Measurements of body composition during late gestation and lactation in first and second parity sows and its relationship to piglet production and post-weaning reproductive performance

• We present the relationship among dam body condition traits, piglet performance and subsequent reproduction.
• Second parity dams have greater lean tissue loss during lactation and greater recovery post-weaning versus first parity dams.
• Dam body condition traits have no relationship with weaning to estrus interval.
• Dam body weight was positively associated with post-weaning ovulation rate.
• Litter size during lactation had negative effects on dam backfat thickness and loin eye area.

The objective of this study was to characterize multiple body condition traits in a white crossbred composite population of first- and second-parity sows and, determine if these traits relate to litter production and reproductive parameters. Differences between parity or time were determined using a mixed model and reported as LSM±SE. As expected, parity 2 dams were heavier (P<0.0001; 202.5±1.57 kg versus 174.1±1.35 kg) than parity 1 dams. Of interest however, parity 2 dams lost more (P=0.0340) loin eye area from late gestation to weaning (−4.1±0.78 cm2 versus −2.5±0.60 cm2) but had a greater (P=0.0026) recovery in loin eye area from weaning to post-weaning (2.8±0.76 cm2 versus 0.6±0.59 cm2) versus primiparous females. However the period between weaning measurements and post-weaning measurements tended (P=0.0978) to favor parity 1 dams (16.0±0.35 d) versus parity 2 dams (15.4±0.43 d). Parity 2 dams also had a greater (P≤0.05) ovulation rate following weaning than parity 1 dams. Regression analyses indicated body weight of dams at several time points had a positive (P≤0.05) relationship to ovulation rate (range 0.03±0.012 to 0.05±0.013 corpora lutea kg−1). Piglet ADG was positively (P≤0.05) associated with dam body weight (range 0.30±0.103 g kg−1 to 0.49±0.106 g kg−1) and dam backfat thickness (range 0.93±0.363 g mm−1 to 1.14±0.378 g mm−1) regardless of parity. Regression analyses indicated interactions (P≤0.05) between parity and backfat thickness at weaning (−0.11±0.023 piglets mm−1) and post-weaning backfat thickness (−0.12±0.025 piglets mm−1) were negatively associated with number of nursed piglets weaned among parity 1 dams. Furthermore, loin eye area at weaning (−0.06±0.024 piglets cm2 −1) and loss of loin eye area from late gestation to weaning (−0.05±0.020 piglets cm2 −1) were negatively (P≤0.05) associated with number of nursed piglets weaned but were not influenced by parity in regression analyses. In conclusion, these data provide knowledge on differences in body composition before and after the lactation period in young dams under similar conditions. Of interest, second parity dams appear to have greater lean tissue elasticity versus primiparous females. Future studies will further refine the relationship among body composition in primiparous females and subsequent impact on sow longevity.