# Microvillus in LBW Meishan Piglets Preserved Microvillus Integrity Alongside Impaired Intestinal Barrier Function in Low-Birth-Weight Meishan Neonatal Piglets

## TL;DR

Low-birth-weight Meishan piglets have impaired intestinal barriers but maintain microvillus structure, possibly explaining their higher survival rates.

## Contribution

This study identifies preserved microvillus integrity as a key adaptive trait in low-birth-weight Meishan piglets with compromised intestinal function.

## Key findings

- LBW piglets showed reduced villus height and antioxidant capacity compared to NBW piglets.
- Microvillus structure remained intact despite mitochondrial swelling in LBW piglets.
- LBW piglets had lower levels of tight junction proteins and mucin 2, indicating impaired intestinal barrier function.

## Abstract

The aim of this study was to evaluate the impact of low birth weight on intestinal barrier function in Meishan neonatal piglets and to compare structural and functional parameters between low-birth-weight (LBW) and normal-birth-weight (NBW) individuals. These parameters were classified into categories reflecting intestinal health status based on expert knowledge. Most structural and functional indicators were impaired in LBW piglets, accounting for significant alterations in barrier integrity, though microvillus structure remained notably intact. Negatively affected aspects included villus morphology, antioxidant capacity, and tight junction protein expression. A subsequent analytical approach using morphological, molecular, and biochemical assays was performed to objectively quantify these differences. Establishing an expert-based assessment of intestinal development is important for advancing strategies aimed at improving neonatal piglet survival. It forms the basis for detecting critical physiological deficits through biomarker analysis and supporting targeted interventions via precision husbandry.

Despite lower birth weight, Meishan piglets exhibit a notably higher pre-weaning survival rate compared to Western commercial breeds. This study aimed to evaluate the effect of low birth weight (LBW) on intestinal barrier function in Meishan neonates. Six pairs of neonatal piglets (one normal birth weight, NBW: 0.85 ± 0.06 kg; one LBW: 0.65 ± 0.02 kg) from the same sow were euthanized at birth prior to suckling. Morphological parameters, goblet cell density, antioxidant enzyme activities, cytokine gene expression, and tight junction protein levels in the small intestine (SI) were assessed. Results showed that LBW piglets had a significantly higher SI length-to-body weight ratio (p < 0.05), along with reduced villus height, villus height-to-crypt depth ratio, and villus surface area in the jejunum and ileum (p < 0.01). Notably, microvillus structure remained intact despite the presence of mitochondrial swelling. LBW piglets also exhibited decreased goblet cell numbers, lower antioxidant capacity, dysregulated expression of cytokines (CD8, IFNγ, IL4, IL2), and reduced levels of mucin 2, ZO-1, and occludin (p < 0.05). In conclusion, although LBW Meishan piglets showed impairments in multiple aspects of intestinal barrier function, the structural integrity of the microvillus was preserved, which may contribute to their higher survival rate and represents a key adaptive advantage over commercial pig breeds.