Seasonal infertility in large pig production units in an Eastern-European climate.
OBJECTIVE
To demonstrate the occurrence of seasonal infertility of sows in large production units in Eastern Europe.


METHODS
Weaners in this trial originated from a 1000 sow Croatian herd that weaned piglets at 14 or 28 days of age. The production records of 15 indoor (795 to 1849 sows per herd) pig farms with identical feeding, similar genetics and health status, were evaluated. The reproductive performance of sows when the average daily (9 am to 4 pm) temperature was more than 35 degrees C, was compared with the weeks when it was lower than 30 degrees C.


RESULTS
During periods of high temperature (> 35 degrees C) sows had significantly (P < or = 0.05) longer weaning to service intervals and more regular returns to service (P < or = 0.05) compared to weeks of less than 30 degrees C daily temperature in the same summer season. Irregular returns to service were low and showed no significant differences during the same time periods. Farrowing rates and total litter sizes were lower (P < or = 0.05) for periods of higher than 35 degrees C daily temperature compared to weeks of less than 30 degrees C daily temperature in the same summer season.


CONCLUSIONS
When daily temperatures are higher than 35 degrees C, reproductive performance is likely to be depressed in large pig production units.
Bilkei, Swine Ethology Studio, Raubbühlstrasse 4, CH-8600 Dübendorf, Switzerland.
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D000818:Animals; D002980:Climate; D005260:Female; D018882:Heat Stress Disorders / Q000209:etiology / Q000662:veterinary*; D006358:Hot Temperature / Q000009:adverse effects; D007247:Infertility, Female / Q000209:etiology / Q000662:veterinary*; D007315:Insemination, Artificial / Q000662:veterinary*; D011247:Pregnancy; D012098:Reproduction; D012621:Seasons; D013552:Swine; D013553:Swine Diseases / Q000209:etiology*; D013557:Switzerland / Q000453:epidemiology