215 Assessment of the relationship between lactation feeding patterns, litter performance measures, and sow characteristics on sow farrowing efficiency metrics

Abstract Introduction: The number of piglets weaned per sow per year (PSY) is commonly used as a benchmark to track changes in herd performance or to compare performance between herds [1,2,3]. While PSY is a valuable measure of herd productivity, it does not adequately reflect sow longevity or future reproductive performance [1]. Sow productivity can be influenced by various individual predictors [3,4]. Our objective was to assess individual sow predictors associated with sow efficiency defined as wean-to-estrus interval (days), sows bred within 7 days post-weaning (%), and subsequent farrowing. Methods: Experimental data was sourced from six lactation trials conducted between 2021 and 2022 on a commercial sow farm. The animals were housed in the same lactation rooms, had same genetics, and had no PRRSV or PEDV health challenges. The final dataset had 4,300 observations, including productivity performance, daily lactation feed intake, sow and litter weights, caliper measurements, and subsequent performance. Generalized linear regression models were built using R® program to identify factors with each outcome. A total of 23 predictors were evaluated in each model and trial-id was included as a random effect. Each model was built using a manual stepwise forward selection, interactions and confounders were tested based on biological relevance, and predictors with p-values <0.05 retained in the final model. Pairwise comparison was tested using t-tests with Tukey-Kramer adjustment, considering p-values <0.05 as statistically significant. Results: Predictors associated with WEI included parity (P <0.001), piglets after cross-fostering (P =0.01), ADFI in the first three days of lactation (P = 0.01) and lactation ADFI (P = 0.019) with farrowing season as confounder (P = 0.03). Sows with more than 16 piglets after cross-fostering had 1.3-day increase in WEI (P = 0.01). Lactation ADFI <10lbs in the first 3 days was associated with 1-day increase in WEI (P <0.001). Predictors associated with sows bred within seven days post-weaning included parity (P = 0.05) and interaction with litter birth weight (P = 0.05). For subsequent farrowing, predictors included litter size (P = 0.02), stillborn rate (P = 0.01), ADFI during the first week of lactation (P = 0.01) and body weight change (P = 0.01). Sows with at least one stillborn showed a 7% decrease in subsequent farrowing (P = 0.01), while those with more than 16 piglets after cross-fostering had 12% decrease in farrowing rate (P = 0.02). Conclusion: This study identified relevant predictors of sow efficiency and performance. These findings present opportunities to develop targeted management, nutritional, and reproductive strategies to enhance sow longevity and productivity. References: 1 Koketsu Y, Tani S, Iida R. Factors for improving reproductive performance of sows and herd productivity in commercial breeding herds. Porcine Health Manag. 2017; 3:1. 2. Hyunwoong, Jo., Han-Min, Kim., Beob, Gyun, Kim. (2023). The effect of feed intake during lactation on the wean-to-estrus interval of sows. doi: 10.5187/ait.2021.10.1.45. 3. Koketsu, Y., & Iida, R. (2020). Farm data analysis for lifetime performance components of sows and their predictors in breeding herds. Porcine Health Management, 6, 1-12. 4. Estrada, J., Johnson, D.C., Kyle, K.L., Perez, J., Parr, E., Welch, M.W., Neill, C., Peterson, B.A. and Boler, D.D., 2024. Characterizing sow feed intake during lactation to explain litter and subsequent farrowing performance. Journal of Animal Science, 102, p. skae093.