Mai A. Fadel1*, Maha S. Abd El-Hafeez1, Mahmoud Mohamed Abd El-Moneam2

Abstract | Antibiotics administration to chicks is common for metaphylaxis or treatment of suspected infections. Tylvalosin is a macrolide antibiotic with an antiviral activity. Through this study, we highlighted tylvalosin role on broiler’s immune response after Newcastle disease virus (NDV) vaccination when administrated alone or together with a probiotic bacterium Lactobacillus acidophilus. Immune response was measured by challenge, hemagglutination inhibition (HI) tests and interleukin 8 (IL-8) level. Moreover, the study evaluated pharmacokinetics and tissue residues of tylvalosin by a modified validated HPLC method when administrated alone or with ND vaccination and/or L. acidophilus intake. The results illustrated that both NDV vaccinated group (V) and NDV vaccinated group treated with tylvalosin (VT) showed full (100%) protection in response to challenge with very virulent NDV. The non-vaccinated groups (T, L) showed 66.6% and 40%, respectively. Besides, (VT) group had no significant change in HI titer and IL-8 concentration if compared with (V) group. Pharmacokinetic parameters of (VT) group revealed significant decrease in (area under curve AUC (0-t, 0-info) with Cmax) and significant increase in (t0.5β, V/F, CL/F and Tmax than group treated with tylvalosin alone (T) and vaccinated group treated with tylvalosin and L. acidophilus (VTL). The highest residues were detected in lung and liver and the lowest in muscle. The recommended withdrawal time in VT group was 4 days but in groups (T & VTL) was 5 days. Finally, tylvalosin has a synergistic action with NDV vaccine as it has no negative effect on the immunity to NDV vaccine which enhances significantly tylvalosin pharmacokinetics and residues. L. acidophilus didn’t cause any significant amelioration for poultry.

Keywords | Tylvalosin- NDV- Lactobacillus acidophilus - Kinetics-residues.