense Activity of The Skin Mucus of Red Sea Bream by Oral Administration of Bovine Lactoferrin

Abstract

Bovine lactoferrin was evaluated for its ability to enhance the nonspecific defense activity of the skin mucus of red sea bream, Pagrus major. Oral administration of lactoferrin (4 to 400 mg/kg body weight/day) to the fish resulted in increased mucus production, and increased amounts of lactoferrin and a lectin in the skin, though no significant change in lysozyme activity in the mucus was observed. In lactoferrin-treated fish, the number of granulocytes and lymphocytes in the blood were also significantly increased. These results suggest that lactoferrin may enhance the biodefense ability of red sea bream through (i) promoting the secretion of mucus on the body epidermis and (ii) promoting an increase in nonspecific defensive factors secreted in the mucus, and (iii) promoting an increase in the number of granulocytes and lymphocytes in the blood. In the group administered lactoferrin at 400mg/kg B.W./day, however, the growth was inhibited slightly and the amount of mucus secreted on the skin decreased after 42 days.