The Evaluation of Therapeutic Doses of Erythromycin on the Main Hematological Parameters of Broiler Chickens

Monitoring of hematologic profile in a group of broiler chickens (n = 33) was the basis for the evaluation of tolerance and the influence of various doses of erythromycin thiocyanate. The investigations required the formation of the 3 homogeneous groups (2 experimental and 1 control), each consisting of 11 individuals, 12-19 days of age and weighing around 500 g, kept and fed under identical conditions. The individuals from the experimental groups were treated for 7 consecutive days with therapeutic (10 mg/individual/day) and double (20 mg/individual/day) doses of erythromycin. During the experiment were performed two sets of hematological investigations (pre-and post-treatment) on blood samples collected (on heparin) from the three groups of chickens, consisting in determining: the total number of erythrocytes and leukocytes, packed cell volume (PCV) hemoglobin concentration (Hb), mean erythrocyte constants, white blood cell counts and leucogram. The results were interpreted statistically and compared with reference values. Global analysis of the developments registered in the investigated physiological parameters of the groups of broiler chickens revealed mean values variations from one group to another, falling within physiological limits of the species and category, or with slight deviations from some references, respectively the intervals established in the control group. Comparative developments of hematological parameters pre-and post-treatment outlined a normal profile for the investigated category of broiler chickens, indicating a good tolerance of therapeutic and double doses of erythromycin thiocyanate with no negative effects on electrolyte balance and erythrocyte homeostasis, erythropoiesis and general erythrocyte functions. An overview of the determined leukocyte parameters data, outlined specific aspects of leukocyte configuration with a good defensive potential, for the group treated with therapeutic dose and also for the one treated with the double dose of erythromycin thiocyanate. Statistical analysis of the obtained data showed significant differences (p <0.05) only in case of the control group, consisting of a decrease in the percentage of heterophiles from (43.182.71 to 38.366.50) and an increase in the percentage of lymphocytes (from 37.364.20 to 42.646.65), due to individual cases of slight heteropenia and/or lymphocytosis. The results of the clinical and hematological monitoring of the health status, have led to the identification of no potential risks associated with doubling the dose of erythromycin thiocyanate. The investigated doses of 10 or 20 mg/individual/day, for a period of 7 consecutive days, lacked immediate or delayed adverse reactions respectively signs of immunosuppression.