Screening for penicillin plasma residues in cattle by enzyme-linked immunosorbent assay

Abstract

In this Study, we established a rapid prediction test for the detection of the cattle with violative tissue residues of penicillins. The recommended therapeutic doses of two penicillins, ampicillin (withdrawal time, 6 days) and amoxicillin (withdrawal time, 14 days), were administered to two groups of 10 cattle each. Blood was sampled and tested before drug administration and during the withdrawal period. The concentration of penicillins in plasma, determined by a semi-quantitative ELISA, was compared to that of internal standard (4ppb as penicillin G). The absorbance ratio of internal standard to sample (B/Bs) was introduced as an index to determine whether drug residues in cattle tissues are negative or positive. That means B/Bs ratio lower than 1 was considered residue positive and that higher than 1 negative. All 10 plasma samples from non-treated cattle showed negative results for both penicillins. Both penicillins were detected in plasma samples of cattle treated Until the 3rd day of withdrawal period. The present study lias shown that the semi-quantitative ELISA could be easily adapted for prediction of screening plasma residues for penicillin antibiotics (ampicillin and amoxicillin) in live cattle.