Nutritional consequences of intensive broiler farming: a focus on amino acid profile and protein digestibility

Meat is widely recognized as a valuable source of high-quality protein and essential amino acids, unlike most plant-based foods, which require combination to achieve a complete amino acid profile. Among animal products, broiler chicken breast is particularly rich in protein. However, the genetic selection for fast growth in modern broiler lines has led to the emergence of muscle abnormalities such as wooden breast, white striping, and spaghetti meat, which are associated with deteriorated meat sensory, technological and nutritional quality. Within the framework of the H2020 INTAQT project, we assessed the quality of chicken breast meat from 32 farms representative of six poultry production systems in Europe. These systems vary by growth rate, slaughter age and weight, and access to outdoor areas: Indoor_Fast_Heavy, Indoor_Fast, Outdoor_Fast_Heavy, Outdoor_Medium, and Outdoor_Slow—the latter including Label Rouge and male layer hybrids. In addition to standard sensory, technological, nutritional, and sanitary assessments, our study focused on protein digestibility and amino acid composition. Breast meat samples were minced, cooked to 70 °C core temperature, and subjected to in vitro digestion. Protein content was measured before and after digestion; small and large peptides were quantified via the Kjeldahl method, and free amino acids analyzed using HPLC. The lowest protein content and digestibility were found in meat from the Indoor_Fast_Heavy system, characterized by the highest daily weight gain (>60 g/day) and slaughter weights of 2.6–2.8 kg. Essential amino acid content was higher in meat from broiler raised in system Outdoor_Medium (56 days) and up to 80 days than those raised in system Indoor_Fast (35 days). Leucine levels, crucial for muscle protein synthesis, were significantly higher in all systems compared to Indoor_Fast_Heavy. Arginine, histidine, and tryptophan release during digestion was also consistently lower in samples from the most intensive system. These findings underscore the impact of production systems on the nutritional quality of chicken meat, particularly in terms of amino acid profiles, and raise concerns about the impact of intensive farming practices based on fast-growing genotypes. The dataset will be further enriched with complementary quality indicators, including the incidence of breast muscle myopathies, to investigate potential links between meat nutritional value and the prevalence of these muscle disorders.