ESTIMATION OF THE DAILY RATION OF FINGERLING SEA BASS, DICENTRARCHUS-LABRAX, USING A RADIOISOTOPE METHOD

A previously developed method for the estimation of the daily ration o f fingerling sea bass, based on the counting of radioactivity after fe eding an (IAg)-I-125-labelled diet, was further studied in 1.25 g fing erlings of the same species. Fish were fed separate meals of three exp erimental diets differing only in protein source. Labelled diets were offered instead of regular diets in order to estimate feed intake. Rad ioactivity was measured individually on the whole body of 15 fish per group using a gamma-counter and feed intake was calculated using stand ard equations established for samples of labelled feeds. Maximal volun tary ingested ration and maximal daily ration were then calculated. Th e maximal daily ration was found to be 3.5% of body weight irrespectiv e of protein source. This method is very rapid and permits estimations of the above parameters which corroborate other measurements and have a low standard deviation.