Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2007
Publication Date: May 1, 2007
Citation: Welker, T.L., Lim, C.E., Aksoy, M., Klesius, P.H. 2007. Effects of Dietary Bovine Lactoferrin on Disease Resistance, Immune Function, and Stress Resistance of Channel Catfish and Nile Tilapia. In: 31st Fish Feed and Nutrition Workshop, May 16-18, 2007, Auburn University, Auburn, AL. pgs. 27-28. Technical Abstract: Juvenile channel catfish (Ictalurus punctatus) and Nile tilapia (Oreochromis niloticus) were fed nutritionally complete, practical basal diets supplemented with bovine lactoferrin (Lf) at 0, 200, 400, 800, or 1600 mg/kg diet to apparent satiation twice daily for 5 and 8 weeks, respectively, to determine their effect on growth performance, immune function, and resistance to low-water stress and disease challenge. Generally, dietary Lf did not affect growth performance (weight gain, feed intake, feed efficiency ratio, or survival) or hematological parameters (hemoglobin, white and red blood cell counts, or hematocrit) (P > 0.05). However, feed intake was significantly lower in channel catfish fed the control diet. Crowding stress produced significant increases in plasma osmolality (only measured in tilapia), cortisol, glucose, and lactate from baseline values. Dietary Lf caused significant (P is less than or equal to 0.05) increases in plasma lactate in Nile tilapia but not channel catfish as concentrations in diet increased; however, Lf did not affect plasma glucose, osmolality, or cortisol concentrations. Levels of Lf in diet had a significant impact on survival of Nile tilapia and channel catfish following challenge with Streptococcus iniae and Edwardsiella ictaluri, respectively. Nile tilapia fed the 800 mg/kg Lf-diet had significantly higher survival than control fish, while the highest level of Lf tested (1600 mg/kg) produced the greatest survival in channel catfish. There was not a corresponding increase in activity of non-specific or specific immune parameters (plasma lysozyme, hemolytic complement, and bactericidal activities or agglutination antibody titer) with addition of Lf to diets, but plasma iron decreased and total iron binding capacity (TIBC) increased significantly in Nile tilapia with increasing dietary concentrations of Lf. A similar, non-significant trend was observed for plasma iron in channel catfish. The ability of Lf to sequester iron, an essential nutrient required for the growth of bacteria, is regarded as one of its key antibacterial properties. The increased resistance to disease seemed to correspond with a decrease in plasma iron concentrations and not enhancement of non-specific or specific immune functions.