PSI-3 - Effect of feed and water consumption patterns during the lactation period on wean-to-estrus interval in weaned sows

Abstract: There is sufficient evidence that adequate feed and water consumption during the lactation period positively influences sow body condition at weaning. Optimum body condition score after the lactation period decreases sow wean-to-estrus interval and non-productive sow days and promotes sow reproductive performance in the following reproductive cycle, in general. However, feed and water intake patterns have not been extensively studied in commercial sow research; thus, the objective of this study was to determine the effect of feed and water consumption patterns in the lactation period on wean-to-estrus interval in weaned sows. This trial was conducted in a commercial sow farm located in southwestern Minnesota in March 2023. Each lactation feeder was outfitted with a MealMeter 2.0 device (PigEasy, LLC, Templeton, Iowa, United States), which uses a rotating feed dispenser to release feed ad libitum at the request of each sow. In addition, the MealMeter 2.0 device utilizes sensors to track the number of times feed and water were accessed at 15-minute time intervals across the entire lactation period. Average daily feed (ADF) and water accessions (ADW) were summarized for each sow during the lactation period (N = 84 sows). Root mean squared error (RMSE_F and RMSE_W for feed and water accessions, respectively) was calculated from the residuals of the regression between days post-farrowing and ADF and ADW for each sow and was considered a measure of variation in feed and water accessions during the lactation period. Moreover, the number of days from weaning to the first estrus was recorded and defined as the wean-to-estrus interval (WTE). Due to the distribution of WTE, sows with a WTE ≤ 5 days and WTE > 5 days were separated into a binary classifier (0 = WTE ≤ 5 days and 1 = WTE > 5 days). The relationship between each feed and water measurement and WTE class was estimated using a logistic regression model fit with R Statistical Software. Average daily feed and water accessions were negatively associated with WTE class (P-value = 0.07 and 0.04, respectively), indicating that as feed and water accessions increase, the probability of observing a WTE greater than 5 days decreases. In addition, RMSE_F and RMSE_W were also negatively associated with WTE class, which suggests that as the variation in each measure across the lactation period increases, the probability of observing a WTE greater than 5 days is reduced. This result was not expected and, thus, requires further investigation. Nonetheless, results from this study suggest that the mean and variation of daily feed and water accessions are associated with WTE and sufficient consumption of nutrients during the lactation period is critical to reducing the number of days to first estrus in weaned sows.