193. Increasing Organic Trace Mineral Supplementation During Late Gestation and Lactation Influences Sow Iron Status and Litter Weaning Performance in Prolific Sows.

Abstract The objective of this study was to evaluate the effects of increasing dietary TM supplementation during late gestation and lactation on reproductive performance and sow and progeny iron status. Forty-five sows (parity 0–4) at 70 ± 2 d of gestation were alloted by parity, body weight (BW), and blood hemoglobin (Hb) and assigned to one of four dietary treatments: 1) control with no supplemental TM (CON), 2) TM supplied at NRC (2012) estimated requirements (NRC), 3) 2 × NRC TM levels (2×NRC), or 4) 3 × NRC TM levels (3×NRC). Trace minerals were supplied in organic forms, with zinc, iron, copper, and manganese provided as polysaccharide-complexed sources. Selenium inclusion was constrained to remain within established regulatory limits across all treatments. Sow blood samples and BWs were collected on d 70, 90, and 110 of gestation and on d 2 of lactation and at weaning (lactation d 20 ± 3). Piglets were weighed and tested for Hb at birth (N = 732) and weaning (N = 639). Blood samples were collected from two piglets per litter (n = 140) at 40–48 h after birth and again at weaning. Data was analyzed using PROC MIXED (SAS 9.4) with dietary treatment as a fixed effect and sow as a random effect, and orthogonal polynomial contrasts were used to evaluate quadratic responses to increasing TM supplementation. Day 90 gestation sow Hb responded quadratically to increasing trace mineral supplementation (CON: 11.6 g/dL; NRC: 11.7 g/dL; 2xNRC: 12.8 g/dL; 3xNRC: 12.2 g/dL, quadratic: P = 0.076), with the fitted model estimating maximal Hb concentration at 2.4 × NRC recommendations. Predicted peak Hb concentration at the estimated optimum was 12.4 g/dL. Reproductive traits, including total born, liveborn, stillborn percentage, and farrowing duration, as well as sow BW, were not affected by treatment. Number of pigs weaned increased and then decreased (quadratic, P = 0.014) as TM supplementation increased (CON: 12.91; NRC: 14.72; 2xNRC: 15.00; 3xNRC: 14.17). Piglet wean weights tended to be greater in the 2xNRC (6.34kg) than the other treatment groups (CON: 5.71kg; NRC: 5.59 kg; 3xNRC: 5.61kg; P = 0.091). Total litter wean weight exhibited a quadratic response to increasing TM supplementation (CON: 76.78 kg ; NRC: 80.31kg; 2xNRC: 91.15kg; 3xNRC: 79.56kg, quadratic: P = 0.072), with the fitted model estimating maximal litter wean weight at approximately 1.75 × NRC recommendations. The predicted litter wean weight at the estimated optimum was 86.9 kg. In conclusion, maternal Hb concentration and litter wean weight were optimized at different organic TM inclusion levels, suggesting that supplementation at 1.75 to 2.0 × NRC TM estimated requirements supports maternal iron status without compromising litter growth performance.