Proceedings of the Third World Fisheries Congress: Feeding the World with Fish in the Next Millenium—The Balance between Production and Environment
Effects of Bambermycin and Virginiamycin on Performance and Body Composition of Juvenile Channel Catfish Ictalurus punctatus
Chhorn Lim, Phillip H. Klesius, Ronald Phelps
In addition to nutrients, feeds and feed ingredients contain compounds that may positively or negatively affect animal metabolism. These compounds may occur naturally in feedstuffs or be added to meet physiological needs, improve or preserve the quality of the diet, or fulfill economic purposes. These substances include hormones, antibiotics, pellet binders, immune modulators, antioxidants, and feed attractants (NRC 1993).
Numerous studies have demonstrated that subtherapeutic concentrations of antibiotics improve the growth and feed efficiency of poultry (Harms et al. 1986) and of swine (Vervaeke et al. 1979). It has been suggested that the growth-promoting action of antibiotics may be due to:
• an inhibitory effect on noxious bacteria;
• an increase in the absorption rate of nutrients due to thinning of intestinal wall; and
• the sparing effect on the dietary requirement for B-complex vitamins (Eyssen et al. 1962).
March and Biely (1967) indicated that the vitamin-sparing effect of antibiotics appears to be related to an increase in the absorptive capacity of the intestine.
Antibiotics bambermycin and virginiamycin have been used in poultry diets to improve growth and feed efficiency (Combs and Bossard 1963; George et al. 1982; Harms et al. 1986; Henry et al. 1987; Izat et al. 1989). However, information on the potential growth-enhancing effects of these antibiotics in fish is limited. Ahmad and Matty (1989) observed improved growth of juvenile common carp Cyprinus carpio fed diets containing virginiamycin at concentrations of 40, 80, or 100 mg/kg. Similarly, growth, feed use efficiency, and protein and energy retention of common carp fed diets containing 40 mg virginiamycin/kg improved 17–40% in cage-grown fish (Viola and Arieli 1987) and 10% in pond-grown fish (Viola et al. 1990). Tilapia, however, did not respond to the dietary addition of virginiamycin (Viola and Arieli 1987).
No study has assessed the performance of channel catfish Ictalurus punctatus fed diets supplemented with bambermycin and virginiamycin. Thus, this study was conducted to determine the effects of various dietary levels of bambermycin or virginiamycin on growth, survival, feed intake and efficiency, protein and fat gain, and whole body composition of juvenile channel catfish.
A commercial diet containing approximately 40% crude protein and 10% fat was used as the basal diet. The diet was ground to pass through a 0.75- mm screen. The basal diet was supplemented with 0 (control), 1, 2, 4, and 8 mg of bambermycin (flavomycin)/kg of diet or 3, 6, 12, and 24 mg of virginiamycin (staphylomycin)/kg of diet. Celufil was used as a filler to make up the differences between the weights of antibiotics. Carboxymethylcellulose (3% level) was added as a binder. All diets were pelletized again through a 2.38-mm-diameter die in a Hobart meat grinder and dried at room temperature to a moisture content of about 10%. Pellets were broken into small pieces and stored at – 18°C until used.