A total of 66 litters were farrowed in a Yorkshire herd of pigs selected for porcine stress syndrome (PSS) susceptibility. These litters included all possible combinations of matings between stress-susceptible, stress-carrier, and stress-resistant animals. When the data were analyzed by within-litter chi-square analysis, the null hypothesis of recessive inheritance could not be rejected (P less than 0.05). In addition, when the data were analyzed across litters, the null hypothesis of autosomal recessive inheritance could not be rejected (P less than 0.05).

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PubMedDate not supplied

Prediction of susceptibility to the porcine stress syndrome.

An experiment designed to compare different predictors of porcine stress syndrome (PSS) was conducted. Animals were exposed to the anesthetic gas, halothane, and their reactions monitored to determine susceptibility or resistance to PSS. Two blood creatine phosphokinase (CPK) traits plus their logs10 were examined as predictors of PSS susceptibility. These were Sigma CPK, Antonik CPK, log Sigma CPK, and log Antonik CPK. The accuracy of these predictors varied from 87 percent to 91 percent in agreement with halothane-determined stress susceptibility. In addition, the relationship of PSS and blood types systems (AO,H) were studied. Two blood types, (+,-/-) and (-,+/+), were consistently stress susceptible while three blood types, (+,a/a), (+,a/c), and (+,c/-), were consistently stress resistant. However, one blood type (+,a/-) contained both stress-susceptible and stress-resistant individuals.

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PubMedDate not supplied

Evidence for multigene control of cryptorchidism in swine.

The mode of inheritance of cryptorchidism was investigated in Duroc swine. Matings of cryptorchid males with females whose full-sib brothers were cryptorchids were done. Sixteen of these litters were farrowed, and 54 males were born, of which 8 were cryptorchid. Two hypotheses were examined: first, that this trait is controlled by homozygosity of a recessive gene at a single locus; second, that it is controlled by homozygosity of recessive genes at two loci. The single-locus recessive hypothesis was rejected (P less than .01), but the two-locus model was not. Culling to reduce the incidence of cryptorchidism is discussed.

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