اثر سطوح ویتامین e جیره‌ غذایی بر عملکرد تولید مثل ماهی ماده شانک زردباله عربی (acanthopagrus arabicus)

در این مطالعه اثرات ویتامین e بر عملکرد تولیدمثلی ماهیان ماده‌ی شانک زرد باله عربی (acanthopagrus arabicus) مورد بررسی قرار گرفت. بدین منظور، به جیره پایه (50 درصد پروتئین خام، 18 درصد چربی خام) سطوح مختلف 0، 25، 50، 100، 250، 500 و 1000 میلی‌گرم ویتامین e در کیلوگرم غذا اضافه شد. بنابراین، 294 پیش مولد در 21 مخزن پلی اتیلن استوانه‌ای با حجم 1.5 مترمکعب (14 ماهی در هر مخزن) حاوی 1.2 متر مکعب آب دریا با شوری 40.2 گرم در لیتر، به نسبت جنسی 1:1 (نر: ماده) نگهداری شدند. ماهی‌ها دو بار در روز با جیره‌های آزمایشی، در طول مدت 135 روز تغذیه شدند. نتایج نشان داد که مکمل ویتامین e بر شاخص‌های رشد در مولدین ماده a. arabicus تاثیری نداشت. شاخص‌های تولیدمثلی شامل نرخ تخم ریزی، درصد لقاح، تخم گشایی و زنده‌مانی لارو در مولدین تغذیه شده با سطح 250 میلی گرم ویتامین e در کیلوگرم غذا افزایش یافت (0.05>p) درحالی‌که ناهنجاری جنین کاهش یافت. بر اساس یافته‌های مطالعه حاضر، افزودن 250 میلی‌گرم ویتامین e در کیلوگرم جیره غذایی برای بهبود عملکرد تولیدمثلی مانند درصد لقاح و تخم گشایی، نرخ تخم ریزی و زنده‌مانی لارو، در مولدهای ماده ماهی شانک زرد باله عربی توصیه می‌شود.

effect of dietary vitamin e on reproductive performance of female arabian yellowfin seabream (acanthopagrus arabicus)

