The continuous increase in poultry production over the last decades to meet the high growing demand and provide food security has attracted much concern due to the recent negative impacts of the most challenging environmental stressor, heat stress (HS), on birds. The poultry industry has responded by adopting different environmental strategies such as the use of environmentally controlled sheds and modern ventilation systems. However, such strategies are not long-term solutions and it cost so much for farmers to practice. The detrimental effects of HS include the reduction in growth, deterioration of meat quality as it reduces water-holding capacity, pH and increases drip loss in meat consequently changing the normal color, taste and texture of chicken meat. HS causes poor meat quality by impairing protein synthesis and augmenting undesirable fat in meat. Studies previously conducted show that HS negatively affects the skeletal muscle growth and development by changing its effects on myogenic regulatory factors, insulin growth factor-1, and heat-shock proteins. The focus of this article is in 3-fold: (1) to identify the mechanism of heat stress that causes meat production and quality loss in chicken; (2) to discuss the physiological, metabolic and genetic changes triggered by HS causing setback to the world poultry industry; (3) to identify the research gaps to be addressed in future studies.

Oxidative stress is inevitable in poultry production, and it affects the physiological, behavioral and biochemical status of growing chicken which ultimately deteriorates meat quality. Appearance, texture, juiciness, tenderness and odor are responsible for the overall meat quality as they are essential perceptible features, which determine the consumer’s judgment. Overproduction of free radicals including reactive oxygen species (ROS) disturbs the mitochondrial function in living cells. During high-temperature mitochondrial substrate oxidation and electron transport chain (ETC) activity increases. This increased activity results in excessive production of superoxide that oxidizes protein and lipid contents in muscle tissues. By oxidizing protein and lipid, ROS spoils the nutritive quality of chicken meat. High ambient temperature is one of the major contributing factors that enhance oxidative stress. Poultry feed with anti-oxidant supplementation and innovative processing techniques can help the poultry industry to overcome oxidative stress.

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Almost a decade ago, the sudden rise of breast muscle defects in fast-growing commercial broiler breeds challenged the broiler production industry and meat scientists to address the issue of these novel muscle abnormalities. After that, a widespread hypothesis showing a correlation between high muscle yield and incidence of these muscle myopathies got much acceptance from the research community. Increased muscle hypertrophy and unbalanced growth of connective tissues lead to an inadequate blood supply that ultimately causes hypoxia in muscle fibers. Reduced blood vascular density in muscle fibers induces oxidative stress and mitochondrial dysfunction, leading to muscle fibrosis, lipidosis and myodegeneration. Along with physical changes, the myopathic muscles exhibit poor sensory properties, abnormal texture properties and a low nutritional profile. As these myopathies alter meat’s physical appearance, they have a negative impact on customer’s behavior and preference. A better production environment with proper dietary supplementation with balanced breeding strategies can minimize the incidence of muscle myopathies in broiler chicken. This review aims to address the underlying mechanism behind these myopathies and their impact on poultry meat quality, including nutritional value and consumer behavior. It describes the link between genetic and non-genetic elements influencing myopathies, along with the strategies to minimize the occurrence of breast muscle myopathies.

Previously, circRNAs considered splicing errors during transcription, but recent studies uncovered that circRNA is a new group of noncoding RNAs. CircRNAs are produced through back splicing of pre mRNA and have more stability than linear RNA due to its closed loop structure. Numerous studies have unveiled the regulatory functions of circRNA in various biological mechanisms. Current literature has observed that circRNAs regulate the myogenesis of skeletal muscles through sponging miRNAs or acting as competitive endogenous RNA (CeRNA). Apart from myogenesis, it also regulates the functioning of different proteins at the molecular level and plays a key role during translation or protein encoding. All these facts have opened a new arena of research regarding the regulation of gene expression. This study aims to discuss the research advancements and new developments in the regulatory functions of circRNAs, including the development of skeletal muscle. This study also intends to discuss some newly discovered circRNAs involved in skeletal muscle development, especially in chicken and cattle.