Sulfamethazine blood/tissue correlation study in swine

Area of Science:

• Veterinary Pharmacology
• Food Safety
• Animal Science

Background:

• Sulfamethazine is an antibiotic used in swine production.
• Regulatory limits exist for sulfamethazine residues in edible animal tissues.
• Accurate prediction of tissue residues is crucial for food safety and compliance.

Purpose of the Study:

• To correlate serum sulfamethazine concentrations with liver and muscle concentrations at slaughter.
• To evaluate the necessity of complete feed withdrawal for meeting regulatory limits.
• To assess the predictive value of serum sulfamethazine for tissue residue levels.

Main Methods:

• Feeding study with 70 market-weight hogs.
• Medicated feeds containing varying sulfamethazine concentrations were administered.
• Serum, liver, and muscle samples were analyzed at slaughter.

Main Results:

• Complete sulfamethazine withdrawal was not required to achieve liver concentrations below 0.1 mg/kg.
• Feed concentrations up to 2 g/metric ton in withdrawal feeds did not exceed liver tolerance.
• Serum sulfamethazine concentrations >0.45 mg/L predicted liver concentrations >0.10 mg/kg with 100% accuracy.

Conclusions:

• Partial withdrawal of sulfamethazine may be sufficient to meet regulatory liver tolerances.
• Serum sulfamethazine concentration is a reliable indicator of tissue residue levels.
• This data can inform optimized withdrawal protocols for swine.