Conception Rate from First AI in Cows Submitted to Three Different Synhronization Protocols: A Single PGF 2α Injection - Atanasov Branko, Trbogazov Zvonko , Ilievska Ksenija , Nikolovski Martin, Petkov Vladimir , Dovenska Monika , Adamov Nikola , Stojanov Boris , Dovenski Toni (Faculty of Veterinary Medicine - Skopje, 2016)