# Effect of a Reduced-Protein Diet Supplemented with Essential Amino Acids on the Muscle Proteome of Female and Entire Male Finishing Pigs

## TL;DR

This study shows that reducing protein in pig diets with amino acid supplements affects muscle and fat development similarly in male and female pigs.

## Contribution

The study is the first to examine the muscle proteome response to low-protein diets in fast-growing Duroc sire line finishing pigs of both sexes.

## Key findings

- Low-protein diets increased lipogenesis and decreased muscle growth in both male and female pigs.
- Control males showed higher muscle-related protein abundance compared to females.
- Both sexes reacted similarly to the low-protein diet, with no major differences in physiological responses.

## Abstract

Dietary Crude protein (CP) reduction with amino acid (AA) supplementation pig feeding is an interesting cost-reducing strategy with benefits to the environment. Physiological studies addressing fast-growing Duroc sire line finishing pigs of both sexes are non-existent. We hypothesized that entire males and females will be similarly affected by such a strategy. We conducted a study with 60 male and 60 female finishing pigs subjected to two isoenergetic diets differing in CP content (145 and 125 g CP/kg with AA supplementation, control, and low-CP). We established proteomics profiles of the Semimembranosus muscle. Males and females reacted alike to the two diets, although low CP diet led to advanced lipogenesis and decreased muscle growth. The strategy can be used in fast-growing Duroc sire line genotypes of both sexes in the finishing phase, albeit that implies a slight modification of pathways related to muscle protein and lipid synthesis without compromising productive performance.

Crude protein (CP) decrease coupled to amino acid (AAs) supplementation is interesting for swine nutrition. A proteomics approach unraveled physiological events underlying differences between sexes fed two diets: control and low CP in fast-growing Duroc X (Landrace X Large white) finishing pigs. Sixty animals per sex were distributed in pens (five replicate pens/group), fed ad libitum with two isoenergetic diets (145 vs. 125 g CP/kg with AA supplementation; control and low-CP) for 42 days. Semimembranosus muscle was sampled. Five samples per group were used for Label Free proteomics. Four comparisons were considered: Control Males vs. Control Females; Control Females vs. Low CP females; Control males vs. Low CP males, and Low CP males vs. Low CP females, identifying, respectively, 26, 19, 12, and 11 DAPs (Differentially Accumulated Proteins). Control males had higher abundance of proteins related to cell differentiation and growth compared to females, highlighting continual muscle accretion in the former and lipogenesis onset in the latter. Control females and males had increased DAPs related to tissue growth and differentiation compared to Low CP animals that had increased lipid accretion. Both sexes reacted similarly to the two diets. Low CP diet led to advanced lipogenesis and decreased muscle accretion pathways.