RNA: DNA Ratio, Protein Profile and Growth Rate Ofrainbow Trout (Oncorhynchus Mykiss) Larvae Fed With Varied Proportion of Dietary Protein

Abstract

Biochemical analysis, which determines the quantities of chemical constituents serving as energy substrates, could be one of the indicative measures to show changes of nutritional condition. Among the biochemical indices, the ratio of RNA: DNA has been proven as a useful and reliable indicator of nutritional condition and growth of fishes. The present study was carried out to determine the effects of dietary protein on growth performance, protein profile and RNA: DNA ratio of the Rainbow Trout (Oncorhynchus mykiss Walbaum, 1792) larvae. Eight week old Rainbow Trout larvae were used for the experiment and divided in three fed with : commercial diet; diet containing 40% protein and diet containing 50% protein respectively twice (at 9:00 am and 4:00 pm) a day. Forty fish weighing 0.1846 ± 0.0055 g were placed in each of the three experimental raceways and were fed with one of the experimental diets for 6 weeks consisting of three replicates of each. All records were taken at seven days interval. Protein profile and RNA: DNA ratio was analyzed spectrophotometrically. The results showed higher growth and better feed conversion ratio in experimental group fed with 50% protein diet. The results also confirmed that the protein content and RNA: DNA ratio were all higher in larvae fed with 50% protein diet compared to larvae fed with other two diets indicating that dietary protein concentration has a great influence on growth, protein profile and RNA: DNA ratio as physiological index in Rainbow Trout larvae.