The relationships between 41 genetic markers (blood groups and biochem
ical polymorphisms), 3 environmental factors (season, management befor
e the Lidia (''encierro''), punishment suffered), body constitution, a
nd pedigree on the one hand, and the activity of muscular enzymes in s
erum, creatine kinase (CK), lactate dehydrogenase (LDH), asparate tran
saminase (AST)) on the other, were analyzed in 179 fighting bulls. The
C system of cattle blood groups and the ''encierro'' were significant
ly related to the activity of the muscular enzymes of the studied anim
als. The fighting bulls with the W1 and C1 antigens had a higher CK an
d LDH activity respectively, whereas the fighting bulls with the X1 an
tigen as well as those that participate in the ''encierro'' had a lowe
r AST activity. This results could suggest a lesser degree of muscular
injury during the Lidia in animals with X1 antigen, in those that par
ticipate in the ''encierro'', and in those without W1 and C1 antigens.