Preweaning mortality in the pig. The prevalence of various causes of preweaning mortality and the importance of some contributory factors.

The relative importance of the various causes of preweaning mortality in the pig was determined from the results of autopsy and laboratory examinations on 718 animals. Conditions associated with parturition accounted for 25.1% of the losses, while physical factors (33.0%), starvation (12.8%) and septicaemia (10.9%) were the most common causes of death in piglets which were born alive. In contrast enteric diseases, viral infections, genetic conditions and various miscellaneous diseases played a relatively minor part. Some biological factors affected the prevalence of the various causes of death. Most losses from physical factors, starvation and septicaemia occurred during the first 4 days of life, while other infectious conditions were more common in older piglets. Large litters at birth had significantly more deaths associated with parturition and due to physical factors and starvation. Increased losses from physical factors occurred in the litters of gilts and sows of parity 5. The size of the enterprise and the use of farrowing crates combined to influence the extent of losses due to physical factors. A significantly higher mortality occurred in the large piggery in which crates were not used. The large units also had fewer deaths resulting from starvation.