The use of X-Radiography for the return of appetite measurements in rainbow trout (Oncorhynchus mykiss Walbaum, 1792)

Abstract

Abstract Quantification of return of appetite in fish is considerably important with respect to the estimation of optimum feeding protocols, Therefore, 30 adult female rainbow trout (0. mykiss) (205.6 ± 2.2 g) in a fresh water recirculation system were fed the control diet containing 42.6% of digestible protein and 19.7 MJ kg'' of digestible energy until all fish were satiated. The fish were re-fed at different time intervals (t= 0, 4, 8, 12, 24 and 48 hours) with the test diet containing radio-opaque glass beads `ballotini' (0.6-0.9 mm) and X-rayed. The amount of feed consumed by fish for each time interval was calculated following the quantification of the number of glass beads in the developed X-ray sheets and the appetite revival of trout was modelled. According to the results, the appetite revival data was best explained by a sigmoid model since the model gave a higher correlation coefficient with a lower residual mean square. The times for 50 and 95 % of return of appetite in rainbow trout were observed as 17 and 43 hours, respectively. It was suggested that the X-radiography technique for the sequential feed intake measurements could he used to understand feeding behaviour of cultured fish species in order to obtain maximum growth performance and. feed efficiency.

Keywords

• Key words: Rainbow trout, return of appetite, X- radiography