List of Articles Open and Closed breeding system Open Access Article Abstract Page Full-Text 1 - Comparison of serum beta-carotene and vitamin A levels in sheep of Khalkhal region in open and closed breeding system esmaiil Amani Firoozabad Ali Hassanpour amir ganj khanloo Abdollah Dolatabadi 10.30495/jvcp.2020.515131.1261