| 1. |
- Dahlberg, Josef, et al.
(författare)
-
Microbiota data from low biomass milk samples is markedly affected by laboratory and reagent contamination
- 2019
-
Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- Discoveries of bacterial communities in environments that previously have been described as sterile have in recent years radically challenged the view of these environments. In this study we aimed to use 16S rRNA sequencing to describe the composition and temporal stability of the bacterial microbiota in bovine milk from healthy udder quarters, an environment previously believed to be sterile. Sequencing of the 16S rRNA gene is a technique commonly used to describe bacterial composition and diversity in various environments. With the increased use of 16S rRNA gene sequencing, awareness of methodological pitfalls such as biases and contamination has increased although not in equal amount. Evaluation of the composition and temporal stability of the microbiota in 288 milk samples was largely hampered by background contamination, despite careful and aseptic sample processing. Sequencing of no template control samples, positive control samples, with defined levels of bacteria, and 288 milk samples with various levels of bacterial growth, revealed that the data was influenced by contaminating taxa, primarily Methylobacterium. We observed an increasing impact of contamination with decreasing microbial biomass where the contaminating taxa became dominant in samples with less than 10 4 bacterial cells per mL. By applying a contamination filtration on the sequence data, the amount of sequences was substantially reduced but only a minor impact on number of identified taxa and by culture known endogenous taxa was observed. This suggests that data filtration can be useful for identifying biologically relevant associations in milk microbiota data.
|
|
| 2. |
|
|
| 3. |
- Dahlberg, Josef, et al.
(författare)
-
Microbiota of bovine milk, teat skin, and teat canal: Similarity and variation due to sampling technique and milk fraction
- 2020
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 103, s. 7322-7330
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to evaluate the effect of sampling technique and milk fraction on bovine milk microbiota data and to compare the microbiota in milk to microbiota on the teat end and in the teat canal. Representative milk samples are highly important for assessment of bacteriological findings and microbiota in milk. Samples were obtained from 5 healthy lactating dairy cows at udder quarter level during 1 milking. Swab samples from the teat. end and teat canal, and milk samples collected using different techniques and in different milk fractions were included. Milk was collected by hand stripping and through a teat canal cannula before and after machine milking, through a trans-teat wall needle aspirate after milking, and from udder quarter composite milk. The microbiota of the samples was analyzed with sequencing of the V1-V3 region of the 16S rRNA gene. In addition, somatic cell counts and bacterial cultivability were analyzed in the milk samples. Microbiota data were analyzed using multivariate methods, and differences between samples were tested using analysis of similarity (ANOSIM). Differences between samples were further explored via individual studies of the 10 most abundant genera. The microbiota on the teat end, in the teat canal, and in udder quarter composite milk, collected using a milking machine, differed in composition from the microbiota in milk collected directly from the udder quarter. No differences in milk microbiota composition were detected between hand-stripped milk samples, milk samples taken through a teat canal cannula, or milk samples taken as a trans-teat wall needle aspirate before or after milking. We conclude that for aseptic milk samples collected directly from the lactating udder quarter, sampling technique or milk fraction has minor effect on the microbiota composition.
|
|
| 4. |
- Duse, Anna, et al.
(författare)
-
Occurrence and Spread of Quinolone-Resistant Escherichia coli on Dairy Farms
- 2016
-
Ingår i: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 82, s. 3765-3773
-
Tidskriftsartikel (refereegranskat)abstract
- Quinolone-resistant Escherichia coli (QREC) is common in feces from young calves, but the prevalence and genetic diversity of QREC in groups of cattle of other ages and the farm environment are unknown. The aims of the study were to obtain knowledge about the occurrence of QREC on dairy farms, the genetic diversity of QREC within and between farms, and how these relate to the number of purchased animals and geographic distances between farms. We analyzed the within-sample prevalence of QREC in individual fecal samples from preweaned dairy calves and postpartum cows and in environmental samples from 23 Swedish dairy farms. The genetic diversity of the QREC isolates on 10 of these farms was assessed. In general, QREC was more prevalent in the dairy farm environment and in postpartum cows if QREC was commonly found in calves than if QREC was rare in calves. In particular, we found more QREC organisms in feed and water troughs and in environments that may come into contact with young calves. Thus, the results suggest that QREC circulates between cattle and the farm environment and that calves are important for the maintenance of QREC. Some genotypes of QREC were widespread both within and between farms, indicating that QREC has spread within the farms and likely also between farms, possibly through purchased animals. Farms that had purchased many animals over the years had greater within-farm diversity than farms with more closed animal populations. Finally, animals on more closely located farms were more likely to share the same genotype than animals on farms located far apart.
|
|
| 5. |
- Duse, Anna, et al.
