PERFORMANCE, PHYSIOLOGICAL AND MARKET ASPECTS OF FAST-AND SLOW-GROWING BROILERS: A COMPARATIVE STUDY

Brazilian poultry production has undergone intense modernization in recent decades, driven by genetic selection for high productive performance, particularly in fast-growing broilers. Simultaneously, the increasing demand for production systems aligned with animal welfare and sustainability has promoted the expansion of slow-growing strains targeted at differentiated market niches. This study presents a comparative analysis of the productive and physiological differences between fast- and slow-growing broiler chickens, discussing their impacts on growth performance, carcass yield, meat quality, and physiological integrity. Fast-growing strains exhibit higher daily weight gain, improved feed conversion, and greater breast yield, reaching slaughter weight in a shorter period. However, these birds show a greater predisposition to metabolic, locomotor, and oxidative disorders as a consequence of intense selection for rapid growth and high muscle deposition. In contrast, slow-growing broilers demonstrate more gradual growth, lower feed efficiency, and longer rearing periods, but exhibit better locomotor performance, greater rusticity, improved adaptation to alternative production systems, and differentiated meat quality attributes, such as more intense coloration and firmer texture. Physiologically, notable differences are observed in muscle fiber composition, metabolic profiles, and responses to oxidative stress, reflecting distinct biological strategies among genotypes. It is concluded that both production models meet specific market demands, and the choice of strain depends on production objectives, management conditions, and the consumer segment to be served.