Supplementation of broiler diets with propolis and oregano oil and its effect on production parameters, leukocytes, metabolites and breast meat antioxidant stability

Abstract

Propolis and oregano oil are natural substances used in various food industry applications. An evaluation was done of the effects of oregano oil (A) and propolis (P) on production parameters, leukocytes, blood chemistry and meat antioxidant stability in broilers. Animals (n= 480) were randomly allocated to four treatments with four replicates of 30 animals each. Four additive levels (mg/k feed) were tested: C (control)= 0; P= 100 mg propolis; A= 100 mg oregano oil; and AP= 50 mg P + 50 mg A. At 42 d breast meat lipid oxidative stability was estimated based on malondialdehyde (MDA) content. The oregano oil contained 43.47% thymol and 29.16 % carvacrol, while the propolis contained 5.6 mg flavonoids, 840 µg phenols and 138 µg Trolox® equivalents (antioxidant stability) per gram. Feed intake, weight gain, feed conversion and mortality were unaffected by the dietary additives. At 3 wk, blood eosinophil levels increased in treatment AP (P≤0.05), and at 6 wk triglycerides had increased in treatment A (P≤0.05). Meat lipid oxidative stability decreased in the AP treatment (P≤0.05). Neither oregano oil nor propolis improved production parameters, although they can stimulate immune response. When added to low-fat broiler diets they can increase blood triglycerides and in combination they compromise breast meat lipid oxidative stability.