EFFECT OF GENETIC-FACTORS ON THE CRITERIA OF STRESS IN FIGHTING BULLS

The effect of 40 genetic markers (blood groups and biochemical polymor phisms) on 5 haematological parameters (haematocrit, haemoglobin conce ntration, red blood cells count, white blood cells count and different ial leucocyte count) was studied in 179 fighting bulls to investigate whether genetic background was related to stress endurance. Analysis o f data was carried out by Harvey's methods (1977). Environmental facto rs (season, management before the bullfight, ''encierro'' and suffered punishment), body constitution and pedigree were also included in the analysis. The A, B and S system of cattle blood groups, erythrocyte c arbonic anhydrase (Ca) and transferrin (Tf) genotypes showed a signifi cant effect on all studied parameters. Our results show that fighting bulls with the H antigen and those without A, G(2) and G(3) antigens h ad lower haematocrit and haemoglobin concentrations than the average p opulation, whereas the fighting bulls with Ca-s/Ca-s and Tf(A)/Tf(E) g enotypes showed a higher reversal of the leukocyte differential count than the average population. These results may suggest a better adapta tion to resistance to stress in animals displaying H antigens and Ca-s /Ca-s, Tf(A)/Tf(E) genotypes and in those without A, G(2) and G(3) ant igens.