192. Influence of Timing of High Dietary Zinc Supplementation During Gestation on Sow Reproductive Outcomes and Lifetime Pig Performance.

Abstract

Supplemental Zn during gestation can enhance fetal development and piglet livability; but continuous high inclusion rates increase Zn excretion and may negatively impact the environment. Therefore, our objective was to use a precision-feeding approach to identify gestational periods in which supplemental Zn provides the greatest benefit while minimizing nutrient waste. The study was conducted on a commercial sow farm in southwestern Minnesota that recently re-populated. Sows (Acufast 276; n = 861) were mated to DNA 600 sires and blocked by parity category (Parity 1, Parity 2, and Parity 2 heat-skipped) then assigned to 1 of 4 treatments: (1) Control, ∼295 mg Zn/d throughout gestation; (2) Early, ∼1,255 mg Zn/d from ∼6 d pre-breeding to d 40 of gestation; (3) Late, ∼1,605 mg Zn/d from d 85 of gestation to farrowing; or (4) Early & Late, Early supplementation plus Late supplementation. Gestation and lactation performance were recorded, and data for the subsequent reproductive cycle data were captured from commercial farm records. Piglet outcomes (n = 12,595) were monitored from birth to weaning, and a subset of pigs (n = 1,189) was followed to market weight. For sow-level outcomes, statistical models included treatment, parity category, and their interaction as fixed effects. Continuous variables were analyzed using linear models with Type III ANOVA, whereas binary outcomes were analyzed using logistic regression with a binomial distribution. For piglet-level analyses, sow was included as a random effect in the mixed model. Dietary treatments did not interact with parity categories for most variables. Farrowing rate, and total piglets born, born alive, stillborn, mummies, and weaned per litter did not differ among treatments (P > 0.34). Pre-weaning mortality did not differ among treatments (Control: 11.19%, Early: 12.20%, Early & Late: 12.25%, Late: 11.56%; P = 0.49). Weaning weight, average daily gain, market weight, carcass weight, and backfat depth at harvest also did not differ (P > 0.09). However, wean-to-finish mortality was lower in pigs from sows receiving the Late treatment (2.3%) compared with Control (7.5%; P = 0.023), whereas Early (5.0%) and Early & Late (3.0%) did not differ from Control. Reproductive performance in the subsequent cycle was not affected by treatment (P > 0.17). While elevated gestational Zn supplementation did not improve offspring growth, pre-weaning survival or reproductive performance of sows in this study, improved postweaning survival of pigs due to Zn supplementation in late gestation may justify the targeted use of elevated dietary Zn in late gestation.