introductionduring gonadal development and sexual maturation in fish, the metabolic rate in these tissues increases rapidly, generating a substantial number of free radicals (fernandez-palacios et al., 1998; izquierdo et al., 2001). research on various fish species has shown that incorporating high levels of vitamin e into fish diets reduces larval deformities, improves fecundity, enhances larval quality and development, and increases antioxidant resistance in eggs (nascimento et al., 2014; erdogan and arslan, 2021). conversely, a deficiency of vitamin e in the diet of female broodstock can lead to the development of immature gonads, reduced egg fertilization, lower hatching rates, and decreased larval survival (miller et al., 2012). during vitellogenesis in various fish species, vitamin e is transported by lipoproteins from visceral tissues to the ovaries (lie et al., 1993; hemre et al., 1994; tokuda et al., 2000; huang et al., 2019). for instance, in japanese flounder (paralichthys olivaceus), dietary supplementation of vitamin e at 1000 mg/kg has been found to enhance vitellogenesis, as well as the transfer and storage of this vitamin in the ovaries (tokuda et al., 2000). similarly, in turbot (scophthalmus maximus), the addition of vitamin e to the diet has been shown to stimulate the synthesis and secretion of reproductive hormones, specifically follicle-stimulating hormone (fsh) and luteinizing hormone (lh) (huang et al., 2019). acanthopagrus arabicus, commonly known as the yellowfin seabream, is a carnivorous species belonging to the family sparidae. it has been recognized as a promising candidate for the development of cage aquaculture along the southern coasts of iran (torfi mozanzadeh et al., 2021). however, there is limited information regarding the vitamin requirements of this species, particularly for broodstock. therefore, the present study was conducted to investigate the effects of vitamin e supplementation on the reproductive and physiological performance of a. arabicus.methodologyinitially, broodstock aged 1 to 2 years were captured by fishermen using hook fishing methods in the khormousi fishing area, beginning in mid-november. the broodstock of a. arabicus was maintained in two concrete tanks, each with a volume of 10 cubic meters, at a density of 10 fish per cubic meter. vitamin e was prepared at seven concentrations: 0, 25, 50, 100, 250, 500, and 1000 mg per kg of diet. the broodstocks were fed the experimental diets for 60 days before the onset of the breeding season and 75 days during the breeding season (from early march to mid-may). the experimental diets were provided to the broodstock twice daily (at 9:00 am and 3:00 pm) until satiety was achieved. spawning occurred naturally at the water temperature of 19°c. to collect the released eggs, the water inflow was shut off at 6:00 pm, and floating eggs were collected the following morning at 8:00 am using a funnel net (300 micrometers). the formulas referenced by safari et al. (2021) were then used to calculate spawning rates, fertilization rates, and other reproductive performance indicators. the kolmogorov-smirnov and levene tests were employed to assess the normality and homogeneity of variance in the data. a one-way analysis of variance (anova) followed by duncan’s multiple range test was conducted to evaluate the effects of dietary vitamin e on reproductive responses. additionally, orthogonal polynomial regression analysis was used to examine the relationship between reproductive factors and the dosage of vitamin e in the diet.resultsthe inclusion of varying vitamin e concentrations in the diet did not significantly affect the female broodstock’s final weight, condition factor, hepatosomatic index, viscerosomatic index, or gonadosomatic index. broodstock fed a diet containing 250 mg of vitamin e per kg exhibited the highest relative fecundity. the duration of spawning in broodstock fed diets containing 100 and 250 mg of vitamin e per kg was significantly longer compared to other treatments (p < 0.05). the highest fertilization rate was observed in fish fed the diet supplemented with 250 mg of vitamin e per kg, while the control group exhibited the lowest fertilization percentage. furthermore, the highest hatching rate and survival rate of three-day-old larvae were recorded in the group receiving 250 mg of vitamin e per kg. the lowest incidence of abnormalities during embryonic development occurred in the group fed a diet containing 50 mg of vitamin e per kg. the relationship between fertilization percentage, hatching rate, and larval survival indices with dietary vitamin e concentration followed a quadratic pattern.discussion and conclusionthe findings indicate that vitamin e supplementation did not significantly affect the growth indices of the broodstock. this lack of impact may be attributed to the allocation of energy and nutrients toward gonadal development, maturation, and gamete production, which likely reduced the energy available for somatic growth during the breeding season (safari et al., 2021). vitamin e plays a critical role in the synthesis of sex hormones in animals and has been shown to promote the accumulation of yolk granules in the ovaries as well as gonadal development in fish (zhang et al., 2007). in the present study, the inclusion of 250 mg of vitamin e in the diet of female a. arabicus resulted in enhanced fecundity, prolonged spawning duration, improved fertilization and hatching rates, reduced embryonic abnormalities, and increased larval survival. similarly, the addition of 200 mg of vitamin e to the diet of the swamp eel (monopterus albus) has been reported to promote gonadal development, increase spawning activity, and enhance hatching rates (zhang et al., 2007). furthermore, a study on a cichlid species (pseudotropheus socolofi) demonstrated that incorporating vitamin e at a concentration of 219.3 mg per kg significantly increased egg diameter, fecundity, spawning frequency, fertilization rates, hatching success, and larval survival (erdogan and arslan, 2019). studies indicate that vitamin e can regulate reproductive hormone levels and the expression of related genes during different developmental stages in fish (zhang et al., 2021). vitamin e is a fat-soluble compound essential for fish health and reproduction, acting as a structural element in cell membranes with antioxidant properties (griesh et al., 2024). the results of the present study suggest that supplementing the diet with 250 mg of vitamin e improves reproductive efficiency and larval survival rate in the female arabian yellowfin seabream (acanthopagrus arabicus).