Congenital malformations in pigs in a post mortem material.

Pigs which died during the preweaning period in 17 herds were examined post mortem over a 2-year period. In total 6,669 pigs, including 1,884 stillborn, from 2,936 litters died. The total number of pigs born constituted 29,886. Congenital malformations were registered in 410 pigs equalizing 1.4 per cent of the pigs born (Table I). The various malformations were analysed and related to a number of herd parameters. The herd to herd variation was 0.6--2.4 per cent, with a mean of 1.4 per cent. The incidence of affected litters was 11.8 per cent, showing a variation between the herds of 6.4 to 17.6 per cent. The frequency of malformed pigs was found to be higher in closed herds as compared to herds in which breeding stock was purchased (1.6 per cent versus 1.2 per cent). The relative importance of the various malformations is presented in Table II. The individual malformations are discussed, and it is concluded that the present investigation cannot contribute to a further genetical elucidation. Test matings with closely related animals, which is unrealizable in commercially run herds, are needed for that purpose. About 70 per cent of the recorded malformations appeared as phenotypic and could easily be recognized by a laid person. Malformations may therefore persist on a fairly low level as long as natural insemination is used. The present level of hereditary malformations may easily change with an increasing use of artificial insemination, and systematic monitoring of malformations becomes imperative in avoiding an unacceptable increase in the frequency of malformations. In processing collected data from sow/litter records and boar records, the data processing program applied in this study is supposed to be suitable.