تعيين احتياجات غذايي ماهي آزاد درياي خزر با هدف آبزي پروري

Nutrient requirement in Salmo trutta caspius kessler (1870) for aquaculture purpose

آزمايش تعيين احتياجات غذايي ماهي آزاد درياي خزر با 6 تيمار و در 3 تكرار و به مدت 8 هفته در سالن تكثير و پرورش پژوهشكده اكولوژي درياي خزر در فرح آباد ساري در استان مازندران اجراء شد. تعداد 720 عدد بچه ماهي آزاد درياي خزر (Salmo trutta caspius Kessler1877) با ميانگين وزني 7 گرم در 18 ونيرو به طور تصادفي تقسيم گرديدند. شش جيره غذايي با استفاده از سه سطح پروتئين (45%، 50% و 55 %) و دو سطح انرژي (3/5 و 4 كيلوكالري در چارچوب يك طرح آزمايشي فاكتوريل (3×2) تهيه گرديد. غذادهي مطابق با درجه حرارت آب و اندازه ماهي كه معمولا از 1/5 تا 0/04 وزن بدن متغير بوده است، روزي سه بار (ساعات 8، 12 و 16) انجام شد. بررسي ها نشان داد كه غذاي حاوي 45% پروتئين بر برخي شاخص هاي رشد مانند ضريب تبديل غذايي و نسبت بازده پروتئين اثر معني داري مثبت داشته است (0/05>p) اما با افزايش انرژي از 3500 به 4000 كالري اثر معني داري بر شاخص هاي رشد ماهي ديده نمي شود (0/05

A sharp decline in natural population of Caspian brown trout lead to implementing of restocking program in Iran. Along the stock recovery program، the artificial production of this species has been attracted too much attention in recent years. The objective of the study is to assess the effects of protein and energy levels of diet on fish performance، growth efficiency of Caspian brown trout in order to develop a proper diet for production of this species. Six experimental diets were formulated by replacing casein as a pure protein source with fat as an energy source in the diets according to a 3×2 factorial design. The diet was assigned to 18 tanks with 50 fish each، with three replicated for each diet. The experiment was conducted for 8 weeks with Caspian brown trout with an initial body weight of around 7 g. Caspian brown trout demonstrated a better FCR and a larger SGR at lower protein levels (45 and 50%) in comparison to high protein level (55%; P<0.05). Protein efficiency ratio improved by a decrease in protein content of the diet (P<0.05)، but energy content of diets does not affect any growth related parameter such as FCR، SGR and PER (p>0.05). There was also no interaction between protein and energy levels in the growth related parameters، suggesting the effect of protein on the growth parameters in Caspian brown trout did not depend on energy levels of diet. In conclusion diet containing 50% protein can support the maximum growth. High dietary energy level of the diet dose in cooperate in protein sparing effect.