The pharmacokinetic aspects of cephradine were studied after intravenous (IV), intramuscular (IM), subcutaneous (SC) and oral administration of a single dose of 50 mg kg-1 b.wt. in chickens. Tissue distribution and residues of cephradine after repeated oral administration for 5 consecutive days were also estimated. After IV injection of cephradine in a dose of 50 mg kg-1 b.wt., the serum concentration time curves were best described by a two compartment-open model. The drug was rapidly distributed with a distribution half-life (t0.5(α)) of 0.120 h and apparent volume of distribution (Vdss) was 2.187 L kg-1. The drug was rapidly eliminated with a half-life of elimination (t0.5(β)) of 1.047 h and the body clearance (ClB) was 2.35 L kg-1 h-1. The drug was rapidly absorbed after IM, SC and oral administration as indicated by short half-lives of absorption (t0.5(ab)) of 0.154, 0.364 and 0.65 h., respectively. While the elimination half-lives (t0.5(el)) and systemic bioavailabilities were 0.859, 2.652, 1.74 h and 59.386, 84.5, 97.97 %, respectively. Repeated oral administration of cephradine (50 mg kg-1 b.wt twice daily) for 5 consecutive days caused no change in serum enzyme activities of ALT and AST but induced a significant increase in serum uric acid concentration at 72 to 120 hours post administration.

Three vaccination regimes based on Clostridium perfringens (C. perfringens) type A, C or combined AC toxoids were evaluated to detect if toxoid vaccines can prevent necrtotic enteritis (NE) caused by clostridial infection in broilers. The vaccines were administered two times at two weeks interval, then the birds were challenged with virulent strains of C. perfringens type A, C or combined AC. Blood samples were taken after both first and second vaccination doses as well as after challenge. Evaluating parameters included clinical signs, gross intestinal lesions, hemogram [red blood cell count (RBCs), packed cell volume (PCV), hemoglobin (Hb), total leukocytic count (TLC) and differential leukocytic count],serum biochemical assays [total protein (TP), albumin (Alb), globulin (Glob), albumin globulin ratio (A/G), serum activities of alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP) and uric acid (UA) values] and ELISA test for detecting serum antibody titers. Results revealed that affected birds showed marked depression, anorexia, reluctance to move, ruffled feathers and diarrhea. Numbers of chickens with intestinal lesions in immunized challenged groups were greatly fewer than the infected non immunized ones. There was an increase in RBCs, PCV and Hb. TLC decreased in infected non immunized birds and increased in vaccinated ones. Heterophils were increased in infected groups while, lymphocytes decreased. Prominent lymphocytosis was observed in immunized birds. Results of biochemical assays showed that there was a significant increase in TP, Alb, Glob, ALP, ALT, AST and UA and decrease in A/G. Results of ELISA test showed that there was a significant increase in antibody titer after immunization paricularly after the second dose of vaccination. The combined AC toxoid provided the greater antibody titer and best protection followed by toxoid A and finally toxoid C. We concluded that results provide an evidence that immunization of broilers with toxoid vaccines paricularly the combined type AC is safe, welltolerated and can protect broiler chickens against NE after the second booster dose of the vaccine.