Evaluation of bioregulators use under various keeping conditions of barren cows Albina Aminova, Munir Sabitov, Albina Farkhutdinova, Idris Yumaguzin and Tatiana Sedykh E3S Web Conf., 282 (2021) 04011 Published online: 05 July 2021 DOI: 10.1051/e3sconf/202128204011