Spawning induction in Kutum Rutilus frisii kutum (Kamenskii, 1901) using carp pituitary extract or GnRH analogue combined with metoclopramide

Kutum Rutilus frisii kutum (Kamenskii, 1901), Cyprinidae is an endemic fish of the Caspian Sea. Iranian Fisheries Organization (Shilat) produce up to 200 million fry (1–2 g body weight (b.w.)) to restock the Caspian Sea population annually. Some of these fry are produced by spawning induction in broodfish by carp pituitary extract (CPE). The objective of this study was to assay the effectiveness of the gonadotropin releasing hormone analogue (d ‐Ala⁶, Pro⁹‐Net GnRH) alone or in combination with metoclopramide (MET), a dopamine antagonist, on the percentage of ovulated females, latency period, ovulation index and fertilization success. The following hormone treatments were tested: single injection of 2 mg kg^?1 b.w. of CPE as a positive control, GnRHa alone 20 and 40 μg kg^?1 b.w. and combination of GnRHa and MET as follows: 5 μg+2.5 mg, 10 μg+ 5 mg and 20 μg+10 mg kg^?1 b.w. Negative control group was injected with 0.7% saline. The percentage of ovulated females, ovulation index and fertilization success were 90%, 71.3±1.24%, 68.4±2.3%, respectively, in the group treated with GnRHa+MET at a dose of 20 μg+10 mg kg^?1 b.w. and were significantly higher than those in the positive control (60%, 64.5±0.23%, 69.1±4.5%) (P<0.05). However, the latency period in this group was longer than that in the positive control (P<0.05). Only 20% and 40% fish ovulated in groups that received 20 or 40 μg kg^?1 b.w. GnRHa. No fish ovulated in the negative control.     

Effect of dietary lipid and protein levels with different protein to energy ratios on growth performance,feed utilization and body composition of Rutilus frisii kutum (Kamenskii, 1901) fingerlings

A 3 × 5 factorial design including three lipid levels (100, 130 and 180 g kg^?1 diet, based on dry matter) and five dietary protein levels (370, 420, 470, 520 and 570 g kg^?1 diet, based on dry matter) was conducted to investigate the optimum dietary lipid and protein requirements for Rutilus frisii kutum fingerlings. Triplicate groups of 80 kutum (500 ± 60 mg initial weight) were stocked in 250‐l tanks and fed to apparent satiation thrice daily for 8 weeks. The results showed that the growth performance and feed utilization were significantly (P < 0.05) affected by dietary protein and lipid levels. Weight gain, specific growth rate and feed conversion ratio of kutum improved significantly with increasing protein level from 370 to 470 g protein kg^?1 diet, but there was a significant decrease in growth parameters with increasing protein level from 470 to 570 g protein kg^?1 diet. Also, the higher values of weight gain, specific growth rate and better feed conversion ratio were observed for fish fed diets containing 130 g kg^?1 lipid diet. The results of this study showed that diet containing 420 g kg^?1 protein and 130 g kg^?1 lipid with a P:E ratio of 19.22 mg protein kJ^?1 of gross energy is optimal for kutum fingerlings.     

Synergic Effects of Light Salting,Vacuum Packaging,and Onion Extract on the Quality Retention of Refrigerated Rainbow Trout (Oncorhynchus mykiss) Fillets

This experiment investigated the synergistic effects of vacuum packaging, light salting, and onion extract on the shelf life of rainbow trout (Oncorhynchus mykiss) fillets stored under refrigeration. The chemical, microbial, and organoleptic changes were monitored for up to 18 days in fillets. Total volatile basic nitrogen (TVB-N) and free fatty acid (FFA) values were evident in the order: control (without salting, vacuum packaging, and extract) > air packaged, salted (APS) > vacuum packaged, salted (VPS) > and vacuum packaged, salted, containing 2% and 4% (v/w) onion extract (2% and 4% VPSOE) throughout the storage period. Thiobarbituric acid values in APS groups were higher than control groups. Data from microbial assay showed that treatment with 2% and 4% VPSOE decreased total viable microbial count (TVC) compared with other treatments. APS, VPS, and VPSOE samples remained acceptable for up to 8, 12, and 15 days, respectively. The most suitable indices for determining shelf life of rainbow trout fillets are TVC.     

