237 Assessing the influence of sow loading strategy, functional teat number, and parity on litter performance

Abstract

Preweaning mortality presents a significant challenge for the swine industry, due to increased litter sizes that often exceed available functional teats. Therefore, it is imperative to understand the relationship between number of functional teats and piglet survival. Data from 1,261 multiparous F1 sows (DNA L241, DNA Genetics, Columbus, NE) were collected to investigate the impact of functional teat number, loading strategy, and parity on litter performance during lactation. Sow traits examined include functional teat count (FTC), parity, and loading strategy (LS), defined as the difference between the number of piglets started at 24-hour after birth and FTC. Key litter performance parameters included litter wean weight (WW), number of pigs weaned, and preweaning mortality (PWM), defined as the difference between the number of piglets started and weaned. Data were analyzed in R version 4.2.1 (R Core Team, 2022) using a linear mixed-effects model with fixed effects for parity, LS or FTC, and sow was included as a random litter effect. Compared to LS 0, WW is lower at LS -3 and -2 (P < 0.001), with no differences between LS 0 and LS -1, +1, +2, or +3 (P > 0.05). As LS increased from -3 to +1, number of pigs weaned increased (P < 0.01), with no differences between LS +1 to +3 (P > 0.05). Lower LS (-3, -2, -1) resulted in a reduction in pigs weaned compared to LS 0 (P < 0.001), while higher LS (+1, +2, +3) resulted in an increase in pigs weaned (P < 0.01). When increasing LS incrementally by 1, PWM from LS -3 to +1 did not differ (P > 0.05), however, PWM increased by 0.64 pigs from LS +1 to +2 (P < 0.01), with no further differences between LS +2 and +3. Compared to LS 0, PWM did not differ for LS -3 to +1 (P > 0.05), but LS +2 and +3 had higher rates (P < 0.001). FTC did not differ between parity groups (P > 0.05). Additionally, FTC had no impact on WW or number of pigs weaned, regardless of the number of pigs started (13-16; P > 0.05). Overall, increases in LS over 0 did not significantly affect WW, but positively influenced the number of pigs weaned, with variations in PWM emerging after +1 over FTC.