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Summary: The development of a chilled storage protocol of fish sperm requires an understanding of sperm biology and function as the activation/inhibition of fish sperm is greatly affected by several environmental factors. This study aimed to determine the effects of ionic and non‐ionic solutions, extender types (Ringer's solution, Ca‐F HBSS solution, HBSS solution, He and Wood solution, Saline solution, and Modified Cortland solution), and chilled‐storage period on sperm quality and fertilization ability of Asian seabass, Lates calcarifer semen. Regulation of Asian seabass sperm motility was dependent on the osmolality of both ionic and non‐ionic activation media. The threshold levels on the initiation of sperm motility were detected in KCl (>100 mM), NaCl (>50 mM), CaCl2 (>50 mM), glucose (>300 mM), and mannitol (>100 mM) solutions. Relatively high percentages of sperm motility (>80%) were observed when activated with KCl, NaCl, CaCl2, glucose, and mannitol solutions at above 700, 600, 350, 1,000, and 1,000 mM, respectively. Ringer's solution was the most optimal extender for chilled storage of Asian seabass semen at 2–4°C supported by the retention of sperm motility and viability for 6 days. Semen diluted in Ringer's solution and chilled‐stored for 2 days exhibited acceptable fertilization (66.1% ± 6.2%) and hatching (56.4% ± 2.9%) rates. This report, for the first time, describes the ionicity and non‐ionicity effects on the motility of Asian seabass sperm. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of mixed Bacillus on growth, water quality and disease resistance against Vibrio harveyi in whiteleg shrimp (Litopenaeus vannamei). Postlarval shrimp (PL30) were fed with (a) a basal diet (the control), (b) a diet containing mixed freeze‐dried Bacillus probiotics (FB) and (c) addition of mixed microencapsulated Bacillus probiotics (MB) in culture water. Addition of FB and MB probiotics improved (p <.05) growth, feed efficiency, survival and culture water quality (ammonia and nitrite) compared to the control group although there was no difference (p >.05) between the two treated groups. Bacillus numbers in gastrointestinal tracts and culture water of FB‐ and MB‐administrated shrimp were higher (p <.05) than in the control. After a 30‐day culture, shrimp were infected with V. harveyi and monitored for 10 days. A significant reduction (p <.05) in cumulative mortality was observed in FB‐ and MB‐supplemented shrimp (43.24% and 45.05%, respectively), compared to the control (63.06%). This finding demonstrated that administration of microencapsulated probiotics was as effective as freeze‐dried probiotics for improving growth, feed efficiency, survival, Bacillus in gastrointestinal tracts, water quality (ammonia and nitrite) and conferring disease resistance to V. harveyi. [ABSTRACT FROM AUTHOR]

Application of good sanitation practice in cryopreservation process is the key issue to improve the quality of cryopreserved fish sperm. This study implemented standard sanitation protocol with minimal contamination and evaluated the source of bacterial contamination associated with laboratory equipment and related materials across a series of cryopreservation process of silver barb ( Barbodes gonionotus) semen. The use of 16s rRNA sequencing and traditional biochemical methods were performed for bacterial identification. Animal origin (anal fin, culture water and semen contaminated with faeces and urine) and non-animal origin (liquid nitrogen from liquid nitrogen dewar, outer surface of straw, air circulation in cryopreservation laboratory and latex gloves used during cryopreservation procedure) were determined for bacterial contamination. Aeromonas punctata subsp. caviae was the most abundant species in anal fin, latex groves and semen contaminated with faeces and urine. Bacillus safensis and Bacillus sp. were found as frequently recovered species from liquid nitrogen dewar. Aeromonas hydrophila subsp . hydrophila and Pseudomonas fluorescens, fish pathogenic bacteria, were isolated from all animal origin samples. This was the first report indicating that standard sanitation and hygiene methodologies are recommended for sperm cryopreservation of B. gonionotus to prevent bacterial contamination. [ABSTRACT FROM AUTHOR]

Effectiveness and efficiency of frozen sperm on fertilization and hatching success of eggs from silver barb was examined in relation to cryoprotectants, freezing rate and storage period. Sperm was diluted in calcium-free Hank's balanced salt solution, equilibrated with dimethylsulphoxide ( DMSO), propylene glycol, sucrose or methanol at 5%, 10%, 15% or 20% final concentrations, and frozen in 250-μL straws using a one-step freezing procedure (1, 5 and 8°C min−1 from 25 to −40°C). Highest post-thaw sperm motility was found from a treatment using 10% DMSO and 5°C min−1 (82.2 ± 2.1%), similar to that of 10% DMSO and 8°C min−1 (87.8 ± 3.2%). Post-thaw motility of sperm frozen at 5 or 8°C min−1 was significantly higher than 1°C min−1. Relative sperm motility declined significantly after 10 months of cryostorage while viability did not change during a 12-month cryostorage. Average fertilization rates of sperm after 1 and 4 months of storage were 64.5 ± 4.6% and 61.3 ± 3.4%, respectively, similar to those of fresh sperm (69.6-72.3%). Hatching rates of cryopreserved sperm (45.4-51.2%) were similar to those of fresh sperm (51.8-57.8%). This study developed suitable methods for cryopreservation of silver barb sperm that can be used to facilitate hatchery operation. [ABSTRACT FROM AUTHOR]