EFFECT OF DIETARY LINOLEIC ACID LEVEL ON GROWTH, FOOD CONVERSION AND SURVIVAL OF CHANNEL CATFISH

Semipurified diets containing 2.0 to 2.5% highly purified linoleic acid as the only dietary lipid produced similar growth responses in channel catfish fingerlings fed experimental diets for 14 weeks. Poorest growth was demonstrated by fish on a fat-free diet and a diet which contained 4.0% linoleic acid, but growth on those diets was not significantly different (p > 0.05) from that obtained on diets containing 3.0 or 3.5% linoleic acid. Best food conversion (1.9 g of feed offered/g of weight gain) was associated with the diet containing 2.5% linoleic acid and poorest (2.6) occurred in fish which received 4.0% linoleic acid. Survival was highest (100%) in fish fed 2.0% linoleic acid and decreased linearly with increasing dietary linoleic acid level. The results of this study support the theory that poor growth of channel catfish on diets high in vegetable oils cannot be solely attributed to high levels of dietary linoleic acid.