Pilot study--parenteral treatment of recently acquired subclinical mastitis during lactation

OBJECTIVE: To conduct a pilot study to investigate the effect of parenteral antibiotic treatment with penethamate hydriodide on recently acquired sub-clinical mastitis. DESIGN: Sixty-nine cows from five Western Victorian dairy farms were enrolled in a pilot trial. Cows that had an Individual Cow Cell Count (ICCC) of greater than 250,000 cells per mL in their milk at their first or second herd test were enrolled in the trial if they were in their first lactation, or if they had a history of ICCCs below 250,000 cells per mL at all herd tests during the previous lactation. These criteria were used in an effort to exclude cows with chronic subclinical mastitis and include cows with recently acquired subclinical mastitis. PROCEDURE: Cows were divided into control and treatment groups on the basis of having an odd or even ear tag number. The treatment group was treated with penethamate hydriodide shortly after the first or second herd test; the control group was left untreated. The ICCCs of subsequent herd tests were recorded for the remainder of lactation. RESULTS: In 58% of the treatment group, and 25% of the control group, all subsequent ICCCs for that lactation were less than 250,000 cells per mL (p < 0.05). If only first and second lactation cows were considered, 72% of the treatment group, and 11% of the control group, had subsequent ICCCs less than 250,000 cells per mL (p < 0.05). CONCLUSION: An ICCC of greater than 250,000 cells per mL is a good predictor for more high ICCCs at subsequent herd tests. This effect was significantly altered in our trial by treatment with penethamate hydriodide at or near the first or second herd test. Whilst in general treatment of high ICCC cows during lactation is considered to be unrewarding, this pilot study suggests that treatment of cows and heifers appropriately selected on the basis of a previous history of low ICCCs can lead to sustained reductions in cell counts. These results support the case for further study into this area.     

Therapeutic effects of systemic or intramammary antimicrobial treatment of bovine subclinical mastitis during lactation

The short- and long-term treatment efficacy of administrating penicillin for bovine subclinical mastitis during lactation when using intramuscular (IM; 9.5 mg [15,000 IU]/kg bodyweight of benzyl penicillin potassium) injections twice daily for 5 days, or intramammary (IMM; 0.3g [300,000 IU] penethamate hydroiodide) administration once daily for 5 days was compared with a control group receiving no treatment. One hundred and twenty-six cows met the inclusion criteria, which were lack of clinical symptoms, no recent treatment with antimicrobials, and findings of penicillin-sensitive Staphylococcus aureus, Streptococcus dysgalactiae, or Streptococcus uberis in combination with an inflammatory reaction. At follow-up 42-58 days after treatment, the proportion of cows negative for the original infection was significantly higher in IM and IMM groups compared to controls, but the difference between antimicrobial treatment groups was not significant. The udder quarter milk somatic cell count (SCC) was significantly lower at follow-up in IM and IMM groups than in controls, but milk production did not differ between treatments. The culling rate during the 10-month period following treatment was significantly higher in the group treated with IMM penicillin than in the other two groups, but the risk of new mastitis treatments within 10 months did not differ between the three groups. The cure rate was significantly affected by lactation number (lower in older cows), breed (lower in the Swedish Holstein breed), pathogen (lower for S. aureus), and pre-treatment SCC (higher for above average SCC). In conclusion, beneficial long-term effects of antimicrobial treatment during lactation of subclinical mastitis caused by S. aureus, Str. dysgalactiae or Str. uberis were not found in the present study.     

