اثرات جايگزيني روغن ماهي جيره غذايي با سطوح مختلف روغن گياهي كانولا بر شاخص هاي رشد و بازماندگي بچه ماهي آزاد درياي خزر (Salmo trutta caspius)

Replacement of fish oil with canola vegetable oil-based diets on growth and survival rate of Caspian trout, Salmo caspius fry

بررسي ﺣﺎﺿﺮ ﺑﻪ ﻣﻨﻈﻮر ارزﯾﺎﺑﯽ ﺗﺄﺛﯿﺮ ﺟﺎﯾﮕﺰﯾﻨﯽ روﻏﻦ ﻣﺎﻫﯽ ﮐﯿﻠﮑﺎ ﺑﺎ ﺳﻄﻮح ﻣﺨﺘﻠﻒ روﻏﻦ ﮐﺎﻧﻮﻻ ﺑﺮ ﺷﺎﺧﺺﻫﺎي رﺷﺪ و ﺑﺎزﻣﺎﻧﺪﮔﯽ ﺑﭽﻪ ﻣﺎﻫﯽ آزاد درﯾﺎي ﺧﺰر )Salmo caspius( در ﻃﯽ ﯾﮏ دوره 60 روزه ﻃﺮاﺣﯽ و اﻧﺠﺎم ﺷﺪ. ﺗﻌﺪاد 180 ﻗﻄﻌﻪ ﺑﭽﻪ ﻣﺎﻫﯽ )0/23 ± 4/6 ﮔﺮم(با تراكم 15 قطعه در حوضچه هاي 300 ليتري توزيع و با 4 تيمار غذايي هر يك با سه تكرار شامل جيره هاي حاوي 100% روغن ماهي، 100% روغن كانولا، 50% روغن ماهي و 50% روغن كانولا، 70 درصد روغن ماهي و 30 درصد روغن كانولا (با سطوح پروتيين و چربي يكسان به ترتيب 43 و 14 درصد) تغذيه شدند. بيشترين ميزان ميانگين وزن (46/26 گرم)، طول نهايي (46/13 سانتيمتر) و ضريب رشد ويژه (97/2%) را ماهيان تغذيه شده با تيمار 50% روغن ماهي و 50% روغن كانولا به خود اختصاص دادند كه دارايﺑﺎ دﯾﮕﺮ ﺗﯿﻤﺎرﻫﺎ ﺑﻮدﻧﺪ )p≤0/05(. ﻫﻤﭽﻨﯿﻦ، ﭘﺎﯾﯿﻦﺗﺮﯾﻦ ﻣﻘﺪار ﺿﺮﯾﺐ ﺗﺒﺪﯾﻞ ﻏﺬاﯾﯽ )1/41( و ﺑﺎﻻﺗﺮﯾﻦ ﻣﯿﺰان ﻓﺎﮐﺘﻮر وﺿﻌﯿﺖ )0/08 ± 1/17( در ﺗﯿﻤﺎر 3 ﻣﺸﺎﻫﺪه ﺷﺪ. ﺑﺎﻻﺗﺮﯾﻦ ﻧﺮخ ﮐﺎراﯾﯽ ﭘﺮوﺗﺌﯿﻦ ﻣﺮﺑﻮﻃﻪ ﺑﻪ ﺗﯿﻤﺎر 4 ﺑﻮد ﮐﻪ اﺧﺘﻼف ﻣﻌﻨﯽداري را ﺑﺎ دﯾﮕﺮ ﺗﯿﻤﺎرﻫﺎ ﻧﺸﺎن داد )p≤0/05(. ﻣﯿﺰان درﺻﺪ ﺑﺎزﻣﺎﻧﺪﮔﯽ در ﺑﯿﻦ ﺗﻤﺎﻣﯽ ﺗﯿﻤﺎرﻫﺎ 100% ﺑﻮد. ﺑﺮ اﺳﺎس ﻧﺘﺎﯾﺞ ﺣﺎﺻﻞ ﺷﺪه، ﺟﺎﯾﮕﺰﯾﻨﯽ ﺑﺨﺸﯽ از روﻏﻦ ﮐﺎﻧﻮﻻ ﺑﺎ روﻏﻦ ﻣﺎﻫﯽ )50% روﻏﻦ ﻣﺎﻫﯽ ﺑﺎ 50% روﻏﻦ ﮐﺎﻧﻮﻻ( در ﺟﯿﺮه ﻧﻪ ﺗﻨﻬﺎ ﺗﺄﺛﯿﺮ ﻣﻨﻔﯽ ﺑﺮ ﺷﺎﺧﺺﻫﺎي رﺷﺪ و ﺑﺎزﻣﺎﻧﺪﮔﯽ ﺑﭽﻪ ﻣﺎﻫﯽ آزاد درﯾﺎي ﺧﺰر ﻧﺪارد، ﺑﻠﮑﻪ ﺑﻬﺒﻮد اﯾﻦ ﺷﺎﺧﺺﻫﺎ را ﻧﯿﺰ ﺑﻪﻫﻤﺮاه ﺧﻮاﻫﺪ داﺷﺖ و ﺑﺎ ﮐﺎﻫﺶ ﻃﻮل دوره ﭘﺮورش، ﻣﻮﺟﺐ ﮐﺎﻫﺶ ﻫﺰﯾﻨﻪﻫﺎ ﻣﯽﺷﻮد

This study was conducted to evaluate the effects of different levels of canola oil on growth performance and survival rate of Caspian trout (Salmo caspius) fry during replacement with canola oil over a period of 60 days. 180 pieces of fish fry (4.6 ± 0.23 g in weight) with a density of 15 individuals were placed in 300-liter fiberglass tanks. Four treatments each with 3 replicates were fed with diets including 100% fish oil (T1), 100% canola oil (T2), 50% fish oil and 50% canola oil (T3), 70% fish oil and 30% canola oil (T4) with the same protein and fat levels of 43% and 14%, respectively. The results showed that the highest weight (26.46 g), final length (13.46 cm) and specific growth rate (2.97%/day) belonged to T3 exhibiting a significant difference with other treatments (p≤0.05). Moreover, the lowest value of feed conversion ratio (1.41) and the highest amount of condition factor (1.17 ± 0.08) were also found in T3. However, these differences were not statistically significant (p>0.05). The highest protein efficiency coefficient of 2.37 was found in T4, exhibiting a significant difference with other treatments (p≤0.05). The survival rate among all treatments was 100% (with no mortality). Based on the results, it can be concluded that the partialy replacement of fish oil with canola oil (50% fish oil with 50% canola oil) in the diet of Caspian trout not only has no negative impact on growth indices and survival rate, but also can enhance these indices and decrease costs by reducing the length of the culture period.