Comparisons were made to better understand the fundamental differences between mature multiparous and growing first parity Cotswold sows. Equalization of metabolic demand in nine first parity and eight fifth parity sows was made by standardizing litter sizes by day 3 postpartum (pp) to 10 and 12 piglets for first and fifth parity sows, respectively. Weaning of piglets was at 14 days pp. Sows were fitted with venous cannulae at approximately day 107 of gestation to facilitate frequent blood sampling. Blood was collected at 20-minute intervals for 8 hours on days 110 of gestation (g) and 3 pp, for 10 hours on days 13 pp and 4 postweaning (pw), for 5 hours on the day prior to estrus and at estrus, for 3 hours on day 2 postbreeding (pb) and for 5 hours on days 5, 10 and 15 pb. In addition, single daily blood samples were collected from day 10 pp to 14 days pb and on the day prior to slaughter at 27-35 days pb following mating at the first postweaning estrus. Reproductive tracts were recovered after slaughter and ovulation rate and embryo mortality were determined at this time. (Abstract shortened by UMI.)
