Context Animal feed production systems have been suffering from a shortage of feedstuffs because of competition for these resources with human food consumption. The use of by-products can increase efficiency and circularity in production chains, reducing this competition. Aims This study investigated the impacts of Paullinia cupana peel meal (PCPM) on the growth performance, meat quality, and haematological and serum biochemical parameters of slow-growing broilers. Methods Two hundred and forty slow-growing male Label Rouge broilers were distributed in a completely randomised experimental design. The treatments consisted of five inclusion levels of PCPM (0%, 2.5%, 5.0%, 7.5%, and 10%) in the diets, with four replicates of 12 birds each. Growth performance data, and haematological and serum biochemical parameters were monitored. Twelve broilers per treatment were slaughtered for meat-quality analysis. Key results In the starter stage, there was a significant increase (P < 0.05) in feed intake and weight gain with and increasing inclusion level of PCPM in the diet. However, this effect diminished in the final stage. Even with a reduction (P < 0.05) in feed intake during the final stage, the broilers showed an increase (P < 0.05) in weight gain and improvement (P < 0.05) in feed efficiency in the cumulative performance. Broilers fed diet with a higher inclusion level of PCPM had lower (P < 0.05) concentrations of erythrocytes and blood triglycerides, as well as a decreased haematocrit percentage. However, these broilers exhibited higher (P < 0.05) results for mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration. Broilers fed diets with a higher inclusion level of PCPM were heavier (P < 0.05) at slaughter, with higher (P < 0.05) carcass yield, greater (P < 0.05) liver, gizzard, and heart weight, increased breast, drumstick, and thigh yields, and higher moisture and lipid contents in the breast. Conclusions The high inclusion levels of PCPM in diets for slow-growing broilers positively affect growth performance, meat quality, and yields of valuable cuts, although they increase moisture and decrease protein in breast meat, affecting some blood parameters. Implications This study showed the potential advantages of using PCPM as an alternative food in diets for slow-growing broilers to improve the productivity and health of a sustainable livestock.
