FROM MUSCLE TO MEAT: MORPHO-FUNCTIONAL FOUNDATIONS FOR APPLICATIVE ASPECTS.

The transformation of muscle into meat is a biologically complex mechanism with deep implications for animal physiology, the meat industry, and food science. Understanding the morpho-functional foundations of this process -including structural, cellular, and molecular characteristics of muscle tissue- provides a basis for optimizing meat quality parameters, such as texture, flavour, and shelf life. This thesis investigates three essential aspects of muscle biology, focusing on i) myogenesis -muscle development and growth-; ii) muscle morpho-functional characteristics; iii) future-oriented advancements in cell-based meat production. In livestock, particularly among native breeds, myogenesis is influenced by distinct genetic traits that also enhance the animals' resilience to environmental challenges. The interaction between animal’s genetic background and external factors, such as seasonal temperature variations, affects the regulation of muscle cell proliferation and differentiation. By examining breed-specific and seasonal variations in myogenesis, we can develop targeted strategies to enhance growth, health, and meat quality across the year, addressing physiological and environmental demands. Understanding muscle development and its influencing factors at birth is crucial for optimizing growth outcomes and improving the efficiency of swine production. Hence, the first study aimed to assess the effects of the genetic background and birth seasons on muscle development at birth. It focused on muscles Longissimus dorsi (LD) and Semimembranosus (SM) of newborn piglets of two different breeds, the local Nero di Lomellina (NL) and the commercial hybrid Landrace x Duroc (CH), born in two different seasons (winter and summer). Moreover, muscle morpho-functional characterization may provide insights into how breed, environment, and dietary intervention shape meat quality. Variations in muscle fiber size, distribution, and biochemical metabolism occur among different animal breeds and under various environmental conditions. Temperature influences muscle fiber characteristics, which in turn impacts growth rates and meat quality. Similarly, dietary inputs modulate muscle morphology, affecting fiber development, hypertrophy, and metabolic capacity. By analysing these histological variations across breeds, seasonal temperatures, and dietary supplementations, we gain essential insights into optimizing meat production while maintaining quality under different conditions. Therefore, the next two studies investigated the influence of breed (NL and CH) and rearing cycle (December to October, September to July) on pig muscles (LD and SM) at slaughter. They aimed to evaluate the combined effect of these factors on muscle morphological traits and meat physicochemical parameters, thereby offering a more comprehensive characterization of meat quality. The fourth study focused on rabbit meat and addressed dietary supplementation: it aimed to investigate the effect of bovine colostrum dietary administration on the quality of muscle SM, particularly regarding the metabolic shift in muscle fibers. Finally, given the steady increase in global meat demand, it is pivotal to develop alternative products. Cell-based meat offers a sustainable and ethical solution, addressing key challenges such as environmental impact, resource scarcity, and animal welfare. Consequently, the final study explored the most innovative approaches in cultured meat research, focusing on the recent challenge of co-culturing different cell types on 3D supports to properly replicate the heterogeneous structure and three-dimensional architecture of muscle tissue. In this context, understanding in vivo muscle development and morpho-functional aspects are critical for improving cell-based meat by replicating the taste, texture, and nutritional qualities of conventional meat in vitro. By translating knowledge of muscle biology and morphology from live animals to cultured settings, researchers can refine tissue engineering techniques. A comprehensive understanding of muscle biology will be essential for overcoming challenges in cellular agriculture, paving the way towards sustainable meat alternatives to satisfy future global demand.