Researchers have uncovered a fascinating connection between the digestive system and the quality of chicken meat. By studying two divergent chicken lines selected for their breast muscle’s ultimate pH – a key indicator of meat quality – the study reveals how differences in gut function and microbiome composition can impact the storage of muscle glycogen, a critical determinant of meat tenderness and color. This groundbreaking research sheds light on the complex interplay between gut health and muscular development, offering insights that could help the poultry industry enhance the overall quality and consistency of chicken products. Glycogen, microbiome, and poultry farming are some of the key concepts explored in this study.
Gut Health and Muscle Glycogen: A Surprising Connection
The quality of chicken meat is heavily influenced by the amount of glycogen stored in the muscle at the time of slaughter. Glycogen is a complex carbohydrate that serves as a readily available energy source for muscle cells. When muscle glycogen is high, it leads to a more acidic, pale, and exudative meat, known as PSE-like meat. Conversely, when glycogen levels are low, it results in darker, firmer, and drier meat, referred to as DFD-like meat.
To better understand the factors that influence muscle glycogen levels, researchers investigated two chicken lines that were selectively bred for divergent ultimate pH (pHu) of the breast meat – a proxy for glycogen content. The pHu- line had significantly higher muscle glycogen compared to the pHu+ line, which had lower glycogen reserves.
Decoding the Digestive Differences
The researchers discovered that the pHu- line, with its higher muscle glycogen, also exhibited several distinct features in its digestive system:
1. Larger Proventriculus and Gizzard: The pHu- line had a 28.7% greater relative weight of the proventriculus (the first part of the stomach) and gizzard compared to the pHu+ line. This suggests better enzymatic, chemical, and mechanical digestion in the pHu- line.
2. Higher Nutrient Absorption: The pHu- line showed greater digestibility of nitrogen and calcium, indicating more efficient nutrient absorption.
3. Increased Mucosal Thickness: The pHu- line tended to have greater mucosal thickness and villus height in the jejunum, the main site of nutrient absorption, further supporting the enhanced digestive capacity.
Microbiome Differences and Metabolic Implications
The researchers also examined the composition of the caecal microbiome, which is known to play a crucial role in chicken digestion and performance. While the overall bacterial diversity was similar between the two lines, they identified three bacterial genera that differed significantly in abundance:
1. Lachnospira and Lachnospiraceae UCG-010: These genera, which were more abundant in the pHu- line, are known to produce short-chain fatty acids like butyrate and propionate, promoting gut health and energy metabolism.
2. Caproiciproducens: This genus, more abundant in the pHu+ line, is capable of producing caproic acid, which can be used as an energy source.
These subtle microbiome differences were also associated with alterations in two key metabolic pathways in the prokaryotes:
1. Carbon Fixation: This process, which is crucial for energy production, was more abundant in the pHu- line.
2. Citrate Cycle: This central metabolic pathway was more represented in the pHu+ line.
Unraveling the Genetic Connections
The researchers also explored the transcriptional profiles of the jejunum, the primary site of nutrient absorption, and identified 149 genes that were differentially expressed between the two lines. Some of these genes were linked to:
1. Immunity and Hormonal Response: Genes related to the immune system and hormonal regulation, such as those involved in the traitlocus’>quantitative trait loci (QTLs) controlling meat pH and selection signatures in the divergent lines. One notable example is the GHRL gene, which encodes the appetite-regulating hormone ghrelin.
Unraveling the Complexity of Meat Quality
This study highlights the intricate relationship between the digestive system, gut microbiome, and muscle glycogen content – a crucial determinant of chicken meat quality. By understanding these connections, researchers can potentially develop strategies to optimize poultry production and improve the consistency and desirable attributes of chicken meat, benefiting both the industry and consumers.
As the researchers note, the next step will be to further explore the interplay between the transcriptional changes observed in the intestine and the muscle, shedding more light on the complex mechanisms underlying the differences in muscle glycogen storage and meat quality.
Author credit: This article is based on research by Philippe Bochereau, Sarah Maman Haddad, Julien Pichon, Christelle Rossignol, Agnès Narcy, Sonia Métayer-Coustard, Cécile Berri, Elisabeth Le Bihan-Duval.
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