(författare)
-
Risk factors for antimicrobial resistance in fecal Escherichia coli from preweaned dairy calves
- 2015
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 98, s. 500-516
-
Tidskriftsartikel (refereegranskat)abstract
- The primary objective of this study was to investigate calf and farm factors associated with antimicrobial-resistant Escherichia coli in the feces of preweaned dairy calves in Sweden. In particular, we investigated the effects of feeding calves colostrum and milk from cows treated with antimicrobials. The secondary objective was to describe the prevalence of resistant E. coli in feces of preweaned dairy calves in Sweden. Fecal samples from 3 calves, aged 7 to 28 d, from 243 farms were analyzed for the within-sample prevalence of E. coli resistant to nalidixic acid, streptomycin, and cefotaxime using selective agars supplemented with antimicrobials. In addition, resistance to 12 antimicrobials was tested in one randomly selected E. coli isolate per calf. Information was collected from the farmers via questionnaires regarding the use of colostrum and milk from cows treated with antimicrobials as calf feed and other uses of antimicrobials in the herd. Multivariable zero-inflated negative binomial and logistic regression models were used to assess the effect of various risk factors for shedding of resistant E. coli. Escherichia coli resistant to streptomycin, nalidixic acid, or cefotaxime were isolated from 90, 49, and 11% of the calves, respectively. Resistance to at least one antimicrobial was found in a random isolate of E. coli from 48% of the calves. Feeding colostrum from cows treated with antimicrobials at drying off did not affect the prevalence of resistant E. coli. In contrast, feeding milk from cows treated with antimicrobials during lactation resulted in significantly more nalidixic acid- and streptomycin-resistant E. coli than when such milk was discarded; no significant effect was seen for other resistance traits. Furthermore, an interaction was found between feeding milk from cows treated with antimicrobials and use of fluoroquinolones in cows. In general, the prevalence of resistance was lower for older calves and calves on small farms. Other factors that were associated with the shedding of resistant E. coli were administration of oral dihydrostreptomycin to calves, administration of systemic tetracycline and ceftiofur to cows and calves, housing of the calves, predominant breed of the herd, and geographic location of the farm. The presence of resistant E. coli in calves was clearly due to multiple factors, but minimizing the feeding of milk from cows treated with antimicrobials during lactation should lower the prevalence of resistant E. coli in the gastrointestinal tract of the calves.
|
|
| 6. |
- Duse, Anna, et al.
(författare)
-
Risk factors for quinolone-resistant Escherichia coli in feces from preweaned dairy calves and postpartum dairy cows
- 2015
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 98, s. 6387-6398
-
Tidskriftsartikel (refereegranskat)abstract
- Quinolone resistance may emerge in gut bacteria (e.g., in Escherichia coli) of animals. Such bacteria could cause infections in the animal itself or be transmitted to humans via the food chain. Quinolone resistance is also observed in fecal E. coli of healthy dairy cattle, but the prevalence varies between farms, not solely as a result of varying degree of fluoroquinolone exposure. The objective of this study was to identify risk factors for the fecal shedding of quinolone-resistant E. coli (QREC) from dairy calves and postpartum cows. Rectal swabs from 15 preweaned calves and 5 postpartum cows per farm were collected on 23 Swedish dairy farms to determine the prevalence of QREC. Risk factors for the shedding of QREC were investigated using multivariable statistical models. Quinolone-resistant E. coli were found on all but one farm. Factors associated with QREC shedding by calves were being younger than 18 d, being fed milk from cows treated with antimicrobials, recent use of fluoroquinolones in the herd, carriage of QREC by postpartum cows, and using the calving area never or rarely as a sick pen compared with often. Factors associated with QREC shedding by cows were calving in group pens or freestalls compared with single pens or tiestalls, purchasing cattle, sharing animal transports with other farmers, and poor farm hygiene. Proper biosecurity and improved hygiene, as well as minimizing fluoroquinolone exposure and waste milk feeding, may be important factors to reduce the burden of QREC on dairy farms.
|
|
| 7. |
|
|
| 8. |
- Persson Waller, Karin, et al.
(författare)
-
Udder health in beef cows and its association with calf growth
- 2014
-
Ingår i: Acta Veterinaria Scandinavica. - : Springer Science and Business Media LLC. - 0044-605X .- 1751-0147. ; 56
-
Tidskriftsartikel (refereegranskat)abstract
- Conclusions: Subclinical mastitis and IMI, but not blind quarters, were common in beef cows, but the prevalence varied markedly between herds. Most IMI were caused by staphylococci and more than 95% of those were sensitive to penicillin. Cows with large funnel-shaped teats or pendulous udder after calving, and cows with blind quarters were at risk of having subclinical mastitis and/or IMI. Poor hygiene was also a risk factor for udder health problems. No significant associations were found between udder health and calf weaning weight. More studies on risk factors are warranted to improve advisory services on awareness and prevention of mastitis in beef cows.
|
|
| 9. |
- Persson, Ylva, et al.
