[The relationship between hereditary characteristics in the blood (Phi-PO2-Pgd) and susceptibility to stress in...

Deaths during transport and the incidence of a poor quality of the meat in pigs were the most important reasons for studying the stress-syndrome (MHS) during the past twenty years. MHS is controlled by an autosomal Hal locus with two alleles N and n. Only pigs of genotype nn are sensitive to halothane and susceptible to stress. As a standard test for use in practice, the halothane test was developed in the Netherlands in 1974 and only this test is used to detect MHS. Heterozygotes can not be detected using this test. Since 1986, additional blood typing was carried out for the systems Phi, Po2 en Pgd in litters including at least one halothane-positive reactor. Blood typing was carried out in 533 pigs of four different lines of breeding company Cofok in Oosterhout and was found to be very successful (using the linkage groups) in identifying the heterozygotes. In 15.5 per cent of the offspring, it could not be stated whether the genotype was HalNN or HalNn. This was due to the fact that in these Nn x Nn matings the two haplotypes of one or both parents were identical. In this population, the haplotype PhiB-Po2S-PgdB was strongly (72-89 per cent) linked to the Haln-allele.