The fate of chlortetracycline residues in a simulated chicken–fish integrated farming systems

Two experiments were conducted at the Asian Institute of Technology, Pathumthani, Thailand to investigate the fate of chlortetracycline (CTC) residue in chicken manure and its effect on integrated chicken–fish farming system. During the first experiment, broiler chickens were raised and CTC residues in their manure were analysed. Chicken fed diets containing 0, 50, 200 and 800 CTC mg kg^?1 had CTC residue levels of 0, 0.9, 3.8 and 6.5 CTC ng g^?1. Once the diet containing CTC was withdrawn, CTC in the manure dropped to negligible amounts (0, 0, 0.2 and 0.5 CTC ng g^?1) within 1 day. Integrated chicken–fish farming systems were simulated during the second experiment to determine the fate of antibiotic residues in chicken manure in aquaculture environment. Chickens were fed a CTC‐free diet and a feed containing CTC at 200 mg kg^?1. Ten 4 m³ square concrete tanks (2 × 2 × 1 m) were used for the experiment. Five tanks were fertilized with CTC‐contaminated manure and the remaining five tanks were fertilized with CTC‐free manure at a rate of 100 kg dry matter ha^?1 day^?1. Sex‐reversed Nile tilapia (Oreochromis niloticus) was stocked at 12 fish tank^?1 on the 14th day after chicken manure application. The immuno‐radio microbial receptor assay (Charm II test) revealed that edible fish muscle, fish intestinal tract and sediment were contaminated by CTC at rates of 7.21, 22.104 and 1.788 ng g^?1, respectively, after 45 days. Chlortetracycline was detected on day 20 in the water column and gradually increased from 0.26 to 12.13 ng g^?1. Chlortetracycline residues were not detected in fish or the aquatic environment of the CTC‐free treatment. The results demonstrate the potential for antibiotic residue accumulation in fish and aquatic environment when CTC‐contaminated chicken manure is used for pond fertilization.     

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.     

Experimental Study of Heat Transfer in Soil to Inhibit Microbial Growth Using the Underground Release of Hot Water and a Hydraulic Head Method

This research aimed to study the effectiveness of heat transfer in soil using the underground release of hot water with a hydraulic head. Pressure heads of 1.0, 1.5 and 2.0 m were utilized for underground release with a nozzle to investigate heat transfer in soil necessary to inhibit microbial growth through underground hot water release using a pressure head of liquid. The nozzle was made of stainless steel pipe (SUS304). The proposed system was designed to inhibit microbes of Ralstonia solanacearum with a hot water volume flow of 300, 400 and 500 ml min^?1, while temperature was kept constant at 70 ºC. The hot water released underground provided higher soil temperature with shorter working time. The research found that the number of layers and diameter of drilled holes had a significant effect on soil temperature distributed at various depth levels (y-plan), resulting in enhanced performance (100%) for the inhibition of microbes in an x-plan radius of 15 cm for a shorter time of 20–30 min with one nozzle.