Abstract
The present study investigated the effect of body weight on body composition, digestive and absorptive capacity, transaminase activities in hepatopancreas and muscle, and plasma ammonia concentration of Jian carp (Cyprinus carpio var. Jian). A total of 750 Jian carps (18.0 ± 0.2 g) were randomly distributed into five groups with three replicates and fed the same diet for 56 days. Tissue and plasma samples were collected on days 14, 28, 42, and 56. The results were used to develop a mathematical model for specific growth rate, body moisture and fat content, aspartate transaminase activity and alanine aminotransferase activity in hepatopancreas and muscle, plasma ammonia concentration, and trypsin, chymotrypsin, lipase, and amylase activities in hepatopancreas and intestine, activities of creatine kinase, Na+/K+-ATPase, alkaline phosphatase, and γ-glutamyl transpeptidase in intestine in Jian carp. There were linear relationships between natural logarithms of above indexes and body weight. The body moisture and fat content, digestive and absorptive enzymes activities, and transaminase activities showed negative allometry against body weight of Jian carp which were partial reasons to explain fish growth rate decreasing.