Specific enzyme activities of trypsin and chymotrypsin in various age of Tilapia, Oreochromis niloticus, tested at different temperatures

The objectives of this study were to evaluate the effects of age of tilapia (Oreochromis niloticus) and tested temperatures on in vitro enzymes activities of trypsin and chymotrypsin. Extracted enzymes from the intestine of tilapia age 45-140 days were determined specific enzyme activities of trypsin and chymotrypsin at various temperatures between 30-70 ºC and 20-60 ºC, respectively. Expression of specific activities of trypsin (T) and chymotrypsin (C) depended on fish age and tested temperatures. The highest specific activity of trypsin was found in fish aged 105 days using a tested temperature of 70 ºC whereas that of chymotrypsin was observed at fish aged 120 days using 60 ºC. Tested temperatures resulting in the highest specific activities of trypsin and chymotrypsin were detected at 70 ºC and 60 ºC, respectively. The T/C ratio in fish aged 105 days had the highest value, compared to those of other fish age. An increase in tested temperatures resulted in higher T/C ratio. This study allowed understanding of the expression of specific activities of trypsin and chymotrypsin of tilapia at various age, which can be used as the baseline information for further development of suitable feed formulation of tilapia based on in vitro digestibility

Survivability of freeze- and spray-dried probiotics and their effects on the growth and health performance of broilers

Background and Aim: Many strains of probiotics have been exploited and used as animal dietary supplements for broiler production. The efficacy and survival of probiotics during production may reflect better activities of the probiotics in the host. This study investigated the effects of freeze- and spray-drying on the survivability and properties of probiotics and their ability to improve the growth and health performance of broilers. Materials and Methods: Probiotic powders of four strains of lactic acid bacteria, Enterococcus faecium CA4, Enterococcus durans CH33, Ligilactobacillus salivarius CH24, Pediococcus acidilactici SH8, and Bacillus subtilis KKU213, were prepared using rice bran/chitosan/carboxy methyl cellulose as the carrier. The survival of each probiotic strain was investigated under stress conditions, including freeze-drying, spray-drying, and simulated gastrointestinal conditions. The body weight gain (BWG) and intestinal histomorphology were determined to assess broiler growth performance. Results: All dried probiotics yielded a high survival rate during freeze-drying (95.8-98.6%) and spray-drying (94.4-98.2%). In addition, an analysis of the main effect revealed that the effectiveness of freeze-drying was higher than that of spray-drying in minimizing the loss of cell viability. The antimicrobial activity of all immobilized dried probiotic strains against Salmonella was maintained. The immobilized probiotics tolerated a low pH value of 2.0 and 0.5% (w/v) bile salt. Probiotic administration of a mixture of the five dried probiotics to 1-day-old hatched male broilers at early and late ages resulted in potential colonization in the broiler intestine, and enhancements in the BWG, lipid metabolism, and gut health (villus height and cryptal depth) were observed in the probiotic-treated groups. Conclusion: The administration of three doses of the spray-dried probiotic mixture at days 15, 17, and 19 after hatching was sufficient to achieve long-term growth and health benefits in broilers. This finding might provide a cost-effective alternative to the administration of commonly used antibiotics in broiler production

Bacterial Contamination and Decontamination of Cryopreserved Freshwater Fish Milt in Thailand: Case Study of Silver Barb (Barbodes gonionotus) Milt

