Analysis of frequency piglet mortality causes in nucleus herds

A large number of piglets horn per litter does not guarantee production success, it is only rearing a large litter that makes production profitable. The aim of the study was to evaluate the frequency of different piglet mortality causes during rearing to 21 days of age depending on litter size. A total of 266 975 litters of Polish Large White and Polish Landrace sows and their crossbreds were analysed for causes of piglet mortality to day 21 of life. Causes of mortality were classified into seven classes: crushing, low birth weight, diarrhoea, cachezia, genetic defects, sow agalactia and others. Mortality was observed in 121 149 litters (45.4%), hut it did not occur in 54.6% of litters. Litters with deaths were divided into three groups depending on the number of piglets born in the litter (<= 10, 11-14, >= 15 piglets) and the following parameters were calculated: number of live-born pigleftlitter, number of piglets on day 21 of life/litter and mortality rate/litter. The statistical analysis was based on the Kruskal-Wallis test. For group I and group III litter size at birth, piglet mortality rate to day 21 of life was 15.0 and 18.2%, respectively, which is higher by 2.7 and 5.9 percentage points (p.p.) than in group II. Piglet deaths were mainly due to low birth weight. A problem was also mortality due to genetic defects, which increased with an increasing litter size. Analysis of the results shows that particular attention should he given to eliminating reasons contributing to lower birth weight of piglets.