# Ferrous Glycinate (Fe-Gly) Supplementation Improves Growth Performance by Modulating Intestinal Immunity and Microbiota in Weaned Piglets

## TL;DR

Ferrous glycinate improves piglet growth and gut health by reducing inflammation and promoting beneficial bacteria.

## Contribution

Fe-Gly is shown to enhance piglet growth and intestinal health more effectively than other iron sources.

## Key findings

- Fe-Gly significantly increased body weight and reduced diarrhea in weaned piglets.
- Fe-Gly improved intestinal health by increasing Lactobacillus and reducing harmful bacteria.
- Fe-Gly enhanced iron status and reduced residual iron in the gut compared to other iron sources.

## Abstract

Iron is an essential nutrient for animals, playing a vital role in maintaining normal physiological functions. Thus, it is necessary to study how iron affects animal growth, development, and intestinal health, as well as the underlying mechanisms. In the swine industry, iron nutrition imbalance during the weaning period of piglets can impair intestinal health, lead to growth retardation, and severely reduce economic benefits. This study aimed to explore the effects and main mechanisms of different iron sources added to diets on the growth performance and intestinal health of weaned piglets. The results demonstrate that ferrous glycinate (Fe-Gly) not only effectively promotes the growth and intestinal epithelial development of piglets, but also reduces intestinal inflammation, enhances intestinal health, and lowers the risk of diarrhea. Additionally, due to its higher bioavailability, Fe-Gly leaves less residual iron in the intestines. This creates a more favorable environment for the growth of beneficial bacteria such as Lactobacillus, thereby further improving intestinal health. These findings deepen the understanding of the relationship between iron sources and intestinal health and provide a scientific basis for the application of efficient and healthy iron sources in the livestock industry.

Iron is an essential nutrient for piglets, but iron sources vary greatly in bioavailability, and their effects on intestinal health remain unclear. In this study, 21-day-old weaned piglets were used to compare the effects of different iron sources (ferrous sulfate (FeSO4), ferric ammonium citrate (FAC), and ferrous glycinate (Fe-Gly)) on growth performance, intestinal inflammation, and gut microbiota. Compared to the FeSO4 group, the Fe-Gly group significantly increased the body weight of piglets at 35 days (p < 0.05), promoted the average daily feed intake (ADFI) and average daily gain (ADG) of piglets from day 21 to 35 (p < 0.01), and also markedly reduced the diarrhea rate of piglets (p < 0.01). Meanwhile, although FAC increased growth performance-related indicators (ADG, ADFI) in piglets, there was no significant statistical difference compared with FeSO4 (p > 0.10). Moreover, Fe-Gly supplementation significantly elevated serum iron levels and total iron-binding capacity (p < 0.01), while significantly reducing the iron content in colonic chyme (p < 0.0001). Both the Fe-Gly and FAC significantly improved the anti-inflammatory and antioxidant capacities of the piglets (p < 0.01). Interestingly, Fe-Gly primarily increased the abundance of Lactobacillus, thereby reducing the abundance of harmful bacteria such as Escherichia coli. Functional prediction using PICRUSt2 revealed that Fe-Gly supplementation tended to elevate the relative abundance of gut bacteria capable of carbohydrate metabolism and amino acid synthesis. In conclusion, this study demonstrated that dietary Fe-Gly supplementation improved systemic iron status, effectively reduce residual iron in the intestine, inhibit the proliferation of pathogenic bacteria in the gut, promote the growth performance and intestinal health of piglets, and reduce the diarrhea rate.