Recent update on the prevalence of Vibrio species among cultured grouper in Peninsular Malaysia

Vibrio infections are common among marine fish and lead to serious problems in the aquaculture sector. This study reports a recent occurrence of Vibrio species (spp.) isolated from cultured groupers in Peninsular Malaysia using the gyrB and pyrH genes. A total of 147 Vibrio strains were successfully isolated from 77 (64%) groupers using culture method and subjected to gyrB and pyrH sequencing for species identification and confirmation. Results showed that 89% of Vibrio strains were identified and clustered to six groups of Vibrio spp., while 11% were not clustered to any Vibrio spp. using the gyrB sequences. Meanwhile, by analysis of the pyrH sequences all the 147 Vibrio strains (100%) were successfully identified and clustered into 11 groups of Vibrio spp., including the gyrB non‐identified strains. The pyrH gene provides a better resolution for identification of Vibrio spp. compared with the gyrB gene. Thus, the pyrH gene was more suitable for a rapid determination of Vibrio spp. distribution in Peninsular Malaysia. Using the pyrH gene, our study found higher prevalence of Vibrio vulnificus (33%), V. alginolyticus (24%) and V. parahaemolyticus (22%), followed by V. rotiferianus (5%), V. harveyi (3%), V. tubiashii (2%), V. campbellii (2%), V. ponticus (1%), V. diabolicus (1%), V. owensii (1%) and others Vibrio sp. (7%). Thus, the results of this study revealed that the occurrence of pathogenic vibrios among grouper fish is still high in Malaysian aquaculture. In addition, the pyrH gene was proved as a suitable marker for rapid identification of Vibrio species compared with the gyrB gene.     

工业和住宅污泥对大叶相思种子萌发以及幼苗生长参数的影响

在孟加拉国吉大港大学林业与环境科学院苗圃内,评价了污泥对大叶相思种子萌发以及幼苗生长的作用。播种前,将污泥与营养匮乏的自然林土壤按不同比率混合,分别在播种后的第1,2和3个月时,记录种子萌发情况和幼苗生长参数（枝条和根系的长度、直径、枝条的鲜重和干重、根和总的干物质量）。在播种前和幼苗采收后,分别测定各个处理的污泥-土壤混合物的理化参数（pH值、有机碳、氮、磷、钾）,以及重金属含量（铬、镍、锰、镉、锌）。结果表明,与对照相比,污泥-森林土壤混合物中播种的种子萌发率和幼苗生长参数发生显著变化。土壤-污泥按2：1混合时,种子萌发率最高（90%）,幼苗生长速率和生物量最大,有机碳和氮磷钾含量也最高。混有工业污泥的土壤中重金属含量要高于混有住宅污泥的土壤。在工业污泥土壤中,污泥-土壤按1：1混合时,重金属含量最高。据此推荐,在退化森林土壤中,土壤-污泥以2：1混合较适合大叶相思种子萌发和幼苗生长。     

Impact of Wall Material on the Physiochemical Properties and Oxidative Stability of Microencapsulated Spray Dried Silver Carp Oil

This study aimed to microencapsulate silver carp oil by spray drying with different combinations of wall materials (gum Arabic, modified starch Hi-cap, maltodextrin, and inulin) and evaluate the effects of these combinations on the physiochemical and oxidative stability of the microcapsules. Feed emulsions were also investigated prior to spray drying. Modified starch-based microcapsules had higher encapsulation efficiency (91.22-92.78%) and yield (87.41-92.15%), excellent solubility (91.85-93.67%), good particle size (301.20-407.73 d.nm), color, and powder morphology. The presence of inulin reduced agglomeration in powders. All the powders exhibited good protection against lipid oxidation during 2 months of storage, whereas the modified starch and inulin combination provided the best stability.     

Sodium alginate supplementation modulates gut microbiota,health parameters,growth performance and growth‐related gene expression in Malaysian Mahseer Tor tambroides

This study investigated the effects of sodium alginate supplementation on gut microbiota composition, health parameters, growth performances and growth‐related gene expression of Malaysian mahseer. Five test diets were formulated by supplementing 0%, 0.1%, 0.2%, 0.4% and 0.8% sodium alginate. Triplicate groups of juvenile Tor tambroides (2.19 ± 0.05 g) were stocked in 15 aquaria (20 individuals per aquarium) and fed at 3.0% body weight per day for 60 days. PCoA and UPGMA analysis showed that gut bacterial community were more convergence in higher sodium alginate‐supplemented diets. The percentage of Porphyromonadaceae, Bacteroides, Plesiomonas and Shewanella were substantially higher and Aeromonas, Entomoplasmatales and Prevotellaceae were drastically lower in higher sodium alginate (0.2%–0.8%) diets. Sodium alginate supplementation (≥0.2%) significantly improved the haematocrit value and respiratory burst activity of T. tambroides. Growth performances and feed utilization were significantly higher in 0.2%–0.4% sodium alginate‐supplemented diets. The increased growth rate of T. tambroides was governed by both hyperplastic and hypertrophic muscle growth. Real‐time PCR data demonstrated that most of the growth‐related genes were significantly upregulated in 0.2%–0.4% sodium alginate‐supplemented diet. Finally, it can be concluded that sodium alginate should be supplemented at 2 g/kg in practical fish feed formulation.     

