Influence of Dietary Lipid and Temperature on Bactericidal Activity of Channel Catfish Macrophages

Abstract

We fed juvenile channel catfish Ictalurus punctatus purified diets containing different lipid sources for 90-110 d to examine the influence of dietary lipids on intracellular killing of Edwardsiella ictaluri by pronephros macrophages. The diets contained either menhaden oil, soybean oil, beef tallow, or a combination of all three lipids. We performed the study with nonimmune and immunized fish acclimated to optimal (28°C) and suboptimal (19°C) temperatures. In both temperature trials, bactericidal activity was positively correlated with the level of n-3 fatty acids in the diet (particularly long-chain highly unsaturated fatty acids). Vaccination resulted in substantially enhanced bactericidal activity, except at suboptimal temperature in fish fed the diet containing beef tallow (primarily saturated and monoenoic fatty acids). Overall results were similar at optimal and suboptimal temperatures. This study demonstrates the potential for nutritional manipulation of disease resistance in fish and illustrates the need for standardized diets in fish health research.

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…In channel catfish these include increased phagocytic activity ( Sheldon and Blazer 1991;Lingenfelser et al 1995), which, as suggested in mammals (de Pablo and de Cienfuegos 2000), is related to increased membrane fluidity. Lower haematocrit, higher thrombocyte counts, and increased resistance to erythrocyte fragility has been noted (Klinger et al 1996).…”

Determination of Hematological Status as Health Indicator of European Sea Bass (Dicentrarchus labrax L.) Fed Different Dietary Fatty Acids

“…In similar studies conducted on different marine species, peripheral blood leukocytes and functions were affected by the fatty acid profile of the diet. (Sheldon and Blazer, 1991;Montero et al, 2003;Mourente et al, 2007). Mourente et al (2007) mentions the study of plant oils are used as an alternative to fish oil, important changes have been determined from the non-specific immune system.…”

“…Fatty acids are quite important for fish growth, development, cell membrane functions, synthesis of vitamins and hormones, and many other basic functions (Fracalossi and Lovell, 1994;Sheldon and Blazer, 1991). The essential fatty acid balance in the diet is also found to be important for immune system development of fish and other aquatic organisms and for resistance against disease and various stress factors (Montero et al, 2003).…”

A dietary dairy/yeast prebiotic and flaxseed oil enhance growth, hematological and immunological parameters in channel catfish at a suboptimal temperature (15°C)

“…Channel catfish-fed diets rich in n-3 fatty acids had increased immune function at low temperatures, but at high temperatures a diet rich in n-6 fatty acids enhanced disease resistance (Lingenfelser et al, 1995). Sheldon and Blazer (1991) also positively correlated dietary n-3 concentration (particularly long-chain polyunsaturated fatty acids, or LC-PUFA), with enhanced intracellular pronephros macrophage killing of Edwardsiella ictaluri in channel catfish at optimum (28°C) and suboptimal (19°C) temperatures for growth. Lysozyme activity was higher in channel catfish maintained at 22°C and fed diets high in n-3 fatty acids (with fish or flax oil) than those fed a diet with soybean oil (Suja et al, 2012).…”