en aquaculture aquaculture پژوهشي Orginal research papers <span style="font-size:11pt"><span style="line-height:102%"><span style="font-family:Calibri,sans-serif"><span lang="TR" style="font-size:12.0pt"><span style="line-height:102%"><span new="" roman="" style="font-family:" times=""><span style="color:black">In this study, trypsin was extracted from the viscera of yellowfin sea bream (<i>Acanthopagrus latus</i>) and used as an additive in</span></span></span></span><span lang="TR" style="font-size:12.0pt"><span style="line-height:102%"><span new="" roman="" style="font-family:" times=""><span style="color:black"> Sobaity sea bream,</span></span></span></span><span lang="TR" style="font-size:12.0pt"><span style="line-height:102%"><span new="" roman="" style="font-family:" times=""><span style="color:black"> <i>Sparidentex hasta</i>, larvae microdiet. The microdiet was supplemented with the extracted enzyme and its efficiency was evaluated in the growth performance of <i>S. hasta</i> larvae. There were five treatments containing zero (control), 1000, 1500, and 2000 IU/kg of the extracted trypsin with 500 IU/kg of a commercial diet of porcine trypsin. <i>S. hasta</i> larvae (mean initial weight of 0.021&plusmn;0.001 g) were fed with experimental diets for 28 days. Fifteen round polyethylene tanks (300 L, a water volume of 100 L) equipped with a water circulation system and an air stone were used for the treatments. The highest body weight gain (BWG), specific growth rate (SGR), daily growth, survival rate, and protein efficiency ratio (PER) were observed in the larvae fed the diet containing 2000 IU/kg trypsin (<i>p</i><0.05)</span></span></span></span><span dir="RTL" lang="AR-SA" style="font-size:12.0pt"><span style="line-height:102%"><span new="" roman="" style="font-family:" times=""><span style="color:black">.</span></span></span></span><span lang="TR" style="font-size:12.0pt"><span style="line-height:102%"><span new="" roman="" style="font-family:" times=""><span style="color:black"> In addition, the lowest and the highest values of the feed conversion ratio (FCR) vs daily feed intake and trypsin activity were significantly recorded in 2000 IU/kg trypsin and the control groups, respectively (<i>p</i><0.05). A positive correlation was observed between the increasing levels of trypsin in the microdiets and growth performance (<i>i.e. </i>BWG, SGR, daily growth rate, survival rate, and PER). Besides, the dietary addition of external trypsin reduced the values of FCR, daily feed intake, and trypsin activity in the larvae. Overall, trypsin at different doses, particularly at 2000 IU/kg, can significantly improve the performance and feed utilization of <i>S. hasta</i> larvae.</span></span></span></span></span></span></span> Sparidentex hasta, Weight gain, Protease enzyme, Microdiet, Correlation coefficient. 658 677 http://jifro.ir/browse.php?a_code=A-10-83-8&slc_lang=en&sid=1 F. Namjou faeze.namjou@yahoo.com 100319475328460049038 100319475328460049038 No Sari Agricultural Sciences and Natural Resources University S. Yeganeh skyeganeh@gmail.com 100319475328460049039 100319475328460049039 Yes Sari Agricultural Sciences and Natural Resources University R. Madani madanirasool@gmail.com 100319475328460049040 100319475328460049040 No Razi Vaccine and Serum Research Institute, Agricultural Research, Education and Extension Organization H. Ouraji hoseinoraji@yahoo.com 100319475328460049041 100319475328460049041 No Sari Agricultural Sciences and Natural Resources University