For commercial aquaculture, the obtainment of all-female salmonid populations is important in fish farms. After freezing process, variable spermatozoa maturity, higher sperm concentration, low sperm quality, and reduced fertilization success have been observed in sex-reversed female rainbow trout. For these reasons, the objective of this study was to assess effect of dilution rate and supplementation of a N-(2-Mercaptopropionyl)-Glycine (MPG)-based extender on sperm motility and fertilizing capacity of sex-reversed rainbow trout (Oncorhynchus mykiss). The supplementation of MPG [0 (control, 0), 1 mM; 2 mM; 4 mM] to extenders and dilution ratio (1:9, 1:15 and 1:25) were tested in sex-reversed female rainbow trout spermatozoa during cryopreservation. For thawing, the straws (0.5 ml) were placed in a water bath at 37°C for 30 s. Our results showed that the best concentration of MPG was 2 mM for post-thaw motility duration (120.67±9.07%), fertilization (62.67±3.10%) and hatching rate (54.33±3.10%) at 1:15 dilution rate. Overall, MPG provided improvements during cryopreservation process and could be used as protective agent.

Rainbow trout (Oncorhynchus mykiss) were examined effects of apricot kernel oil (Prunus armeniaca L.) on the immune mechanisms. After Fish weight 40 ±0,03 g was intraperitoneal (i.p.) injection 1% and 10% apricot kernel oil (AKO), blood was taken from the caudal vein of anesthetized (50 ppm, benzocaine) fish. Myeloperoxidase production (MPO), Serum bactericidal activity, protein levels, Lysozyme response (LYS) and total immunoglobulin (Ig) were determined on days 3, 7, 14 and 21. The same strategy was conducted on a control bunch. No contrasts were found within the levels of immunuglobulin between the control and test groups. However, there were considerable increases in bactericidal activity, MPO, LYS, protein levels and important differences were detected between the control and experimental groups. AKO can be utilized to improve the resistant instruments of rainbow trout.

Sensory quality characteristics of fish are very important factors on acceptance and market value of the product. Quality assessment of fish should be precise, fast, systematic and comprehensive regarding freshness attributes. The objectives of this study were to describe weather the QIM (Quality Index Method) scheme for salmonides can be used to determine the freshness and describe the sensory changes during storage. Quality assessment of the fresh water rainbow trout (n=36) was performed on day 1, 7, 14 and 21 of ice storage on temperatures from 0.6-0.8°C. Through the QIM scheme the specific freshness attribute deterioration can be very well described and the QIM score produced a clear result, which showed that the deterioration of fish is linear and has a strong correlation with the time of storage. The QIM scheme for farmed salmon can be used to evaluate the freshness of the rainbow trout. It can also be used to ascertain and predict the remaining shelf life of rainbow trout stored in ice. Under similar conditions, the maximal shelf life of ungutted rainbow trout is 14±2 days or 15 demerit points of framed salmon QIM scheme.

The aim of this study was to evaluate the activities of the biotransformation enzymes (Glutatyon S-Transferase (GST) and cytochrome P450 (CYP1A1)) and metabolic enzyme (Lactate dehydrogenase-LDH) in the liver of rainbow trout (Oncorhynchus mykiss) after 24 and 48 hour exposure to 0.5, 1.0 and, 2.0 mg l-1 of Congo red (CR). Enzyme activities were determined by using commercial kits with ELISA method. Congo red altered the activities of GST, CYP1A, and LDH enzymes in liver tissue of O. mykiss in a dose-dependent manner. The statistical differences in GST activities among the groups for 24 and 48 h were significant, but, LDH activities were significant for only 24 h. Exposure duration of CR didn’t affect the biochemical response of rainbow trout. Thus, CR exposure changed the biotransformation and metabolic enzymes, and the changes of these enzymes activities may be used as a potential bioindicator of the CR exposure.

In this study, the effect of supplementing amino acid-precursor of nitric oxide (NO) L-arginine were examined on sperm motility of rainbow trout Oncorhynchus mykiss. Different concentrations [0 mM (Control), 1 mM, 2 mM, 4 mM and 8 mM] of L-arginine were used in the study. To assess the effects on percentage of motile sperm and longevity, L-arginine was added to activation medium containing NaCl (52 mM). The higher L-arginine concentration (4mM) has promoting-effect on sperm motility. The treatments containing L-arginine caused significant effect on percentage of motile sperm and longevity. Overall, the findings of the present study indicated that supplementation of L-arginine may have improving effects on sperm motility of rainbow trout.