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Reducing dietary protein is a recognized strategy to lower nitrogen emissions and feed costs in pig production, but questions remain about its impact on growth performance and meat quality.
Objective: This study investigated the effects of low protein diets on growth, carcass traits, gut microbiota, and metabolism in finishing pigs.
Methods: A total of 180 crossbred finishing pigs (Duroc × Liang Guang Small Spotted; average initial body weight ~85 kg) were assigned to three dietary regimens for 35 days: a control diet (15.5% crude protein), a moderately reduced protein diet (14.5% CP), and a further reduced protein diet (13.5% CP). All diets were balanced with essential amino acids to meet requirements.
Results: Growth performance and nutrient digestibility were maintained across treatments, confirming that moderate protein reduction did not compromise production efficiency. However, carcass and metabolic traits were influenced by dietary protein level. Pigs fed the 14.5% CP diet exhibited increased backfat thickness, while pigs on the 13.5% CP diet showed altered muscle composition, with reduced concentrations of certain fatty acids and essential amino acids. Gut microbiota profiles shifted with protein reduction: control pigs were enriched in Prevotella, Faecalibacterium, and Plesiomonas, whereas the 14.5% CP diet favored Eubacteriaceae, Christensenellaceae, and Clostridia. Serum metabolomics revealed that moderate protein reduction affected bile secretion and cholesterol metabolism, while further reduction suppressed cholesterol metabolism and bile acid biosynthesis, with indications of altered amino acid metabolism.
Conclusion: Moderate reduction of dietary protein, when balanced with essential amino acids, sustains growth performance, reduces nitrogen excretion, and beneficially modulates muscle composition, gut microbiota, and host metabolic pathways. These findings highlight low protein feeding strategies as a viable approach to improve pork quality and support sustainable pig production.
He T, Ye Z, Zhou C, Jiang S, Yang L, Liu Y, Liu S, Zhao J, Long S, Chen Z. Moderate Reduction in Dietary Protein Improves Muscle Composition and Modulates Gut Microbiota and Serum Metabolome Without Compromising Growth in Finishing Pigs. Animals (Basel). 2025; 15(22):3234. doi: 10.3390/ani15223234