Effects of Dietary Salbutamol on Growth and Body Composition of Rainbow Trout (Oncorhynchus mykiss Walbaum). {Oncorhynchus mykiss Walbaum)

Abstract

Salbutamol is a beta adrenergic agonist which reduces carcass fat and increases muscle mass and feed conversion efficiency in pigs. In the present study, the effects of dietary salbutamol at 20 ppm on growth, feed conversion ratio, carcass recovery, visceral organ weight, and whole carcass composition were studied. Eighteen months-old rainbow trout (initial weight 324 g) in 2*3 completely randomized design were fed either basal diet or basal diet + 20 ppm salbutamol diet for four weeks. Growth performance was measured weekly. At the end of the four week feeding period, fish were killed, eviscerated and whole carcasses were analyzed for protein, fat and ash. Dietary salbutamol had no adverse effect on fish mortality, health or feed intake. Dietary salbutamol had no significant (p>0.05) effect on growth performance and feed conversion rstio of rainbow trout but significantly increased (p<0.01) the carcass recovery. Internal organ weights such as liver, heart, gonads and viscero-somatic index and hepatosomatic index were also not affected by salbutamol. Interestingly, 20 ppm dietary salbutamol significantly (p<0.01) increased the weight of the kidney possibly, due to increased metabolic load on kidney and blood flow to the kidney. Whole carcass contents of protein, fat and ash of the fish showed no significant difference between treatments and clearly reflected the normal allometric growth and body composition. It was concluded that dietary salbutamol at 20 ppm level had no repartitioning effect in growing rainbow trout. However it is suggested to study the effects of salbutamol at various doses in more mature rainbow trout.