Abstract
Background:
The quality of drinking water affects antibiotic bioavailability in the broiler chickens.

Aim:
The current study highlights on the influence of water quality on the bioavailability of antibiotics in broiler. The water quality was determined based on the Zn, Cu, Fe, Mn, and Pb levels.

Methods:
The animal study involved 234 chickens divided into 6 broad groups. Chickens in subgroup A received water containing the maximum level of metals (low dose) while chickens in subgroup B received water containing 5× of the A subgroup (high dose). The control group was given bottled. The effects of metals in drinking water on the bioavailability of oxytetracycline and amoxicillin were evaluated for the various groups. Different concentrations of the metals cause different responses to the bioavailability of the antibiotics at different times.

Results:
Low levels of Zn, Pb, Mn, and Cu, and high levels of Zn and Pb resulted in a significant (p< 0.001) increase in the Cmax of oxytetracycline after 2 hours of treatment as compared with the control group. Low levels of Zn, Pb, Mn, Fe, and Cu, and high levels of Zn, Pb, and Mn also resulted in a significant (p< 0.001) increase in the Cmax of oxytetracycline after 4 hours of treatment as compared with the control group. Similarly, the water treated with low levels of Fe and Cu, and high levels of Zn and Fe resulted in a significant (p< 0.001) increase in the Cmax of amoxicillin after 2 hours of treatment as compared with the control group.

Conclusion:
The concentrations of studied heavy metalssignificantly affect the bioavailability of the antibiotics and alter their effectiveness.

Key words: Antibiotics; Bioavailability; Broilers; Poultry; Saudi Arabia.