EFFECT OF PROPYLENE GLYCOL ON FEED DIGESTIBILITY AND THE GROWTH AND PHYSIOLOGICAL RESPONSE OF RAINBOW TROUT

The effect of supplementing from 0 to 10% propylene glycol (replacing corn starch on an equal weight basis) to a low-energy trout diet on the feed digestibility and the growth and physiological response of rainbow trout was determined. Propylene glycol had no significant effect on the growth, feed:gain ratio, final carcass composition and feed digestibility coefficients of the trout. However, propylene glycol was apparently unstable and/or volatile during feed processing and storage which may have confounded a clear interpretation of the digestibility and growth studies. The trout reared on the 10% propylene glycol supplemented diet also had a slower feeding response than the other groups which may ultimately affect the growth of the trout. It was concluded that propylene glycol was not a cost effective source of dietary energy to the trout and a level of 10% in the diet appeared to be tolerated by the trout. Key words: Trout, propylene glycol, energy, feed utilization, digestibility