There is a commonly held belief among many pig farmers that first parity sows should be "loaded up" with piglets to prevent unsuckled teats. The theory being that unsuckled teats in the first parity have a negative impact on subsequent milk production. While this management practice is used in a number of sow farms across the United States, this article will examine the conflicting science regarding the topic.
Canadian and European scientists reported average piglet weaning weight was reduced for Parity 2 sows when piglets nursed teats previously unsuckled (versus suckled) in Parity 1 (Farmer et al., 2012). Looking deeper at the study's methodology, the authors' limited access to all but six teats per sow for each treatment (unsuckled versus suckled in first parity).
Piglets were cross-fostered so that every sow started lactation with seven piglets. Hence, litter size reared was lower than what we typically see in commercial farms today. The authors further reported differences in lactation feed intake between treatments. Parity 2 sows whose teats were unsuckled (versus suckled) had lower lactation feed intake during weeks one, two and three of lactation.
Perhaps differences in lactation feed intake between the treatments partially explains why sows with unsuckled teats did not milk as well as sows whose teats had previously been suckled. In contrast to Farmer et al. (2012), Lannom (2018) found no differences in average piglet weaning weight for sows when teats were suckled or unsuckled in the previous parity. In the study by Lannom (2018), litters were cross-fostered so that each sow nursed eight to 10 piglets.
While the studies by Farmer et al. (2012) and Lannom (2018) equalized piglets nursing across treatments and restricted access to certain teats, Guo et al. (2019) cross-fostered first parity litters so that sows were nursing either 10 or 13 piglets. This scenario perhaps better exemplifies what we may see in commercial production. Guo et al. (2019) reported no differences in second parity average piglet weaning weights when sows nursed 10 or 13 piglets in the first parity.
Taken together, research results do not strongly support the belief that unsuckled teats in Parity 1 impair subsequent milk production.
Research has shown "loading up" first parity sows with piglets can impair subsequent reproduction. Guo et al. (2019) reported first parity sows nursing 13 piglets tended to have poorer herd retention when compared to sows nursing 10 piglets. Besides sow retention, "loading up" first parity sows with piglets can impair subsequent litter size.
A recent field study we conducted (about 230,000 litters) showed Parity 1 sows that weaned a greater number of pigs farrowed fewer piglets in the second parity. These findings are likely explained by lactation nutrient intake. First parity sows may struggle to consume enough energy and nutrients during lactation to support subsequent reproduction. "Loading up" first parity sows with additional piglets exacerbates this problem.
Given the body of scientific literature, our current recommendation is to not "load up" Parity 1 females with piglets. Questions or comments can be sent to Mark Knauer.