EFFECTS OF RESTRICTED FEEDING ON PERFORMANCES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS)

Abstract

Rainbow trout (104.8±0.15g), Oncorhynchus mykiss, were fed a commercial extruded pellet for 7 weeks to investigate the effect of restricted feeding on performances. Three restricted feeding were tested: two day intervals (TDI), every other day (EOD) and twice a day (TD). Fish were held in fresh water at 9-13°C from January 16 to March 4, 2004. Feed conversion rate (FCR) were TDI and TD groups 1.33±0.03 and EOD group 1.54±0.03, protein efficiency ratio (PER) were TDI group 1.88±0.04, EOD group 1.59±0.03 and TD group 1.85±0.04, respectively. Although FCR was the same between TDI and TD, there was a significant differences in weight gain, relative growth rate (RGR) and specific growth rate (SGR) between the groups. These group evaluated the food at the same rate but since the given food amount were different, the weight gain, SGR and RGR of TD were the highest dependent to the food amount. Although the FCR was good in restricted fed fish, the taken feed amount sigificantly affected the growth parameters of fish. Relative growth rate (RGR), weight gain and specific growth rate (SGR) were lower in TDI and EOD groups. Both specific growth rate and relative growth rate increased with number of restricted feeding. The restricted feeding influenced the chemical composition of the fish. The lipid, moisture and protein content of fish increased when the fish were fd twice a day (TD group). In terms of SGR and RGR, it can be concluded that the best growth rate was obtained from the fish fed twice a day (TD) and every other day (EOD) feeding for rainbow trout at 9-13oC.