The presence of antibiotic residues in raw milk samples obtained after the withdrawal period and other quality parameters in relation to selected factors

Abstract

The aim of this study was to compare the results of the presence of antibiotic (AB) residues in the milk of dairy cows treated with ABs – during the withdrawal period (WP) and after the WP obtained by various screening tests (Delvotest T, Twinsensor BT020, and Eclipse 50), to evaluate the presence of AB residues with regard to selected factors (indication for AB administration, AB group, and a number of antimicrobial substances) and to assess selected parameters of milk quality (fat, crude protein, lactose, somatic cell count (SCC), and fat/protein ratio (F/P)). A total of 234 samples was analysed for these parameters. The presence of AB residues in milk samples obtained from dairy cows during the WP and after the WP was detected. A statistically significant difference in the percentage of positive milk samples obtained during the WP and after the WP was found only for Delvotest T (p = 0.0060). For milk samples obtained during the WP and after the WP, the highest positivity was detected when tested with Twinsensor BT020, followed by Delvotest T and Eclipse 50. After the WP, the incidence of positive results differed significantly by indication for AB administration only when tested with Delvotest T (p = 0.0212), which showed the highest positivity for mastitis (37.0%). The fat content (p = 0.0060), F/P (p = 0.0007), and SCC (p = 0.0015) differed significantly depending on the indication. The fat content (p = 0.0093), F/P (p = 0.0470), and SCC (p = 0.0175) also differed significantly depending on the administered AB group. The highest potential risk in terms of the presence of AB residues was found in the milk samples obtained from dairy cows after treatment for mastitis.