Question:  query regarding  some conception 
Answer: told  him to provide good nutrition to the dam [ sow] ,to get best result /  ovarian cyst [ multiple cyst ] , overian  agenesis  may be a cause of infertility & hormonal imbalance , obstruction in the fallopian tube , alteration of ph in the uterus , pus formation , matritis bacterial , viral , ricketsial , clamydial infection may also be a cause of infertility , proper corrective measure should be taken,   may be the cause of infertility /if , more then 2 nos of sow was mated  with a single boar within 2-4 days ,then the conception may not occur due to decrease sperm , a gap should be maintained to get optimum result