Effects of different dietary protein/energy ratios on growth, feed utilization and meat quality of Ctenopharyngodon idella (valenciennes, 1844)

In this study, the effects of different dietary protein/energy ratios on the growth (live weight gain, relative growth rate, daily spesific growth rate, condition factor and vicerosomatic index), feed utilization (feed intake, feed conversion ratio, protein efficiency ratio, protein productive value, apparent digestibility ratios of nutrients and energy in the experimental feeds) and meat quality (crude protein, fat, ash, fiber, nitrogen free extract, moisture and total energy) of fry Ctenopharyngodon idella were investigated. For this purpose, experimental diets 1, 2, 3, 4, 5, 6, 7, 8 and 9 were prepared at the protein/lipid ratios 30/10, 30/15, 30/20, %35/10, 35/15, 35/20, 40/10, 40/15 and 40/20, respectively. Three replicates were conducted for each trials. Feeding rate was calculated as the feeding coefficient and percentage of the live weight was given to fishes three times in a day during 5 months at 22±2 oC of water temperature. At the end of this study, there was a significant differences between experimental groups in the live weight gain, relative growth rate, daily spesific growth rate, condition factor, feed intake, feed conversion ratio, protein efficiency ratio, protein productive value and feed costs for 1 kg fish produce (p<0.05). The best results for these parameters were obtained from 6 numbered experimental group that was followed by test groups 9, 3, 8, 5, 7, 4, 2 and 1 respectively. On the other hand, there was not determined a significant differences between the apparent digestibility ratios of crude protein, fat, ash, fiber, nitrogen free extract, dry matter and energy in the experimental diets (p>0.05). There was a significant differences between the crude fat, ash, fiber and nitrogen free extract values in the fish meat of the experimental groups (p<0.05), but these relations were not significant for the crude protein, moisture and total energy in fish meat (p>0.05). It was determined that the 6 numbered diet obtained best results was contained 32.72% digestible protein, 3565 kcal/kg digestible energy and 91.78 mg/kcal digestible protein/digestible energy ratio. Under the light of this study, it is concluded that an increase in the protein level of diet causes an increase in the energy requirement of fry C. idella. In addition, it was found that the diet of fry C. idella has to constitute 32.72 % of digestible protein and 3565 kcal/kg digestible energy. Moreover, it was also found that optimal digestible protein/digestible energy ratio in diet must be 91.78 mg/kcal. Keywords: Ctenopharyngodon idella, fry, diet, protein/energy ratio, growth, feed utilization, digestibility.