Effects of Dietary Star Apple (Chrysophyllum cainito L.) Peel Extract on Growth Performance, Intestinal Histology, Hematology, and Non-Specific Immune Parameters in Common Lowland Frog (Rana rugulosa Wiegmann)

Star apple (Chrysophyllum cainito L.) has been used to treat several diseases. However, using this plant as a feed additive in aquaculture production is rare. Therefore, this work aimed to investigate the effects of dietary star apple peel extract (SAPE) on growth performance, intestinal histology, hematology, and non-specific immune parameters in common lowland frog (Rana rugulosa Wiegmann). Peel samples from star apple fruits were collected, dried, and extracted with methanol. Alkaloids, flavonoids, phenolics, saponins, tannins, and steroids were detected in SAPE at varied concentrations. Frogs of average weight 8.50 ± 0.10 g were fed diets incorporating 0, 10, 15, and 20 g SAPE/kg diet. After six weeks of feeding, the frogs' growth and physiological parameters were evaluated. The results revealed that the growth and intestinal histology features of frogs fed SAPE diets were significantly increased compared with the control (P <0.05). No significant differences among the treatments were observed in the survival rate, red blood cells, hematocrit, and hemoglobin (P >0.05). Serum albumin was significantly enhanced in frogs fed a 10 g SAPE/kg diet (P <0.05). Dietary SAPE significantly decreased serum alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, triglyceride, and cholesterol compared with the control (P <0.05). Furthermore, frogs fed SAPE diets had significantly elevated lysozyme activity, leukocyte respiratory burst activity, complement activity, and immunoglobulin M compared with the control (P <0.05). In conclusion, these results showed the beneficial effects of SAPE on the growth and health status of frogs with the appropriate level of 17.75 to 20.00 g/kg diet. Keywords: Medicinal plants, Common lowland frog, Growth performance, Immunity, Hematology