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Ben Williams

Knowledge Transfer Senior Manager

AHDB Pork Knowledge Exchange


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Seasonal infertility in UK pig production

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Research partners: University of Leeds

Sponsors: AHDB Pork

Duration: 2009–2011 

Aims and objectives

To investigate previously unidentified relationships between meteorological conditions and pig reproductive performance during periods of seasonal infertility in the UK. 


  • Reduced farrowing rates were the major manifestation of seasonality in sows
  • High temperatures and long days were associated with poor performance
  • Seasonal effects on litter size were less apparent when assessed at herd level
  • Individual sows were found to be more or less susceptible to reductions from summer services, suggesting a genetic predisposition to seasonal infertility
  • Sow skin temperatures and respiration rates increased with external temperature humidity indices; these increases occurred at a lower threshold following cold conditions
  • It appears that UK sows become acclimatised to cold weather and are therefore more susceptible to heat stress when it becomes warmer
  • Boar semen quality was reduced over the summer and early autumn months, with a higher proportion of abnormalities and lower sperm concentration
  • Individual boar and management parameters had a larger effect on semen quality than meteorological conditions. 

Further information