Determination of virginiamycin in feeds

Area of Science:

• Analytical Chemistry
• Animal Nutrition
• Microbiology

Background:

• Virginiamycin is an important antibiotic used in animal feed for growth promotion and disease prevention.
• Accurate quantification of virginiamycin in feed is crucial for ensuring correct dosage and efficacy.
• Existing analytical methods may face challenges with complex feed matrices and potential interferences.

Purpose of the Study:

• To develop and validate a reliable method for extracting and quantifying virginiamycin in various animal feed types.
• To assess the recovery rates and precision of the developed method across different feed matrices and virginiamycin concentrations.
• To evaluate the interference of common feed additives on virginiamycin determination.

Main Methods:

• Extraction of virginiamycin using ethanol-pH 2.5 phosphate buffer.
• Preparation of sample dilutions and standard dose-response lines using ethanol pH 6 phosphate buffer.
• Microbiological assay using the test organism Sarcina lutea.
• Analysis of poultry and swine feed samples fortified with known virginiamycin concentrations.

Main Results:

• High recovery rates (88.8--108.9%) for virginiamycin were achieved in poultry and swine feeds at concentrations ranging from 4.54 to 90.8 g/ton.
• The coefficient of variation was lower for high-potency feeds (100 g/ton) compared to low-potency feeds (10 g/ton).
• Amprolium, roxarsone, and monensin did not significantly interfere with the assay, while lasalocid showed a slight positive bias at 10 times the virginiamycin concentration.

Conclusions:

• The developed ethanol-phosphate buffer extraction method is effective for quantifying virginiamycin in animal feed.
• The assay provides accurate and reliable results with good recovery and acceptable precision.
• The method is robust against common feed additives, making it suitable for routine analysis in animal feed quality control.