Lactoferrin is a multifunctional protein that has roles in iron metabolism, cell generation and differentiation, and antibacterial, antiviral, and antiparasitic activity. The
study aim was to evaluate the effect of dietary lactoferrin powder on the innate
immune response and disease resistance of silver carp (Hypophthalmichthys molitrix)
infected with Vibrio vulnificus. The study also investigates immune cells in different
organs including gills, intestine, spleen, liver, and pancreas using light, scan electron
microcopy. Two diet regimes, a basic diet and a 600-mg/kg bovine lactoferrinsupplemented diet were used. The fish were fed for 30 successive days. We included
270 apparently healthy silver carp (H. Molitrix) with an average body weight of
10 ± 2 g/fish. Addition of lactoferrin to the diet led to an increase in the activity of
non-specific immune parameters; lymphocytes, and in the monocytes percentage,
and in total protein, serum globulin, and albumin, with a corresponding increase in
phagocytic activities and indices. The histological analysis revealed increase immune
cells such as lymphocytes in intestine, rodlet cells in liver, gills, and pancreas, and the
macrophages in liver, pancreas as well as spleen. The lactoferrin-supplemented diet
significantly increased survival and disease resistance following V. vulnificus challenge, which seemed to correspond to an enhancement of non-specific immune functions in H. molitrix