Bacterial contamination of semen has become an important contributor to the reduced shelf life of insemination doses in the poultry industry, which is why antibiotics (ATBs) are an important component of semen extenders. Due to a global rise in antimicrobial resistance, the aim of this study was to assess the efficiency of selected commercially available semen extenders to prevent possible bacterial contamination of rooster ejaculates. Two selected extenders free from or containing 31.2 μg/mL kanamycin (KAN) were used to process semen samples from 63 healthy Lohmann Brown roosters. Phosphate-buffered saline without ATBs was used as a control. The extended samples were stored at 4 °C for 24 h. Sperm motility, viability, mitochondrial activity, DNA integrity and the oxidative profile of each extended sample were assessed following 2 h and 24 h of storage. Furthermore, selective media were used to quantify the bacterial load and specific bacterial species were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The results indicate that semen extenders enriched with KAN ensured a significantly higher preservation of sperm quality in comparison to their KAN-free counterparts. Bacterial load was significantly decreased in diluents supplemented with ATBs (p ≤ 0.001); however, KAN alone was not effective enough to eradicate all bacteria since several Escherichia coli, Enterococcus faecalis, Enterococcus faecium and Micrococcus luteus were retrieved from samples extended in KAN-supplemented commercial extenders. As such, we may suggest that more focus should be devoted to the selection of an optimal combination and dose of antibiotics for poultry extenders, which should be accompanied by a more frequent bacteriological screening of native as well as extended poultry semen.

AgroBioTech Research Centre Slovak University of Agriculture in Nitra Tr A Hlinku 2 94976 Nitra Slovakia

Department of Bioenergetics Food Analysis and Microbiology Institute of Food Technology and Nutrition University of Rzeszow Cwiklinskiej 1 35 601 Rzeszow Poland

Department of Neuroscience 2nd Faculty of Medicine Charles University 5 Úvalu 84 15006 Prague Czech Republic

Institute of Applied Biology Faculty of Biotechnology and Food Sciences Slovak University of Agriculture in Nitra Tr A Hlinku 2 94976 Nitra Slovakia

Institute of Biotechnology Faculty of Biotechnology and Food Sciences Slovak University of Agriculture in Nitra Tr A Hlinku 2 94976 Nitra Slovakia

Institute of Fruit Science Viticulture and Enology Faculty of Horticulture and Landscape Engineering Slovak University of Agriculture Tr A Hlinku 2 94976 Nitra Slovakia

References provided by Crossref.org