Effect of dietary iron concentrations on growth, hematological parameters, and lipid peroxidation of soft-shelled turtles, Pelodiscus sinensis

Abstract

A feeding trial was conducted to evaluate the effects of dietary ferric citrate supplementation on the growth, hematological parameters, and lipid peroxidation of juvenile soft-shelled turtles, Pelodiscus sinensis. Juvenile soft-shelled turtles (mean initial body weight 5.06 g) were fed diets supplemented with 0, 50, 100, 150, 200, 250, 350 or 450 mg/kg diet as ferric citrate for 8 weeks. The analyzed dietary iron contents were 57.5, 103.6, 139.1, 162.8, 242.6, 280.8, 366.7, and 474.8 mg/kg for the diets supplemented with 0, 50, 100, 150, 200, 250, 350, and 450 mg iron/kg, respectively. Growth, feed conversion ratio, and protein efficiency ratio were lowest for the turtles fed the basal diet with no supplemental iron. Tissue iron content and hematological parameters including red blood cell counts (RBC), hemoglobin (Hb), hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) of the turtles fed basal diet were significantly ( P < 0.05) lower than other groups. Muscle proximate composition was not ( P > 0.05) affected by the dietary iron level. Thiobarbituric acid-reactive substances (TBARS) increased significantly in both muscle and liver tissues when dietary iron level reached 280 mg/kg. Regression modeling using tissue iron contents and hematological parameters as the dependent variables indicated that the optimal dietary iron requirement for soft-shelled turtles was approximately 266–325 mg/kg using ferric citrate as the dietary iron source.