fa Assisted reproductive technologies (ART) Assisted reproductive technologies (ART) كاربردي Applicable <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Background:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> The aim of this study was to compare the quality of bull sperm produced in 0.5 and 0.25 ml semen straws before and after freezing.</span></span></span></span></span></span><br /> <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Methods:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> In this experimental study, semen samples were collected from 12 dual purpose Simmental (Fleckvieh) bull kept at Iran Simmental Cattle Breeding Center during a two-month period. Each ejaculate was divided into two equal portions. Then, the formulation and freezing processes were performed separately for each type of straw. Sperm qualitative characteristics, antioxidant and oxidant levels of frozen semen produced in bulls&#39; 0.5 and 0.25 were compared.<br /> <b>Results:</b> The results showed that all sperm quality parameters in 0.25 ml straws were better than 0.5 ml before and after freezing. Catalase (CAT) activity was higher in 0.5 ml straws than 0.25 one, but it was not statistically significant. Malondialdehyde (MDA) levels were lower in 0.5 ml straws than 0.25 ml straws, but the differences were not statically significant. Moreover, no remarkable difference was observed in the activity of superoxide dismutase (SOD) activity enzyme.</span></span></span></span></span></span><br /> <span style="font-size:11pt"><span style="line-height:14.0pt"><span style="text-autospace:none"><span calibri="" style="font-family:"><b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times="">Conclusion:</span></span></b><span style="font-size:10.0pt"><span new="" roman="" style="font-family:" times=""> Based on the findings of the present study and with the aim of reducing the production costs, it is recommended that bull sperm production centers and herdsman inseminators use 0.25 ml straws for semen freezing and cattle artificial insemination.</span></span></span></span></span></span> Antioxidants, Cattle, Oxidants, Semen, Semen Preservation, Spermatozoa 8 16 http://caspjrm.ir/browse.php?a_code=A-12-101-4&slc_lang=fa&sid=1 Amir Khaki 10031947532846002289 10031947532846002289 No Atefeh Araghi a.araghi@ausmt.ac.ir 10031947532846002290 10031947532846002290 Yes Department of Clinical Sciences, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Mazandaran, Iran Alireza Ghasemi 10031947532846002291 10031947532846002291 No Samaneh Rezaei-larijani 10031947532846002292 10031947532846002292 No