Evaluation of boldenone as a growth promoter in broilers: safety and meat quality aspects

The object of this study was to evaluate the safety and meat quality criteria in broilers following intramuscular injection of boldenone. Twenty-four broiler chicks, divided into two groups, were used in the present study. Boldenone was injected intramuscularly at a single-dose level of 5 mg/kg body weight into 12 broiler chicks at 2 weeks old; the other 12 chicks were injected with sesame oil and kept as controls. Blood samples were collected from the wing and metatarsal veins after 1, 2, and 3 weeks through the experimental course for hematological and clinic-chemical safety parameters. On the last day, chicks were humanely sacrificed and livers and kidneys were removed for histopathological examination. Breast muscles were also removed to assess meat-quality parameters. Boldenone signifi-cantly (p < 0.05) increased total erythrocytic count and hemoglobin and hematocrit values, while mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration indices decreased. Leukogram showed leukopenia, lymphopenia, and granulocytosis (p < 0.05) as compared to control. Hepatorenal biomarkers, including alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, urea, and creatinine were significantly (p < 0.05) higher than the corresponding control values. Additionally, boldenone significantly (p < 0.05) increased metabolic markers, including total protein, globulins, cholesterol, triacylglycerols, and glucose, with parallel decreases in albumin and albumin/ globulin ratio. Degenerative changes were recorded in liver and kidney tissues from chicks treated with boldenone. Muscle samples exhibited raised pH values and higher microbial counts as compared to the corresponding control. These data may discourage the use of boldenone as a growth promoter in broilers due to safety and meat quality reasons.