PS5-15. Effect of Late-gestation Micronutrient Supplementation on Sow Hemoglobin Concentration and Farrowing Outcomes

Abstract Anemia during late gestation may reduce uterine contractility and oxygen delivery, increasing the risk of stillbirths and compromised farrowing performance. The objective of this study was to evaluate the effects of supplemental micronutrients on hemoglobin (Hb) concentrations and sow reproductive performance under commercial conditions. A total of 239 individually housed sows were balanced by parity (P0-P10) and body condition score (BCS, 1-5) and allocated on d 90 of gestation to 3 top-dressed treatments: Control (corn carrier), Iron (organic iron providing an additional 100 ppm Fe) or Pack (micronutrient package supplying an additional 4,000 IU/kg vitamin A, 50 ppm Zn, 100 ppm Fe, 100 ppm Cu, 150 µg/kg vitamin B12, 10 mg/kg vitamin B12, 13 mg/kg folic acid, and 500 mg/kg vitamin C) until sows were moved to the farrowing unit on approximately d 114. Top-dress was provided daily at 0.45 kg/sow two hours after morning feeding to minimize potential antagonisms. Blood was collected via ear prick on d 90 and before farrowing to determine Hb concentration using a portable HemoCue analyzer. Sows were classified as anemic when Hb was less than 10 g/dL. First, data were analyzed for main effects of treatment. The change in Hb from d 90 to 114 did not differ among treatments (P = 0.83), with increases of + 0.13, +0.02, and +0.13 g/dL for Control, Iron, and Pack, respectively. Supplementation did not affect final Hb concentration (P = 0.59) or influence pigs born alive (P = 0.27), stillbirths (P = 0.19), or mummified fetuses (P = 0.11). Next, data were analyzed for parity and BCS. Sows were classified as young (P0–P3), mature (P4–P6), or old (P7–P10). At baseline, Hb decreased with increasing parity (10.38a, 10.08ab, and 9.78b g/dL; P = 0.02) and remained different before farrowing (10.47a, 9.96b, and 10.34ab g/dL; P = 0.002). The change in Hb tended to decrease (P = 0.06) slightly in mature sows (-0.10 g/dL) but increased in old sows (+0.55 g/dL) compared with young sows (+0.10 g/dL). Hemoglobin and piglets born alive declined (P ≤ 0.05) as parity increased, and stillbirths were greater in old sows compared with young sows (P = 0.03), while mummified fetuses were not affected (P = 0.95). Neither BCS (P ≥ 0.05) nor the Parity×BCS interaction (P ≥ 0.05) influenced Hb. Results indicate that short-term supplementation with organic iron and micronutrients involved in Hb synthesis during late gestation did not improve Hb or farrowing performance compared with the control, and that Hb declined with increasing parity, regardless of body condition. These findings highlight parity as the main determinant of anemia risk and suggest that earlier nutritional intervention may be needed to improve iron status before farrowing.