The influence of the weaning-to-breeding interval on ovulation rate in parity-two sows
Anne E. Deckert, DVM, MS; Catherine E. Dewey DVM, MSc, PhD; J. Joe Ford, PhD; Barbara E. Straw, DVM, PhD
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Objective: To determine whether changes in litter size with respect to the postweaning interval were associated with changes in ovulation rate.
Methods: Three hundred and seventy-six white crossbred sows of four different parities were bred if they showed estrus by day 14 postweaning. They were slaughtered at 21-33 days of gestation and the ovaries dissected to determine the number of corpora lutea. The number of corpora lutea were assumed to equal the ovulation rate.
Results: Average ovulation rate for all sows in the study was 14.58 +/- 0.32 ova and for the parity-two sows was 14.0 +/- 0.23 ova. The mean weaning-to-breeding interval for the parity-two sows was 5.87 +/- 0.14 days. Ovulation rate in the parity-two sows increased by 0.25 +/- 0.09 ova as the number of piglets weaned in the sow's previous parity increased by one piglet (P <.05). The parity-two sow's population line and the season she was weaned were also associated with ovulation rate (P <.001). Compared with sows with weaning-to-breeding intervals of 4-5 days, ovulation rate decreased by 1.04 +/- 0.39 ova for parity-two sows with weaning-to-breeding intervals of 6 days, increased by 3.08 +/- 0.96 for sows returning to estrus 9 days postweaning, and decreased by 2.62 +/- 1.13 for sows returning 10-12 days postweaning (P < .05).
Implications: Ovulation rate is highly associated with with weaning-to-breeding intervals.
Keywords: sows, postweaning interval, ovulation, season, lactational weight loss
Cite as: Deckert AE, Dewey CE, Ford JJ, et al. The influence of the weaning-to-breeding interval on ovulation rate in parity-two sows. J Swine Health Prod 1997;5(3):89-93.
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