# Dietary Supplementation with Protocatechuic Acid and a Complex Eucommia ulmoides Leaf Extract Differentially Enhanced Reproductive Performance and Modulated Gut Microbiota in Late-Pregnancy Sows

## TL;DR

Adding protocatechuic acid and a leaf extract to sows' diets improved their reproductive performance and colostrum quality by changing gut bacteria linked to metabolism and inflammation.

## Contribution

This study is the first to show how PCA and PCA-rich extracts improve sow reproduction and gut microbiota during late pregnancy.

## Key findings

- PCA and EU supplementation increased litter weight and healthy piglets at birth.
- PCA improved insulin sensitivity and increased Bacteroidetes abundance in sows.
- Both PCA and EU reduced Paraprevotella abundance, while each increased specific beneficial gut bacteria.

## Abstract

Fatness management in late-pregnancy sows is critical for optimizing reproductive performance and subsequent productivity, as it is closely associated with maternal metabolic status. Given the essential roles of gut microbiota in host metabolic pathways, microbiota-related research has received increasing attention over the past few decades. Our previous study demonstrated that protocatechuic acid (PCA) significantly improved glycolipid metabolism in a murine model, but relevant applications of PCA in sows remain largely unexplored. To provide a scientific basis for the rational utilization of PCA and PCA-rich natural resources, this study aims to investigate the effects of dietary supplementation with PCA and PCA-rich Eucommia ulmoides leaf extract (EU) on reproductive performance in late-pregnancy sows. Results in this paper showed that dietary supplementation with PCA and PCA-rich EU enhanced reproductive performance and colostrum immunoglobulin levels in late-pregnancy sows, which were potentially mediated through alteration of maternal gut microbiota linked to inflammation and glucose metabolism. This original manuscript provides scientific references for the rational utilization of PCA, EU, and other PCA-rich natural resources in sow feeding programs.

Nutrition during late pregnancy plays a critical role in fetal development. This study was conducted to investigate the effects and underlying mechanisms of protocatechuic acid (PCA) and PCA-rich Eucommia ulmoides leaf extract (EU) on reproductive performance using late-pregnancy sows as a model. A total of 30 sows (Landrace × Yorkshire; average parity: 3–4) with similar body condition (assessed as a score of 4 on a 5-point scale) were randomly assigned to three treatments (n = 10 per group) from day 80 of gestation until farrowing and fed either a basal diet, a basal diet supplemented with 200 g/t of PCA, or 1000 g/t of EU. Results demonstrated that dietary supplementation with PCA and EU, which delivered a negligible amount of PCA but contained other bioactive phytochemicals such as chlorogenic acid, significantly increased litter weight at birth and the number of healthy piglets (p < 0.05), along with elevated levels of colostral immunoglobulins and reduced serum interleukin (IL)-6 concentrations (p < 0.05). Furthermore, PCA supplementation was associated with a decrease in fasting glucose levels and improved insulin sensitivity (p < 0.05), accompanied by an increased relative abundance of Bacteroidetes (p < 0.05). Analysis of gut microbial composition revealed that both PCA and EU reduced the relative abundance of Paraprevotella (p < 0.05), while PCA increased the abundance of the dgA11_gut_group (p < 0.05), and EU enriched Caldicoprobacter (p < 0.05). Correlation analysis indicated that PCA- and EU-modulated genera, such as Lysinibacillus, were positively associated with colostrum lactose and colostrum fat but negatively correlated with the number of somatic cells, colostrum protein, degreased dry matter, total solids, and urea nitrogen (p < 0.05). In conclusion, dietary supplementation with PCA and EU differentially enhanced reproductive performance and colostrum immunoglobulins, at least partially, through the modulation of inflammation and glucose metabolism-related gut microbiota in late-pregnancy sows.