Microbiota of bovine milk, teat skin, and teat canal: Similarity and variation due to sampling technique and milk fraction

摘要

The aim of this study was to evaluate the effect ofsampling technique and milk fraction on bovine milkmicrobiota data and to compare the microbiota in milkto microbiota on the teat end and in the teat canal.Representative milk samples are highly important forassessment of bacteriological findings and microbiotain milk. Samples were obtained from 5 healthy lactatingdairy cows at udder quarter level during 1 milking.Swab samples from the teat end and teat canal,and milk samples collected using different techniquesand in different milk fractions were included. Milk wascollected by hand stripping and through a teat canalcannula before and after machine milking, through atrans–teat wall needle aspirate after milking, and fromudder quarter composite milk. The microbiota of thesamples was analyzed with sequencing of the V1–V3region of the 16S rRNA gene. In addition, somatic cellcounts and bacterial cultivability were analyzed in themilk samples. Microbiota data were analyzed usingmultivariate methods, and differences between sampleswere tested using analysis of similarity (ANOSIM).Differences between samples were further explored viaindividual studies of the 10 most abundant genera. Themicrobiota on the teat end, in the teat canal, and inudder quarter composite milk, collected using a milkingmachine, differed in composition from the microbiota inmilk collected directly from the udder quarter. No differencesin milk microbiota composition were detectedbetween hand-stripped milk samples, milk samplestaken through a teat canal cannula, or milk samplestaken as a trans–teat wall needle aspirate before or aftermilking. We conclude that for aseptic milk samplescollected directly from the lactating udder quarter,sampling technique or milk fraction has minor effect onthe microbiota composition.