اثرات دفعات غذادهی بر شاخص های تولید در قزل‌آلای رنگین‌کمان (onchorhynchus mykiss)

این مطالعه با هدف تعیین اثر دفعات غذادهی بر شاخص‌های رشد، تغذیه و بازماندگی در قزل آلای رنگین کمان (onchorhynchus mykiss) طراحی گردید. در این آزمایش تعداد 216 قطعه ماهی قزل‌آلای رنگین‌کمان با میانگین وزنی 0.11± 38 گرم در 18 تانک فایبرگلاس 300 لیتری بصورت کاملاً تصادفی توزیع شدند. 3 تیمار آزمایشی شامل دفعات مختلف غذادهی 1، 3 و 5 نوبت در روز (بترتیب تیمار 1، 2 و 3) با 6 تکرار و براساس 5 درصد وزن توده زنده به مدت 90 روز تغذیه گردیدند. در پایان دوره آزمایشی، اختلاف معنی‌داری در تمامی شاخص‌های رشد مشاهده شد. در همه این شاخص‌ها تیمار 2 بر تیمار 3 برتری داشت و اختلاف معنی داری بین تیمار 2 و 1 مشاهده شد. نتایج حاصل از اندازه‌گیری ضریب کارایی غذایی در این مطالعه نشان داد که کارایی غذایی در تیمار 1 دارای کم‌ترین مقدار بوده و با تیمار 2 و 3 دارای اختلاف معناداری می‌باشد (0.05>p). بیش‌ترین مقدار از این شاخص برای تیمار 2 مشاهده شد درحالیکه با تیمار 3، اختلاف معناداری نداشت (0.05

effects of feeding frequency on production indices in rainbow trout (onchorhynchus mykiss)

abstractthis study aimed to determine the effect of feeding frequency on growth, nutrition, and survival indices in rainbow trout (oncorhynchus mykiss). in this experiment, 216 rainbow trout with an average weight of 38 ± 0.11 g were distributed in 18 (300 liter fiberglass) tanks complete randomly. three experimental treatments including different feeding times 1, 3, and 5 times a day (treatments 1, 2, and 3, respectively), were fed with 6 replications and based on 5% of biomass weight for 90 days. at the end of the experimental period, a significant difference was observed in all growth indices. in all these indicators, treatment 2 was superior to treatment 3. a significant difference was observed between treatments 2 and 1. the results of measuring feed efficiency ratio in this study showed that feed efficiency in treatment 1 has the lowest value and has a significant difference with treatments 2 and 3 (p<0.05). the highest value of this index was observed for treatment 2, while there was no significant difference with treatment 3. the lowest survival rate was observed in treatment 1, and the highest value was observed in treatment 2. the economic efficiency ratio showed that thrice a day in treatment 2 the most cost effective feeding times. so the maximum feed cost was observed in treatment 1, and the minimum amount was observed in treatment 2. the results showed the frequency of feeding 3 times a day in terms of production in rainbow trout.  introductionin aquaculture, feeding frequency analysis is crucial as feeding at the appropriate frequency can improve growth performance and feed consumption efficiency while reducing farm feeding costs. in other words, the feeding frequency can influence digestion and absorption of the diet, which leads to synchronization of diet efficiency with appetite. enhancing feed efficiency can play a significant role in helping the aquaculture industry achieve sustainability and reduce production costs.  materials and methods216 rainbow trout, with an average weight of 38±0.11 g, were transported to the experimental site (300 litre fiberglass tanks). the fish were reared in three different treatments, each with six replications containing 12 fish, for 90 days after acclimation to laboratory conditions for 14 days. three different feeding scheduleswere designed for the experimental treatments: treatment 1: once daily at 9:00; treatment 2: three timesdaily at 9:00, 13:00, and 17:00; and treatment 3: five times daily at 9:00, 13:00, 15:00, 17:00, and 19:00. the fish were fed with commercial extruded diet (faradaneh company, iran) at 5% of body weight. the variables analyzed in this study were: percentage weight gain, daily weight gain, specific growth rate, survival rate, condition factor, visceral somatic index, feed efficiency ratio, survival rate, and economy efficiency ratio. resultsthe results of the growth indices measured in rainbow trout at the end of the experimental period indicated a significant difference in all growth indices. in all these indicators, treatment 2 outperformed treatment 3. the highest and lowest percentage weight gain and specific growth rate were observed in treatments 2 and 1, respectively. the study's results on feed efficiency ratio indicate that treatment 1 had the lowest feed efficiency and a significant difference from treatments 2 and 3. treatment 1 also had the lowest survival rate percent at 91.40 ± 5.89, while treatment 2 had the highest at 99.00 ± 1.10. feeding the fish three times a day in treatment two was found to be the most cost effective, with treatment 1 showing the highest feed cost. discussion and conclusion the study demonstrates that increased feeding frequency has improved some growth and feed indicators as measured. in treatment 2, the maximum level of these indicators was observed when feeding occurred three times a day. feeding three times a day is more cost effective than feeding once or five times a day, according to the results of the economic efficiency ratio. thus, the increase in feed efficiency observed in treatment 2 in the study could be attributed to the appropriate frequency and the suitable amount of diet consumed each time. feeding rainbow trout three times a day can be recommended as the practical feeding frequency considering the management conditions of this experiment.