Effect of genetic factors on the criteria of stress in fighting bulls.

The effect of 40 genetic markers (blood groups and biochemical polymorphisms) on 5 haematological parameters (haematocrit, haemoglobin concentration, red blood cells count, white blood cells count and differential leucocyte count) was studied in 179 fighting bulls to investigate whether genetic background was related to stress endurance. Analysis of data was carried out by Harvey's methods (1977). Environmental factors (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 carbonic anhydrase (Ca) and transferrin (Tf) genotypes showed a significant effect on all studied parameters. Our results show that fighting bulls with the H antigen and those without A, G2 and G3 antigens had lower haematocrit and haemoglobin concentrations than the average population, whereas the fighting bulls with CaS/CaS and TfA/TfE genotypes showed a higher reversal of the leukocyte differential count than the average population. These results may suggest a better adaptation to resistance to stress in animals displaying H antigens and CaS/CaS, TfA/TfE genotypes and in those without A, G2 and G3 antigens.