Effect of natural zeolite in diets with or without protein reduction on the performance, carcass and organ yield, and litter quality of broilers

Ammonia emissions from poultry litter represent a major environmental and production challenge in modern broiler systems and are strongly influenced by dietary crude protein levels and nitrogen utilization efficiency. Natural zeolites, particularly clinoptilolite, have been proposed as nutritional strategies to mitigate ammonia volatilization; however, their effects on broiler performance remain inconsistent, especially when combined with protein reduction. This study evaluated the effects of natural zeolite (Celpec®) inclusion at 0, 1.0, 2.0, and 3.0% in diets formulated with two crude protein levels (recommended or reduced by 3%) on growth performance, carcass and organ yield, and litter quality of broiler chickens. A total of 720 one-day-old male Ross broilers were allocated in a completely randomized design in a 4 × 2 factorial arrangement, with six replicates of 15 birds each. Growth performance (feed intake, body weight gain, and feed conversion ratio), carcass yield and commercial cuts, relative weight of digestive organs, and litter quality (in natura ammonia concentration and microbiological evaluation) were assessed. Data were analyzed using analysis of variance, regression analysis, and Dunnett's test (P < 0.05). No significant interaction between zeolite inclusion level and dietary crude protein was observed. Zeolite inclusion above 1% impaired growth performance, particularly in diets with reduced crude protein. Crude protein reduction alone negatively affected performance from 35 d of age onward. Zeolite inclusion did not reduce Escherichia coli counts in the litter. However, inclusion of up to 1% zeolite reduced ammonia concentration in the litter without compromising growth performance or carcass yield, regardless of dietary protein level. These findings indicate that dietary inclusion of clinoptilolite at 1% is an effective strategy to reduce ammonia emissions from broiler litter without impairing performance or carcass yield, provided that diets are formulated with adequate protein and amino acid balance, whereas higher inclusion levels or protein restriction compromise productive responses.