A study on the use of tea (Camellia sinensis) flower extract in the feed of rainbow trout (Oncorhynchus mykiss): Growth, body composition, and hematological blood parameters

Abstract

This study investigated the effects of supplementing rainbow trout (Oncorhynchus mykiss) feed with tea flower (Camellia sinensis) extract (TFE) on growth performance, body composition and hematological blood parameters. A total of 360 rainbow trout with a mean length of 12.2±0.21 cm (min 11.5 cm, max 13.00 cm) and a mean weight of 20.3±0.26 g (min 18.00 g, max 22.00 g) were used in the experiment. The fish were distributed into 12 fiberglass tanks, each with a volume of 100 L (adjusted to 80 L), equipped with a flow system (water flow rate of 9 L/min) and air support. Thirty fish were placed in each tank. The study involved supplementing a commercial trout feed with TFE at four different concentrations: 0 mL/kg (control), 10 mL/kg (TFE-10), 20 mL/kg (TFE-20), and 40 mL/kg (TFE-40). Each treatment group was replicated three times and randomly assigned to the tanks. The results demonstrated that the TFE-10 group exhibited significantly higher final body weight, weight gain, weight gain rate, specific growth rate, feed conversion ratio, protein efficiency, survival rate, and meat yield compared to the control group (P<0.05). Additionally, TFE supplementation was found to increase the protein content and reduce the fat content in the fish flesh. Hematological analysis revealed that all blood parameters, except for platelet count (PLT), were significantly higher in the TFE-10 group compared to the control group at the end of the study (P<0.05). Based on cubic polynomial regression analysis, the optimal TFE supplementation level for maximizing fish growth was calcula ted to be 12.3 ± 3.81 mL/kg.