Trematode infections in pregnant ewes can predispose to mastitis during the subsequent lactation period

Objective was to investigate if trematode infections predispose ewes to mastitis and/or metritis. We used 80 trematode-infected ewes: primigravidae in group P-A and multigravidae in M-A remained untreated, primigravidae in P-B and multigravidae in M-B were drenched with netobimin and multigravidae in M-C were given rafoxanide. We collected faecal samples for parasitological examination, blood samples for β-hydroxybutyrate concentration measurement and uterine content, teat duct material and milk samples for bacteriological examination. We found significant differences in blood β-hydroxybutyrate concentrations between M-A, M-B and M-C during pregnancy (P ? 0.002). We did not observe significant differences between groups regarding development of metritis (P > 0.83). We found that for M-A, M-B and M-C ewes, respectively, median time to first case of mastitis was 5.75, 21 and 6.75 days after lambing (P = 0.003) and incidence risk of mastitis was 0.308, 0.069 and 0.222 (P = 0.047). We postulate that trematode infections predispose ewes to mastitis; perhaps, increased β-hydroxybutyrate blood concentrations adversely affect mammary cellular defences. This is the first report associating parasitic infections with mastitis in sheep.     

Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows

The aim of this study was to evaluate the effect of postpartum mastitis between first calving and subsequent conception on production and reproduction performance as well as culling of Holstein cows. A data set of 9,183 first lactation cows was used. Results showed that the first cumulative 100?days' milk production and the milk yield standardized to 305?days were affected by the interval from calving to first mastitis (P??0.05). Calving year, calving difficulty score, and cumulative first 60?days milk production had significant impacts on mastitis risk (P?相似文献   

Treatment of mastitis

Extract

Since penicillin came into common use, mastitis is no longer as serious a problem as it was formerly. It is still an important disease, however, and questions on methods of treatment are often asked. This paper discusses recent work in this field.     

Cost estimation of heifer mastitis in early lactation by stochastic modelling

Heifer mastitis, reflected by an elevated somatic cell count (SCC) in early lactation (SCCel), results in a decreased milk production, a higher risk for subclinical and clinical mastitis during lactation, and an elevated culling hazard. The aims of this study were to calculate the costs of heifer mastitis defined as an elevated SCC in early lactation, and to show the variation of these costs in the Dutch/Belgian dairy sector. A stochastic model, in which the variation and uncertainty of heifer mastitis are taken into the account, was developed with input data from literature and expertise. Costs were estimated, using default values. The mean costs for an elevated SCCel that cured were on average euro 13/heifer present on a farm (range: euro 0-118), for an elevated SCC at calving proceeding in subclinical mastitis on average euro 5/heifer present on a farm (range: euro 0-euro 82), and for a clinical heifer mastitis case associated with an elevated SCC after calving on average euro 270. On average this results in euro 13/heifer present on a farm (range: euro 0-137). Combined, these three cost aspects result in a total cost of on average euro 31/heifer present on a farm (range: euro 0-220). The large variation in the costs is very important regarding farm management and farm support. The difference in costs reflects also the difference in room for investment. When the costs that can be prevented are estimated at farm level, these data can be of help in setting goals in herd health advice and farm management.     

Antimicrobial susceptibility of mastitis pathogens from first lactation and older cows

Increasing antimicrobial resistance has become a serious concern worldwide and antimicrobial use in animal agriculture is currently under scrutiny. Mastitis is the most common reason for antibiotic use in dairy herds and thus, antimicrobial resistance of mastitis pathogens has received recent attention. The purpose of this study was to describe and compare antimicrobial susceptibility of mastitis pathogens isolated at calving from first lactation and older cows. A total of 202 bacteria were isolated from intramammary infections (IMIs) within 3 days after calving over a 16-month study period in the Krauss Dairy Research Herd at the Ohio Agricultural Research and Development Center (OARDC) in Wooster, OH. Of these IMIs, 78% were caused by coagulase-negative staphylococci (CNS). Forty-four percent of them were resistant to at least one antibiotic. Most resistance was observed against penicillin, 39% of the isolates from older cows and 26% from first lactation cows being resistant to penicillin (P > 0.05). Also MIC90 for penicillin was higher among isolates from older cows. On the other hand, resistance to tetracycline was more common and MIC90 higher among isolates from first lactation cows than from older cows. Differences in the proportions of resistant isolates between first lactation and older cows were not statistically significant, though. The resistance patterns of the CNS isolated during the study are concordant with antimicrobial usage in the study herd. This is in agreement with the generally accepted notion that selection pressure from the use of antibiotics is a main factor in development of antibiotic resistance.     

