# Characterizing the Dynamic Protein and Amino Acid Deposition in Tissues of Pregnant Gilts: Implications for Stage-Specific Nutritional Strategies

## TL;DR

This study shows that pregnant pigs need changing diets during pregnancy to match protein and amino acid needs, which can improve piglet development and farm efficiency.

## Contribution

A new model was developed to track dynamic changes in protein and amino acid deposition in pregnant gilts, challenging constant-rate assumptions.

## Key findings

- Protein deposition fluctuates significantly during gestation, requiring stage-specific dietary adjustments.
- Early gestation may need higher protein and amino acid intake than previously assumed.
- Amino acid profiles shift during late gestation, indicating changing nutritional demands.

## Abstract

Ensuring that pregnant sows receive proper nutrition is crucial for their health and the development of their piglets. Current gestation models assume that protein and amino acids are deposited at a constant rate, but experimental data show that deposition rates vary across different stages. By developing a new model that accounts for changes in tissue growth and composition, we found that protein deposition fluctuates significantly throughout gestation. Our findings suggest that sows may require different diets at different times, particularly more protein and amino acids early in pregnancy than previously thought. Additionally, we identified gaps in understanding protein deposition in both the sow and conceptus, which, by studying further, could lead to improved feeding strategies that better support maternal and fetal development. By advancing knowledge of protein deposition dynamics, our research lays the foundation for precision feeding strategies that enhance pig health, reproductive outcomes, and farm efficiency.

Understanding protein and amino acid deposition in pregnant gilts is important for developing nutritional strategies that meet these demands and enhance reproductive performance. Current models, such as the NRC (2012) gestating sow model, assume a constant proportional protein and amino acid content in tissues throughout pregnancy. However, empirical data suggest that gestational tissue growth and composition change dynamically. In this study, we developed a gestation model that characterizes the dynamic changes in growth, crude protein, and amino acid deposition throughout gestation. Based on a systematized search of published data, mathematical functions were developed to estimate daily protein and amino acid deposition in key tissues, including allantoic and amniotic fluid, uterus, placenta, fetus, mammary gland, and maternal body. Our results suggest that dietary crude protein levels and amino acid profiles should be adjusted to meet metabolic demands, particularly in early gestation, where a potential nutritional deficiency was identified. Additionally, the amino acid profile of deposited protein shifts during late gestation, suggesting a changing demand for specific amino acids. These findings challenge existing models and highlight the need for adaptive dietary strategies that better align with pregnancy’s biological demands. By refining protein and amino acid deposition estimates, this study provides a framework guiding future research on precision feeding, ultimately improving gilt and sow reproductive performance.