Two research was conducted to evaluate and to classify the occurrence of the preweaning losses (based on the postmortem findings) of piglets in an intense swine production system, at the west of São Paulo State during the year 2000. Among total piglets born alive. 7.19 % died during the first 24 suckling days, but most of them (5.63 %) died on the 1st week of life all over the year. The most important causes of losses were overlaying (2.61 %), weakness (1.45 %), diarrhea syndrome (1.10 %), and genetic defects (0.56 %), occurring mainly on the 1st week of life. Stillbirth rate, in relation to total born, was 5.96 %. Evidences indicated higher number of overlaying during the hottest months of the year, caused probably by the longer staying out of the piglet's pen. It was suggested some control measures to reduce the piglets mortality in order to maximize the productive efficiency of the system.
Mortality; Piglets; Preweaning; Swine