บทคัดย่อการปนเปื้อนแบคทีเรียเป็นสาเหตุสำคัญที่ทำให้คุณภาพน้ำเชื้อลดลงและสร้างความกังวลต่อความปลอดภัยทางชีวภาพของน้ำเชื้อแช่แข็ง การปนเปื้อนแบคทีเรียในการแช่แข็งน้ำเชื้อเกิดขึ้นได้ในทุกขั้นตอน  โดยเฉพาะอย่างยิ่งขั้นตอนการเก็บรวบรวมน้ำเชื้อ การปนเปื้อนแบคทีเรียส่วนใหญ่มักปนเปื้อนจากน้ำที่ใช้เลี้ยงปลา ครีบก้น และอุจจาระและปัสสาวะของปลา การปฏิบัติตามแนวทางของการปฏิบัติงานที่ถูกสุขอนามัยสำหรับห้องปฏิบัติการสามารถลดการปนเปื้อนแบคทีเรียได้ นอกจากนี้การเก็บรวบรวมน้ำเชื้อโดยการใช้สายสวนร่วมกับการล้างช่องเพศปลาด้วยน้ำปราศจากเชื้อและเช็ดบริเวณช่องเพศให้แห้ง และการไม่นำน้ำเชื้อที่ปนเปื้อนอุจจาระและปัสสาวะมาใช้ในการแช่แข็งยังช่วยลดปริมาณและชนิดของแบคทีเรียในน้ำเชื้อได้อย่างมาก การประยุกต์ใช้ยาปฏิชีวนะผสม 0.25% Penicillin-Streptomycin ในน้ำเชื้อเป็นอีกทางเลือกหนึ่งในการลดการปนเปื้อนแบคทีเรียในน้ำเชื้อแช่แข็งโดยไม่ส่งผลกระทบต่อคุณภาพสเปิร์มและการปฏิสนธิ อย่างไรก็ตามแบคทีเรียก่อโรคบางชนิด ได้แก่ Aeromonas hydrophila subsp. hydrophila และ Pseudomonas fluorescens ยังคงพบได้และดื้อต่อยาปฏิชีวนะผสมทั้งสองชนิดนี้ รวมทั้งสามารถถ่ายทอดจากน้ำเชื้อแช่แข็งไปยังตัวอ่อนของปลาตะเพียนขาวที่เกิดจากการผสมเทียม ดังนั้นควรทำการศึกษาวิจัยเพื่อพัฒนาเทคโนโลยีใหม่ๆ ที่มีประสิทธิภาพในการลดการปนเปื้อนแบคทีเรียก่อโรคในน้ำเชื้อแช่แข็งโดยไม่ส่งผลกระทบต่อคุณภาพน้ำเชื้อต่อไปคำสำคัญ: ปลาตะเพียนขาว แบคทีเรีย การปนเปื้อน น้ำเชื้อแช่แข็ง ABSTRACTBacteria contamination is an important factor of decline in milt quality and creates a concern in biological safety of cryopreserved sperm. Bacterial contamination can occur in every step of cryopreservation processes, particularly, during milt collection. Most contaminated bacteria usually originate from culture water, anal fins, and fecal and urine mixtures. Implementation of a standard sanitation protocol required for minimal bacterial contamination in laboratory is capable of decreasing degree of contamination. Moreover, rinsing urogenital aperture with sterile water and drying urogenital opening prior to milt collection using a catheter, and no use of milt with fecal and urine mixture can dramatically reduce the number and type of bacterial contaminants in cryostored milt. Application of 0.25% penicillin-streptomycin mixture is also an alternative technique for minimizing bacteria contaminants in cryopreserved milt without negative effect on sperm quality and fertilization success. However, some pathogenic bacteria e.g. Aeromonas hydrophila subsp. hydrophila and Pseudomonas fluorescens still remain due to their resistance to these mixed antibiotics and they can be transferred from cryostored milt to artificially inseminated embryos of silver barb. Therefore, development of effective novel technology for decontamination of pathogenic bacteria in cryostored milt without detrimental effect on fish sperm should be further established.Keywords: silver barb, bacteria, contamination, cryopreserved milt

Seasonal Changes in Upper Thermal Tolerances of Freshwater Thai Fishes

Seasonal change inferred to climate change inevitably influences Critical thermal maximum (CTmax) of riverine fishes. In this study, we investigated CTmax as thermal tolerance for four common riverine fishes, i.e., Danio regina, Channa gachua, Rasbora caudimaculata and Mystacoleucus chilopterus, in the Kwae Noi river system in western Thailand. The acute thermal tolerance was lower in the wet season (mean river temperature ∼25 °C) and higher in the dry season (mean river temperature ∼23 °C) with medians of wet season-CTmax for those four fishes of 35.3 ± 0.4, 36.2 ± 0.5, 37.3 ± 0.5 and 37.5 ± 0.6 °C, respectively, and high values of dry season-CTmax of 37.4 ± 0.5, 38.3 ± 0.5, 38.7 ± 0.7 and 39.1 ± 0.5 °C, respectively. The variations of CTmax for all of the four species in this study, throughout the wet and dry seasons, attribute to their seasonal plasticity in response to the dynamics of thermal stress. Under climate variability and climate change with increasing the higher temperatures of air and river, and altering the habitat, R. caudimaculata and M. chilopterus had higher capacities to tolerate the acute heat stress across wet and dry seasons