194. Evaluating the Timing of Nutrient Enrichment in Late Gestation on Reproductive Outcomes and Sow Mortality Under Commercial Conditions.

Abstract Previous research has demonstrated benefits of nutrient-enriched late-gestation diets for improving sow micronutrient status and farrowing outcomes; however, the optimal timing of implementation and evaluation under commercial conditions in different genetic lines remain unclear. The objective of this study was to evaluate the effects of timing of a nutrient-enriched late-gestation diet on reproductive performance and sow mortality in commercial sows. A total of 1,237 AcuFast sows (parity 0–9; average parity 2) were allotted by parity to one of four dietary treatments in late gestation. The control diet (CON) contained 12.7% CP, 0.58% SID Lys, and industry-standard organic trace minerals and vitamins. The nutrient-enriched diet (LGPHASE) contained 16% CP, 0.90% SID Lys, 2× the control level of industry-standard organic trace minerals and vitamins except selenium, and 500 mg/kg vitamin C. Sows were assigned to one of four treatments: 1) CON (n = 308); 2) LGPHASE initiated on day 60 of gestation (LGPHASE60; n = 310); 3) LGPHASE initiated on day 80 of gestation (LGPHASE80; n = 310); or 4) LGPHASE initiated on day 100 of gestation (LGPHASE100; n = 309). All sows received a common lactation diet. Data were analyzed using PROC MIXED of SAS (SAS Inst. Inc., Cary, NC), with sow as the experimental unit. Sow mortality was tracked from day 60 of gestation through 35 days post-weaning. Overall reproductive performance was not affected by dietary treatment. When evaluated by parity, sows of parity ≥4 had lower stillborn rates when fed LGPHASE100 (6.5%) and tended to have lower stillborn rates when fed LGPHASE60 (7.2%) or LGPHASE80 (6.6%) than CON (8.4%; P = 0.052). When stratified by prolificacy, sows rearing ≥20 total pigs had reduced stillborn rates when fed LGPHASE60 (6.8%) than CON (11.6%), whereas LGPHASE80 (7.6%) and LGPHASE100 (8.1%) were intermediate (P = 0.027). Sow mortality was lower in LGPHASE60 group (1.2%) than both CON (3.6%) and LGPHASE100 (3.6%), whereas LGPHASE80 (2.8%) was intermediate (P < 0.05). In conclusion, introducing a nutrient-enriched diet beginning at day 60 of gestation improved reproductive outcomes in high-performing sows and reduced sow mortality, suggesting that greater nutritional support during late gestation may be required as sow prolificacy continues to increase.