Simultaneous Extraction and Fractionation of Fish Oil from Tuna By-Product Using Supercritical Carbon Dioxide (SC-CO2)

ABSTRACT

Fish oil was extracted and simultaneously collected into six fractions based on molecular weight and the chain length of triglycerides in terms of fatty acid constituents without splitting of the triglycerides, using supercritical carbon dioxide (SC-CO₂) at optimized conditions of 40 MPa, 65°C, and a flow rate 3 mL min^?1. In each type of fractionation, the first fraction (F1) was rich in saturated fatty acids (SFA; 52.57 to 61.26%), followed by monounsaturated fatty acids (MUFA; 22.17 to 23.22%) and polyunsaturated fatty acids (PUFA; (0.54 to 20.37%); the sixth fraction (F6) was rich in PUFA (48.93%), followed by MUFA (33.59%) and SFA (13.61%). It was obvious that short-chain fatty acids were extracted at an earlier fraction; therefore, the latter fractions were dominant in long-chain fatty acids, especially MUFA and PUFA. Thus, omega-3 fish oil (last three fractions) was successfully separated to be used as a value-added health product.     

Evaluation and characterization of a novel probiotic Lactobacillus pentosus PL11 isolated from Japanese eel (Anguilla japonica) for its use in aquaculture

In the present study, a potential Lactobacilli probiotics were isolated from Japanese eels (Anguilla japonica) and characterized and evaluated for their possible use in eel farming. Sixteen Lactobacilli were isolated from intestines of Japanese eels, using selective media. The lactobacilli strains (represented as PL1 to PL16) were screened by their ability to produce digestive enzyme. Among these, three strains (PL11, PL13 and PL16) producing four digestive enzymes (amylase, cellulase, protease and phytase) simultaneously were characterized further using API ZYM kit. From these, PL11 (Lactobacillu (L.) pentosus) was identified as potential probiotics candidate producing 15 enzymes among 20 tested. Further examination of biological activities of PL11 revealed tolerance against pH, artificial bile juice and antibacterial activity against several fish pathogenic bacteria. The in vitro competitive exclusion assay also revealed 88.4% reduction in adhesion of fish pathogen (Edwardsiella tarda) by PL11 to host intestinal mucus. In vitro incubation of Japanese eel foregut with Baclight‐labelled PL11 showed colonization of the enterocyte surface by confocal and scanning electron microscopy. In summary, PL11 isolated from eels could serve as a potential probiotics with acid and bile tolerance, production of digestive enzymes, antibacterial activity and inhibition of fish pathogen adhesion to intestinal mucus.     

Evaluation of clinical examination for differential diagnosis of lameness by navicular apparatus or heel pain in horses

To evaluation of clinical examination for differential diagnosis of navicular region pain from other forms of palmar heel pain in the forelimb in horses the present study was undertaken. Thirty four horses with lameness referable to the palmar aspect of the hoof based on their response to the palmar digital nerves analgesia were divided into 2 groups based on their response to both distal interphalangeal joint and navicular bursa analgesia. Horses that were profoundly improved by both analgesic blocks (distal interphalangeal joint and navicular bursa) were considered to have navicular region pain whereas, all other horses were considered to have other cause of palmar heel pain. The responses to various diagnostic tests such as hoof tester, distal limb flexion and toe wedge tests were compared between the groups. For all diagnostic tests, sensitivity, specificity and positive predictive values for navicular pain were calculated. According to the present study the single most accurate diagnostic test was analgesia of the distal interphalangeal joint for navicular region pain.     

Evaluation of limb autotomy as a promising strategy to improve production performances of mud crab (Scylla olivacea) in the soft‐shell farming system

Soft‐shell crab, a newly moulted crab having non‐calcified and hydrated soft exoskeleton, farming has been increasing tremendously in recent years throughout the world due to its high market price and consumer preferences. However, high aggressiveness and cannibalistic behaviour of mud crab limit its culture to an individual chamber system which ultimately makes the soft‐shell mud crab farming space and labour‐intensive. Therefore, the aim of this study was to improve the efficiency of soft‐shell crab production by autotomy of the claw and/or walking legs to reduce the moulting duration and intensify the culture system through double stocking in the existing individual chamber culture system. To achieve our objectives, a series of experiment were conducted at both indoor and on‐farm levels by removing the claw and/or walking legs of Scylla olivacea for two consecutive moulting cycles. Results showed that both claw ablation significantly (p < .01) shortened the moulting duration and increased the carapace width, weight gain, specific growth rate, feeding efficiency and yield parameter compared to the non‐ablated crabs more prominently at 1st moulting than the 2nd moulting in both indoor and on‐farm trials. Ablation of all walking legs while keeping the claw intact did not significantly influence (p > .05) the moulting duration and carapace width, but significantly (p < .01) improved the specific growth rate, weight gain, feeding efficiency and yield parameters at 1st moulting compared to the non‐ablation and unilateral three walking leg ablation groups. However, ablation of all appendages (both claw and walking legs) showed significant (p < .01) improvements of carapace width, weight gain, specific growth rate, feeding efficiency and yield parameters, and shortened the moulting duration up to 23 days from 34 days during 1st moulting and up to 27 days from 40 days at 2nd moulting. The survivals of different autotomized mud crabs were statistically non‐significant (p > .05) to the non‐autotomized crabs in various indoor and on‐farm trials. Besides improving the production performances, ablation of bilateral claw and all appendages allowed to double the stocking density in the existing individual chamber‐based soft‐shell crab farming that enhanced the production about threefold higher than the existing individual chamber‐based culture system. Finally, our results suggest that autotomy could be a promising technology for the commercial farming of soft‐shell mud crab in near future.