Climate conditions associated with the occurrence of antimicrobial and macrocyclic lactone residues in bulk tank milk

Abstract

The present study aimed to identify the climate condition parameters that are associated with the occurrence of antimicrobial and macrocyclic lactone residues in bulk tank milk using a multivariate principal components analysis (PCA). A total of 132 raw milk samples were collected at dairy farms in Minas Gerais State in Brazil and analyzed for 35 analytes, comprising macrocyclic lactones and antibacterials, using liquid chromatography coupled with mass spectrometry in tandem mode spectrometry. Of the 132 samples, 34 (25.76%) bulk tank milk samples were positive for at least one analyte. PCA showed that antimicrobial residues in bulk tank milk occurred less frequently on days with a higher average temperature, maximum temperature and temperature-humidity index. In contrast, relative humidity was inversely associated with antimicrobial residues in raw milk. The PCA showed that daily milk production was also related to macrocyclic lactone residues, while rainfall showed an inverse association. Thus, some climate conditions, such as average temperature, maximum temperature and temperature-humidity index, can predict the moments with lower risk of occurrence of antimicrobial residues in bulk tank milk, in contrast to relative humidity. Furthermore, the risk of macrocyclic lactone residues in bulk tank milk was higher in months with less rainfall.Keywords: anthelmintic, antibiotic, veterinary drug, seasonality, raw milk RESUMO O presente trabalho objetivou identificar fatores climáticos associados à ocorrência de resíduos de antimicrobianos e lactonas macrocíclicas em amostras de leite de tanque por análise multivariada de componentes principais (ACP). Para o presente trabalho, 132 amostras de leite cru foram coletadas em fazendas leiteiras localizadas no estado de Minas Gerais (Brasil