Effects of Protein Supplementation During Early Gestation on Sow Reproductive Performance, Sow Metabolism, and Offspring Pre-weaning Outcomes

Abstract Objective This study aimed to investigate the dose-response effects of increased protein supplementation during early gestation on sow reproductive performance, sow metabolism, and offspring pre-weaning performance. Methods Seventy-seven mixed-parity sows (genetic TN70) were blocked by parity and body weight and assigned to one of five dietary treatments, consisting of graded levels of protein supplementation expressed as daily intake of standardized ileal digestible (SID) lysine (Lys). The treatments provided, on average, 10, 14, 17, 21, or 25 g/day SID Lys from at least one day before breeding to day 35 post-breeding. All sows received 2.2 kg/day of a base gestation diet formulated to meet NRC 2012 requirements, which supplied 10 g/day SID Lys. Additional soy protein isolate (SPI) was top-dressed daily to reach the target SID Lys levels, maintaining essential amino acid-to-Lys ratios at or above NRC 2012 recommendations. Sow body weight (BW) was measured at 11 time points throughout gestation, and postprandial blood samples were collected on days 5 and 35 post-breeding for metabolomics analyses. Litter characteristics at farrowing and offspring performance during lactation were also evaluated. A total of sixty-one sows farrowed and were included in the statistical analyses. Reproductive and performance data were analyzed with generalized linear models, while data from blood metabolites were analyzed with linear mixed effects models. Orthogonal polynomial contrasts of second order were applied to assess the treatment response. Results Sow BW change during gestation showed a quadratic response (p = 0.036), with the greatest gain observed in sows fed 17 g/day SID Lys. The number of pigs born alive tended to follow a quadratic response (p = 0.090). Similarly, the number of stillborn piglets and overall litter perinatal mortality exhibited quadratic patterns (p = 0.006 and p = 0.047, respectively), with the lowest incidence at 17 g/day SID Lys. The serum ratio of reduced to oxidized glutathione (GSH:GSSG) was lower on day 5 than on day 35 post-breeding (p 0.002) and showed a quadratic response to treatment (p = 0.026); sows fed 17 g/d SID Lys were the only group with a ratio 1 on day 35. Blood urea nitrogen (BUN) concentrations were higher on day 5 than on day 35 post-breeding (p 0.001), increased linearly with dietary protein level (p 0.001), and showed a significant day × treatment interaction (p 0.001). No effect of treatment was observed on the performance of the offspring during lactation. Conclusion Increasing protein supplementation during early gestation affected maternal weight gain, oxidative status, incidence of stillbirths, and litter perinatal mortality with an apparent optimum around 17 g/day SID Lys.