56 Effect of Florfenicol on Hematology, Cardiac Enzymes and its Residues in Broiler Chickens by HPLC Ahmed A. Said 1 , Sameh M. El-Nabtity 1 , Abdulla A.M. Selim 2 , Mai A. Fadel 2* 1 Pharmacology Department, Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt 2 Animal Health Research Institute, Dokki, Giza, Egypt Article History: Received: 5/3/2016 Received in revised form: 30/5/2016 Accepted: 20/6/2016 Abstract The current study was conducted on multiple oral doses (40 mg/kg for 3 successive days) of florfenicol (FF) to determine its effect on some hematological parameters, cardiac enzymes and its residues in blood and tissues (liver, muscles and kidneys) of broiler chickens. Seventy broiler chickens were used and divided into two groups, each consisted of 35 birds. The first group was left as a control, while the second was given FF for 3 successive days. The FF residues in tissues were determined using reversed phase-high performance liquid chromatography (RP-HPLC) with ultraviolet (UV) detector at 223 nm. Results indicated a widespread distribution of FF in most of the tested tissues. All tissue samples were considered FF free on the 9 th day after the last oral dose except liver. Florfenicol administration elicited a significant decrease in all blood parameters (hemoglobin concentration (Hb), red blood cell count (RBCs), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC) and lymphocytes) from 1 st up to 7 th day except packed cell volume (PCV) which showed no significant change on 1 st day but decreased on 3 rd , 5 th and 7 th day after stopping medication. Moreover, monocytopenia was observed on the 5 th and 7 th day and white blood cells (WBCs) showed the same effect on the 5 th day, while heterophiles revealed highly elevation. All cardiac enzymes (aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase MB (CK-MB) and Troponin I) were highly elevated. In conclusion, broiler chicken meat can be consumed safely after 9 days post FF treatment. Keywords: Florfenicol, Broiler chicken, HPLC Residues, Hematological parameters, Cardiac enzymes Introduction Florfenicol (FF) is a bacteriostatic antibiotic that inhibits protein synthesis by binding ribosomal subunits of susceptible bacteria, consequently inhibiting the peptidyl transferase and then preventing the transfer of amino acids to growing peptide chains and subsequent protein formation [1]. Florfenicol has a fluorine atom instead of the hydroxyl group located at C-3 in the structure of chloramphenicol and thiamphenicol. It is used for treating bovine respiratory disease, in addition, FF may be considered a bactericidal against some Mannheimia (Pasteurella) hemolytica and Pasteurella multocida when it is administered to achieve minimum inhibitory concentrations (MICs) [2]. The minimum bactericidal concentrations (MBCs) are very close to the MICs. Following the administration of FF (30 mg/kg BW) in broiler chickens via intravenous (IV), intramuscular (IM) and oral routes, the highest drug residues were found in the kidneys, bile, lungs, muscles, intestine, heart, liver, spleen and plasma, while the lowest concentrations were found in brain, bone marrow and fat [3]. No FF residues were detected in tissues and plasma after 72 h except in the bile which disappeared after 96 h [3]. The microbiological Acceptable Daily Intake (ADI) is 3 μg/kg BW, i.e. 180 μg per person and a toxicological ADI of 10 μg/kg BW, i.e. 600 μg per person had previously been reported by the Committee for Veterinary Medicinal Products [4]. The presence of FF residues in broiler meat and Zagazig Veterinary Journal Volume 44, Number 1, p. 56-66, June, 2016 ©Faculty of Veterinary Medicine, Zagazig University, 44511, Egypt DOI: 10.21608/zvjz.2016.7832. *Corresponding author e-mail: (dr.mai87@yahoo.com), Animal Health Research Institute, Dokki, Giza, Egypt.