Abstract
The present study was conducted to investigate the effect of antibiotics alternatives as prebiotic, organic acid and antibiotic supplementation to the broiler chicks on their protective effect against artificial infection with ciprofloxacin marked E.coli O25, growth performance, survival rate, immunity, serum biochemistry and response to NDV. Three-hundred and fifty-day-old broiler chicks were divided into 7 equal groups, 50 chicks each, group 1 was kept as control. Chicks of group 2 was infected orally with 0.2ml of E.coli O25 containing 1x108 viable organism /ml in phosphate buffered saline (PBS) and kept as infected control group. Chicks of group 3 was received organic acid (butyric) in water (2ml/liter). Chicks of group 4 was received prebiotic (Hydrostar) in water (1ml/2liter). Chicks of group 5 was received antibiotic (neomycin) in water (1gm/liter) for 5 successive days. Chicks of group 6 was received prebiotic (Hydrostar) and antibiotic (neomycin). Chicks of group 7 was received organic acid (butyric) and antibiotic (neomycin). At 15 days of age chickens of groups 3- 4-5-6 and 7 were orally inoculated with o.2 ml of phosphate buffered saline (PBS) containing 1 x 108 viable organism /ml of E coli O25 by the same does of group 2. Our results showed that the birds received organic acid (butyric acid) (G3) and prebiotic (Hydrostar) (G4) showed more favorable clinical signs, mortality rate, P.M. lesions, recovery rate, bacterial re-isolation results, growth performance and improved immune response to NDV. A decrease in the mean values of serum ALT and AST and creatinine levels and increase in mean values of albumin, globulin and antioxidant enzymes (SOD and CAT) were recorded that may provide evidence for the hepato and renoprotective effects of organic acid (butyric acid) and prebiotic (Hydrostar). It could be concluded that prebiotic (Hydrostar) and organic acid (butyric acid) can be used as antibiotics alternatives due to their high efficacy in (growth performance, antibacterial and positive impact on both liver, kidney functions and antioxidant enzymes). This study highly recommends the use of Hydrostar and butyric acid as a prophylactic agents in dealing with E. coli infection in chicken however, its concurrent administration with neomycin in treatment of such case revealed the most favorable outcomes.

Key words: antibiotic alternatives, prebiotic, organic acid, E. coli, broiler chicks, growth performance, serum biochemistry