TY JOUR TI ANALYSIS OF MASSAGE DEVICE OPERATION ON THE BASIS OF PNEUMATIC ELEMENTS FOR HEIFER UDDER KW heifers KW udder KW massaging device KW workable and operational diagram KW combined massage KW vacuum KW pulse controller JO Bulletin Samara State Agricultural Academy AU Kurochkin, A.A. AU Frolov, D.I. PY 2021 IS 6 PB Samara State Agrarian University