K. Stankov Department of Management, Faculty of Economics, Trakia University, 6000 Stara Zagora, Bulgaria (Manuscript received 22 August 2020; accepted for publication 16 October 2020) Abstract. A study was conducted on the effect of clinical mastitis at Holstein-Friesian cows on the

H. Lukanov1*, I. Pavlova2 1Department of Animal Science – monogastric and other animals, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of General livestock breeding, Faculty of Veterinary medicine, Trakia University, 6000 Stara Zagora, Bulgar