EN
The cortisol level was estimated, before and after slaughter, in the serum of 80-days-old rams of the kamieniecka sheep (K) and their crossbred (F₁) with rams of the Berrichon du Cher (KxBCH), Blackhead (KxCz) and Ile de France (KxIF) race. The cortisol level tested before the preslaughter movement was different in the studied genetic groups of lambs. The highest initial concentration of the hormone was found in lambs of KxIF (40.10 nmol/l) and K (39.51 nmol/1). After the preslaughter stress, concentration of the studied hormone increased in all the lamb groups. The lowest stress sensitivity was observed in the lambs of pure K race, which has the smallest increase of the cortisol level (1.46 times more than the initial one). In crossbred groups of lambs, the highest stress sensitivity was observed in KxBCH Iambs. They had 3.72 times greater increase of the studied hormone level. A slightly lower stress sensitivity occured in KxCz (3 times greater) and KxIF (1.8 times greater). There was no significant difference between the temperature, measured per rectum, before and after the transport of animals.