(författare)
-
Associations between Staphylococcus aureus intramammary infections and somatic cell counts in dairy goat herds
- 2015
-
Ingår i: Small Ruminant Research. - : Elsevier BV. - 0921-4488. ; 133, s. 62-66
-
Tidskriftsartikel (refereegranskat)abstract
- Staphylococcus (S.) aureus is an important pathogen in cheese producing dairy goat farms. The aim of this study was to investigate whether somatic cell count (SCC) and PCR analysis of S. aureus in bulk tank milk (BTM), and/or SCC in udder half milk samples could indicate intramammary infection (IMI) with S. aureus. Milk samples (n = 1042) were collected from lactating udder halves of 521 lactating does from 16 herds in mid to late lactation. From the same herds 29 BTM samples were collected. Udder half samples were cultured on blood agar plates and the SCC was measured by California mastitis test (CMT) and DeLaval cell counter (DCC-SCC). Bulk tank milk samples were analysed by PCR for presence of S. aureus and by DCC-SCC. In 15% of the udder halves bacteria was found and of these 80% had CNS and 8% had S. aureus. Udder halves infected with S. aureus had significantly higher DCC-SCC and CMT than udder halves not infected (P<0.0001) and udder halves infected with CNS (P<0.01) and higher DCC-SCC than udder halves infected with other bacteria (P=0.0004). There was a significantly higher risk for a doe to have S. aureus IMI in at least one udder half if the CMT was high in one udder half and low in one udder half (P=0.04) compared to does with low CMT in both udder halves. Significant associations between BTMSCC, S. aureus positive BTM, or IMI with S. aureus could not be found. However, 6 out of 8 herds with S. aureus IMI were PCR positive for S. aureus at least once. A difference in CMT between milk from udder halves within a doe can be used as an indicator for S. aureus IMI at goat level. On udder half level, milk SCC, measured with DCC or CMT, can be used to detect S. aureus IMI. (C) 2015 Elsevier B.V. All rights reserved.
|
|
| 10. |
- Persson, Ylva, et al.
(författare)
-
Intramammary infections and somatic cell counts in meat and pelt producing ewes with clinically healthy udders
- 2017
-
Ingår i: Small Ruminant Research. - : Elsevier BV. - 0921-4488. ; 156, s. 66-72
-
Tidskriftsartikel (refereegranskat)abstract
- Mastitis in sheep is common and is important both from an economic and from a welfare point of view. It can be either clinical or subclinical, bacterial or, more seldom, lentiviral. There are no data on the national prevalence of subclinical mastitis (SCM) or intramammary infection (IMI), and causative pathogens, in ewes in Sweden.Diagnosis of SCM and/or IMI is based on inflammatory indicators, measured in milk and additional bacteriology. Somatic cell count (SCC) is the most widely used indicator of SCM and/or IMI and can be measured either directly or indirectly with e.g. California Mastitis Test (CMT). However, the use of SCC as an indicator for mastitis and/or IMI in ewes is not fully evaluated, especially not in meat- and pelt producing herds. The aim of this study was therefore to investigate the prevalence of IMI and bacterial panorama in ewes with clinically healthy udders, in meat- and pelt producing herds in Sweden. Moreover, we wanted to define a cut-off for SCC and CMT for detecting ewes with IMI that would be suitable for use under field conditions.Udder half milk samples (n = 2134) were collected at weaning and lambing from meat- and pelt producing ewes (n = 773), in 22 farms in Sweden. Only clinically healthy animals were included in the study. Milk samples were analysed for bacteriology and SCC and were given a CMT score.Intramammary infection was found in 30% of the ewes and in 14% of the udder half milk samples. No bacteria were found in 74% of the milk samples, and mixed flora was found in 12% of the samples. Among the 287 milk samples where IMI was identified, coagulase negative staphylococci (CoNS) were most prevalent (58%) followed by Staphylococcus (S.) aureus (9%) and Mannheimia (M.) haemolytica (6%). Among the 165 CoNS findings S. simulans was the most common (26%), followed by S. warren, S. equorum, S. xylosus, S. haemolyticus and S. chromogenes. A CMT score of >= 3 and a SCC of 500,000 cells/ml at weaning or CMT score 3 and a SCC of 400,000 cells/ml after lambing gave the highest possible Se at the same time as the highest possible Sp for identifying udder halves with IMI and may be used for screening for IMI in Swedish meet and pelt producing herds.To conclude, one third of Swedish meat- and pelt producing ewes without clinical signs in the udder had IMI M one or both udder halves at weaning and or after lambing, and CoNS was the most common bacterial finding. A high SCC 400,000-500,000 cells/nil) was associated with IMI and a difference in having a high (CMT 3-5) or low (CMT 1-2) between udder halves can be used as an indicator of IMI under field conditions.
|
|
