Early Growth and Protein-Energy Metabolism in Chicken Lines Divergently Selected on Ultimate pH

Abstract

In chickens, a divergent selection on the Pectoralis major pHu allowed the creation of the pHu+ and pHu− lines, which represent a unique model for studying the biological control of carbohydrate storage in muscle. The present study aimed to describe the early mechanisms involved in the establishment of pHu+ and pHu− phenotypes. At hatching, pHu+ chicks were slightly heavier but exhibited lower plasma glucose and triglyceride and higher uric acid. After 5 days, pHu+ chicks exhibited higher breast meat yield compared to pHu− while their body weight was no different. At both ages, in vivo muscle glycogen content was lower in pHu+ than in pHu− muscles. The lower ability of pHu+ chicks to store carbohydrate in their muscle was associated with the increased expression of SLC2A1 and SLC2A3 genes coding glucose transporters 1 and 3, and of CS and LDHα coding key enzymes of oxidative and glycolytic pathways, respectively. Reduced muscle glycogen content at hatching of the pHu+ was concomitant with higher activation by phosphorylation of S6 kinase 1/ribosomal protein S6 pathway, known to activate protein synthesis in chicken muscle. In conclusion, differences observed in muscle at slaughter age in the pHu+ and pHu− lines are already present at hatching. They are associated with several changes related to both carbohydrate and protein metabolism, which are likely to affect their ability to use eggs or exogenous nutrients for muscle growth or energy storage.

Nutrient sources differ in the fertilised eggs of two divergent broiler lines selected for meat ultimate pH

“…This environment can affect the physiological and morphological development of embryos, with substantial effects on the development of chick phenotypes 17 . At hatching, the divergent lines selected based on breast meat pHu already present distinct phenotypic and metabolic features 5 , which may result from quantitative and qualitative differences in available nutrients in ovo and/or their use by the embryo. To test this hypothesis, we first investigated the potential line-related differences in egg characteristics, including the composition of the yolk and amniotic fluid, which are the two main sources of nutrients during egg incubation.…”

“…This difference was associated with specific blood and muscle metabolic profiles, indicating greater protein catabolism and lipid oxidation in the pHu+ line and greater activation of the glycolytic pathway in the pHu− line 4 . Recently, it has been shown that the divergent metabolic pattern of pHu+ and pHu− lines is set in early during development since, at hatching, the two lines already show differences in protein and energy metabolism that could be related to a different ability to use energy sources at the muscle level 5 .…”

Mitochondrial and Glycolytic Capacity of Peripheral Blood Mononuclear Cells Isolated From Diverse Poultry Genetic Lines: Optimization and Assessment

“…For example, in chickens selected for divergence in abdominal fat pad by Dupont et al (27), changes in liver metabolism were observed to favor lipogenesis and ultimately greater abdominal fat deposition. Meat quality-focused work in broilers has shown that divergent selection for breast ultimate pH at harvest resulted in differences in carbohydrate and protein metabolism, specifically by altering glucose storage and key enzymes in both the mitochondrial respiration and glycolytic pathways (28). Additionally, lipid metabolism is shown to be dysregulated in broilers affected by the woody breast myopathy, an unintended consequence of selection for increased breast yield (29).…”

Reconstruction of a generic genome-scale metabolic network for chicken: Investigating network connectivity and finding potential biomarkers

“…Finally, in 2004, the genome sequencing of chicken wherein scientists had estimated 20000 to 23000 genes for chicken was released [ 23 ]. As a potential source of protein, many efforts have been made for both embryonic and adult chickens, ranging from the growth rate to meat yield, and the feeding strategies and efficiencies [ 24 – 26 ]. Studies have shown that breast muscle’s in vivo glycogen content correlates with meat quality [ 24 ].…”

“…As a potential source of protein, many efforts have been made for both embryonic and adult chickens, ranging from the growth rate to meat yield, and the feeding strategies and efficiencies [ 24 – 26 ]. Studies have shown that breast muscle’s in vivo glycogen content correlates with meat quality [ 24 ]. On the other hand, it has been reviewed that continuous progress in optimizing meat and egg production has led to various disorders in metabolism and reproduction; then it has negative implications on humans as a result of consuming chicken’s meat and egg [ 25 ].…”