The aim of this study was to investigate how various diets influence testis maturation stages in mud crab (Scylla olivacea)
broodstock. Morphological and histological assessments were performed in triplicate (10 male crabs each). Daily,
subject crabs were fed a squid (Loligo sp.) and a fish (Decapterus sp.) diet at 5-10% of body weight. Diets were analyzed
following methods from the Association of Analytical Communities (AOAC). In comparison to control (wild) crabs, the
two diets generally did not cause significant differences (p>0.05) in body weight, carapace width and gonadosomatic
index (GSI), except in the GSI of squid-fed crabs (p<0.05). At the end of the experiment, crabs that reached Stage 3 testis
maturation included were 6 fish-fed individuals and 23 squid-fed individuals. Additionally, differences in crude protein
and fat levels across diets influenced the nature of male gonadal development. In conclusion, a squid diet was sufficient
to induce Stage 3 testis maturation in Scylla olivacea within 60 days of culture. Our results prove the usefulness in
developing appropriate feeding regimes for male Scylla olivacea broodstock.
The objectives of this study were to determine the effect of different cryoprotectants and sperm densities for longterm storage of orange mud crab, Scylla olivacea spermatozoa. Spermatozoa were obtained by homogenizing the spermatophores using a glass homogenizer in an ice-bath followed by centrifugation at 4°C. Spermatozoa were then suspended in calcium-free saline (Ca-F saline) containing 5% of the following cryoprotectants: Glycerol, dimethyl sulfoxide (DMSO) and methanol. Sperm which vibrated and rotated were counted as live during sperm viability assessment. Samples of spermatozoa were cooled to -196°C by two-step freezing, first to -80°C and then by plunging into liquid nitrogen (LN). Spermatozoa were gradually cooled at 1°C/min. Thawing was carried out in a 30°C water bath for 2 min. This yielded live sperm after storage in LN for 30 days. The best sperm viability was obtained from a density of 108 cells per mL in DMSO. There was no significant difference (p>0.05) among cryoprotectants toward sperm viability. However, sperm viability was significantly affected (p>0.05) by cell densities. In conclusion, DMSO gave the best protection to sperm cells of S. olivacea, but the effectiveness of DMSO as a cryoprotectant is influenced by sperm density.