Hematology and clinical chemistry of adult yellow-headed temple turtles (Hieremys annandalii) in Thailand

Background: Yellow‐headed temple turtles (YHT), Hieremys annandalii, native to Thailand, are protected from exploitation under the Wild Animal Reservation and Protection Act, also listed under Appendix II of the Convention on International Trade of Endangered Species and the International Union for the Conservation of Nature red list. Objectives: The objectives of this study were to describe quantitative, morphologic, and cytochemical features of blood cells and plasma biochemical analytes of clinically healthy YHT. Methods: Blood samples were collected from 40 adult YHT from October 2007 to February 2008. Hematologic and biochemical analyses, cytochemical staining, and ultrastructural evaluation were performed using standard methods. Results: Hematologic results (mean ± SD) included: RBC count, 0.275 ± .094 × 10⁶ cells/μL; WBC count, 11.7 ± 6.6 × 10³ cells/μL; heterophils, 29.4 ± 6.9%; eosinophils, 23.7 ± 5.3%; basophils, 21.2 ± 1.9%; lymphocytes, 14.8 ± 5.9%; and azurophils, 10.7 ± 5.3%. Erythrocytes stained dark red with peroxidase‐staining. Periodic acid‐Schiff stain could not differentiate between thrombocytes and lymphocytes. Thrombocytes contained cytoplasmic vacuoles, similar to mammalian platelets and those of birds and snakes. Heterophils and eosinophils were similar in structure and cytochemical staining characteristics to those of other turtles and reptiles. Structure of basophils was similar to avian basophils. Lymphocytes and azurophils had similar cytochemical staining compared with mammalian lymphocytes and monocytes. Mean MCHC, WBC counts, absolute azurophil counts, and plasma alanine aminotransferase activity were higher in male turtles than in females. Conclusion: Blood characteristics of YHT are species‐specific, and this study can be served as a reference for future clinical studies and medical care of YHT.     

Effect of Astaxanthin on the Pigmentation of Goldfish Carassius auratus

The optimal dosage of astaxanthin for goldfish Carassius auratus was determined by feeding a series of diets containing 0, 25, 50, 75, and 100 mg of astaxanthin/kg of diet for 4 wk. The pigmentation on fish skin was measured by visual assessment against a color chart and by counting chromatophores produced in the dermis layer of fish skin. Both criteria showed that 36–37 mg/kg astaxanthin was the optimal dosage to stimulate fish color. A 4-wk observation after this experiment demonstrated that fish color stimulated by dietary astaxanthin was stable in its intensity. Therefore feeding astaxanthin could be a suitable way for goldfish producers to stimulate color among fish grown in an algae-free environment. The survival rate of fish fed diets with astaxanthin was significantly higher than fish fed diets without astaxanthin. However, there was no significant effect of astaxanthin on fish weight gain.     

Antiviral activities of Clinacanthus nutans (Burm.f.) Lindau extract against Cyprinid herpesvirus 3 in koi (Cyprinus carpio koi)

Cyprinid herpesvirus 3 (CyHV‐3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well‐known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract against human herpes simplex virus have been reported. In this study, C. nutans crude extract was tested for antiviral activities against CyHV‐3 in koi carp. Results showed effective antiviral activity against CyHV‐3 pre‐ and post‐infection. The 50% lethal concentration (LC₅₀) of extract was higher than 5 mg/ml. The 50% effective dose (ED₅₀) was 0.99 mg/ml, 0.78 mg/ml, 0.75 mg/ml and 0.71 mg/ml at 1, 2, 3 and 4 hr pre‐infection, respectively. The ED₅₀ from post‐infection tests was 2.05 mg/ml and 2.34 mg/ml at 0 and 24 hr, respectively. These results demonstrated that crude extract expressed antiviral activity against CyHV‐3 and can be applied as a therapeutic agent in common carp and koi aquaculture.     

Modulation of intestinal morphology and immunity in nile tilapia (Oreochromis niloticus) by Lactobacillus rhamnosus GG

The use of lactic acid bacteria from human origins as a potential probiotic supplementation in aquaculture feed is now widely accepted. Here, we examined some of the properties and mechanisms of the action of Lactobacillus rhamnosus GG, originating from humans, on growth performance, gut mucosal immunity and humoral and cellular immune response in tilapia (Oreochromis niloticus). The results suggested that supplementation of L. rhamnosus gave an advantage in promoting the intestinal structure and the mucosal immunity of tilapia. Probiotic fish had a greater villous height in all parts of the intestines and, significantly, in the proximal and middle part. The population of intraepithelial lymphocytes was significantly higher in the probiotic group than in the control group in all parts of the intestines. The population of acidophilic granulocyte in the probiotic group was significantly higher at the proximal and distal parts when compared with the control group. The higher serum complement activity as well as the enhanced phagocytosis and killing ability of the head kidney leukocytes in the probiotic supplemented fish corresponded with the higher level of TNF alpha and IL-1 gene expression, suggesting that the induction of IL-1 and TNF alpha cytokines by L. rhamnosus served as an important regulator of gut associated immune systems.