Feeding levels during early gestation in a group-housing system for primiparous sows: impact on piglet birthweight and litter uniformity.

Objective: The current study investigated the impacts of different feeding regimes during early gestation on conception rate, litter traits, piglet birthweight, and litter uniformity in primiparous sows.

Methods: In total, 108 primiparous sows were inseminated and assigned to either a standard (1.9±0.5 kg/d, S) or high (2.9±0.8 kg/d, H) feeding levels during the first 35 days of gestation. The feeding regimes were categorized based on periods of gestation: 1 to 3, 4 to 15, and 16 to 35 days, resulting in four groups: standard-standard-standard (SSS, n = 26), standardstandard-high (SSH, n = 28), standard-high-high (SHH, n = 28), and high-high-high (HHH, n = 26). Afterwards, sows were placed into a group-housed system equipped with electronic sow feeders. The sows were weighed and assessed for backfat thickness and loin muscle depth at 0 and 35 days of gestation. At farrowing, data were collected on the total number of piglets born per litter, piglet birthweights, and the coefficient of variation of piglet birthweights.

Results: On average, sows gained 22.5±21.6 kg during the first 35 days of gestation, showing a positive correlation with backfat gain (r = 0.954; p = 0.006). The backfat gain in the HHH group was higher than in the SSS (p = 0.016) and the SSH groups (p = 0.023), but did not differ from the SHH group (p = 0.684). Conception rates did not show differences among the feeding regimes (p>0.05). Individual piglet birthweights in the HHH group were higher than those in the SSH group (p<0.001). Likewise, the percentage of piglets with birthweights <1,000 g in the HHH group was lower than that in the SSH group (p<0.001). However, the variation of piglet birthweight did not differ among the groups (p>0.05).

Conclusion: Increasing feeding levels in primiparous sows in a group-housed system during early pregnancy can effectively restore their body condition without any detrimental effects on subsequent litters.