New data on the ecology of kutum, Rutilus frisii (Nordmann, 1840) from the Caspian Sea

Abstract– In the anadromous cyprinid kutum, Rutilus frisii (Nordmann, 1840) from the Anzali Lagoon, Iran, the following hitherto unrecorded characters were found. The complex life-style of juvenile kutum is reflected directly in their body size and preferred habitat, and indirectly in their growth rate and the formation of scale annuli. The early juveniles did not move downstream to the feeding grounds in the sea as they are supposed to do in populations inhabiting the Caucasian coast of the Caspian sea, but most of them spend one or two years in fresh or brackish water. Moreover, most kutum scales carried one or two juvenile marks. It appears that the time spent in fresh water is inversely proportional to the age of the kutum. On average about 43% of fish 2 years old and older, spent their first year in fresh or brackish water, while 57% spent two years there. The rate of growth in length is substantially different in both groups. Fish that enter the sea in their second year of life grew faster but their life span seems to be shorter than those which spent two years in fresh or brackish water.     

Determination of grapefruit (Citrus paradisi) peel extract bio‐active substances and its application in Caspian white fish (Rutilus frisii kutum) diet: Growth,haemato‐biochemical parameters and intestinal morphology

In this study, total phenolic and flavonoid contents of grapefruit peel extract (GPE) were equal to 117.3 ± 0.3 µg of gallic acid/mg and 39.30 ± 0.1 µg of quercetin/mg respectively. Caspian white fish (n = 180, 4 ± 0.9 g body weight) was fed with supplemented diets, including 0, 6.25, 12.5 and 25 mg of GPE/kg for 60 days at 25 ± 1°C. The growth performance was markedly improved in fish fed with 25 mg/kg of GPE compared to others (p < 0.05). Moreover, fish fed with 25 mg/kg of GPE showed a significant increase in red blood cell (2.65·10⁶ cell/mm³), white blood cell (17.75·10³ cell/mm³), packed cell volume (48%) and haemoglobin concentrations (8.75 g/dl) compared to the control (p < 0.05). However, the highest alanine aminotransferase (140 U/L), alanine transaminase (14.5 U/L), and alkaline phosphatase (18.5 U/L) were observed in control group. Morphological analysis of intestine revealed the highest amount of villus width (8.4 µM), height (32.86 µM) and surface area (342.7 µM²) in fish fed with 25 mg/kg of GPE (p < 0.05). In conclusion, supplementing feed with GPE at 25 g/kg can improve growth performance and haemato‐biochemical parameters of Caspian white fish fry.     

Effects of Ozonated Water Treatment on the Microbial Population,Quality, and Shelf Life of Shucked Oysters (Crassostrea plicatula)

An ozonated water treatment system was designed for the sanitation of shucked oysters (Crassostrea plicatula). The effects of ozone (O₃) on shelf life were examined under refrigerated conditions (4 ± 1°C). Microbiological, chemical, and color quality were also evaluated by determining total aerobic plate counts (APC), total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), and L, a, and b values. Single and orthogonal experiment results showed that oysters treated with 9 mg/L of O₃ in aqueous solution (oyster: ozonated water = 1:6, w/v) for 10 min at 5°C significantly reduced the total APC by about 2-log—from 4.97 ± 0.11 to 2.93 ± 0.17 log CFU/g (p < 0.05). O₃ treatment did not cause significant changes in TVB-N, TBA, a, and b values, although L values were significantly affected. During refrigerated storage, O₃-treated samples expressed lower TVB-N, TBA, a, and b values and higher L values than control samples. The shelf life of O₃-treated samples was 20 to 25 days, while that for the controls was 5 to 10 days. The current study confirms that treatment with ozonated water can effectively prolong the shelf life and maintain the quality of oysters.