Effect of Feeding Rate on Growth Performance, Feed Utilization, and Blood-Chemistry Indicators of Nutritional Status in Juvenile Gift Strain Tilapia (Oreochromis Niloticus L.)

Abstract

This study investigated the effect of feeding rates (2-10% of body weight), on the growth performance, feed utilization, and blood-chemistry indicators of nutritional status in juvenile GIFT strain tilapia, (Oreochromis niloticus) initial weight 72.73±0.15g. The 56 day trial conducted in cages tested five groups, with three replicates each. Fish were fed twice a day. Data were analyzed using one way ANOVA. Results showed that final body weight, food conversion rate (FCR), weight gain, specific growth rate (SGR), protein retention efficiency (PRE), protein efficiency ratio (PER), feed intake, and condition factor (CF) were significantly affected by the feeding rates (P<0.05). The broken line method of linear regression analysis, y=17638x-217.9, R²=0.945; y=280x+860.6, R2=1, indicated that maximum weight gain occurred at 6.21% feeding rate. Insulin growth factor-one (IGF-I) level, hepatosomatic index (HSI), white blood cell (Wbc), red blood cell (Rbc), hemoglobin (Hb), and hematocrit (Ht) parameters were not significantly affected by the feeding rates (P>0.05). Serum indicative parameters of liver-enzyme functions and food metabolism, including blood glucose (GLU), triglyceride (TG), total protein (TP) levels, aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) enzyme activities were assayed. Blood glucose level of the fish was significantly affected by the feeding rates (P<0.05). TG and TP levels; AST, ALT and ALP activities were not significantly affected by the feeding rates (P>0.05). Feed provided at a rate of 2%-10% of body weight may meet physiological wellbeing of GIFT strain tilapia, however growth performance and other endocrine functions (IGF-I) are affected by lower and higher feeding rates. Our findings could be very useful to tilapia farmers.