An analysis of survey data by size of the breeding herd for the reproductive management practices of North American sow farms

Robert Victor Knox, Sandra Luisa Rodriguez-Zas, N. L. Sloter, K. A. McNamara, T. J. Gall, D. G. Levis, T. J. Safranski, W. L. Singleton

Research output: Contribution to journalArticlepeer-review


A survey was performed to assess whether reproductive management differed among small-sized (Sm, < 500 sows), medium-sized (M, 501 to 2,000 sows), and large-sized (Lg, 2,001 to 8,000 sows) farms (n = 113). Farms with 501 to 4000 sows/barn were most frequent with sows kept in stalls on 90% of farms. More Lg farms (P < 0.05) functioned as breed to wean and more Sm and M as farrow to finish. More Sm and Lg farms weaned at >21 d, whereas M farms were more likely to wean at 18 to 21 d (P < 0.05). More Lg farms had farrowing rates above 89% than Sm and M farms (P < 0.05), and culling rates above 40% were more frequent on M and Lg farms than on S. On M and Lg farms, sows were bred in larger batches, using lower person to sow ratios, and with more people required than on Sm farms (P < 0.05). More (P < 0.05) M and Lg farms spent time moving sows and on records, but hours devoted to estrous detection, breeding, and other tasks did not differ among farms (P > 0.10). More M and Lg farms used more boars for estrus detection, rotated boars, and controlled boar movement than Sm farms (P < 0.05). Farm size also influenced semen sourcing, number of doses received, and frequency of semen delivery (P < 0.05). More M and Lg farms performed AI in the presence of a boar, left the AI rod in after AI, checked for returns, and diagnosed pregnancy than Sm farms (P < 0.05). Start of boar exposure after weaning began on 69% of farms within 2 d, occurring most often in the AM, but with exposure times varying from 1 to 5 min/sow. Semen was thermally protected for 50% of farms receiving shipments, and semen storage was consistent among farms. For AI, service occurred within minutes to hours after detection of estrus on 61% of farms. During AI, procedures such as back-pressure were required, whereas techniques such as hands-free AI were prohibited on most farms. Sow movement was allowed only once at 4 wk after breeding on 50% of farms, and pregnancy diagnosis occurred at 3 to 5 wk on 78% of farms. Most sows were allowed ≥1 chance for breeding after conception failure before culling. Incidence of fail to farrow was <5% and litter size was 10 to 13 pigs on >82% of farms. Summer infertility was observed on 69% of farms with estrus and pregnancy failures the leading causes. Over 70% of farms reported a technician effect on fertility. These results suggest that reproductive management of farms in key areas related to weaning, breeding, gestation, and labor use could be a source of variation in reproductive performance.

Original languageEnglish (US)
Pages (from-to)433-445
Number of pages13
JournalJournal of animal science
Issue number1
StatePublished - Jan 1 2013


  • Artificial insemination
  • Breeding herd
  • Fertility
  • Reproduction
  • Swine
  • United States of America

ASJC Scopus subject areas

  • Food Science
  • Medicine(all)
  • Animal Science and Zoology
  • Genetics


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