Oregano extract (Origanum vulgare) in female broiler chickens of free-range strain raised in the Western Amazon

ABSTRACT This study aimed to evaluate the effect of oregano extract added commercial diets on zootechnical performance parameters, carcass yield, immunological conditions, morphometry, and intestinal pH for free-range broiler chickens raised under sanitary challenge conditions. Three hundred chicks strain ‘Heavy red’ were used distributed in a completely randomized experimental design with five treatments six replications, totaling 30 units, each consisting 10 birds. The were: T1: Basal diet without (OE); T2: OE (150 mg/kg); T3: (250 T4: (350 T5: (450 mg/kg). There was significant feed intake, weight gain, conversion, efficiency, heterophil/lymphocyte ratio (H/L), morphometry. No differences observed viability, pH, lymphoid organs, gizzard, heart, intestine. Oregano influenced liver yield abdominal fat broilers. Overall, inclusion at level 350 mg/kg provided better results.