The prophylactic effect of a teat sealer on bovine mastitis during the dry period and the following lactation

AIM: To determine the prophylactic efficacy of a teat sealer, administered at drying off, in reducing new intramammary infections in the dry period and the following lactation. METHODS: A total of 528 cows with late lactation somatic cell counts <2 00,000 cells/ml was identified in three commercial herds. Of these, bacteriological examination showed 482 cows were uninfected in all four quarters and 46 were infected in only one quarter. At drying off, uninfected quarters were randomly allocated to the following treatments: no infusion (negative controls), infusion with a bismuth subnitrate based teat sealer, infusion with teat sealer + antibiotic, or infusion with a cephalonium-based dry cow antibiotic (positive control). New infections were identified during the dry period by periodic udder palpations and at calving by bacteriological culture. RESULTS: All three infused treatments reduced the incidence of new intramammary infections due to Streptococcus uberis, both during the dry period and at calving, by about 90% (p <0.01). The majority of the infections were due to Streptococcus uberis. For all treatments, a 50% lower incidence of clinical mastitis over the first 5 months of the ensuing lactation was reported by farmers. X-ray imaging of 19 teats showed that the teat sealer material was retained, at least in part, in the lower teat sinus over about 100 days of the dry period. CONCLUSIONS: Closure of the teat canal from day one of the dry period as achieved by the teat sealer was as effective in reducing new dry period infections as the infusion of a long-acting dry cow antibiotic formulation. The lower incidence of new infections in the ensuing lactation among the infused quarters implies that fewer subclinical infections persisted from the dry period. Use of teat sealers at drying off appears to offer the same prophylactic efficacy as the dry cow antibiotic approach.     

The use of a hand-held conductivity meter for the diagnosis of subclinical mastitis in dairy cows during late lactation

AIM: To evaluate the accuracy of a hand-held electrical conductivity meter for the detection of subclinical mastitis in an Australian dairy herd in late lactation. METHODS: A hand-held conductivity meter was evaluated during late lactation in a herd of dairy cows that had a high prevalence of Streptococcus agalactiae and Staphylococcus aureus infection. The ability of the conductivity meter to accurately discriminate between uninfected quarters and those infected with major pathogens was assessed, using bacteriology as the definitive test for infection status. Milk samples for bacteriology, and electrical conductivity measurements, were collected from 233 quarters from 59 cows. The ability of the device to identify infected and uninfected cows was also assessed. Sensitivity and specificity were calculated for a range of threshold values, using absolute values, the range of quarter values within a cow and the ratio of quarter values within a cow. RESULTS: Electrical conductivity was higher in infected quarters than uninfected quarters, but the degree of overlap between the populations was substantial, even when quarters were assessed as case-control pairs from the same cow. Use of the device according to the manufacturer's recommendations for diagnostic criteria of mastitic quarters had a sensitivity of 51% and a specificity of 71%. The ability of the device to correctly diagnose the infection status of cows was dependent on both the analytical method and the threshold value used. Applying the manufacturer's recommended criteria to the diagnosis of the status of cows, the sensitivity of the test was 91% and the specificity 17%. CONCLUSION: The variability between individual quarters and between cows in this study was such that the use of this device to measure the conductivity of milk was not a reliable method by which to diagnose subclinical mastitis in cows in late lactation. CLINICAL RELEVANCE: Interpretation of results from handheld conductivity meters when used for the diagnosis of subclinical mastitis in dairy cows needs to be made with care. In some circumstances the results obtained do not accurately reflect the bacteriological status of either individual quarters, or cows.     

Treatment of subclinical mastitis.

Topics addressed in this article include applied pharmacology of the bovine mammary gland, principles of antibiotic sensitivity testing, mechanisms of antimicrobial resistance, causes of treatment failures, diagnostic considerations, and therapy of specific subclinical mastitis syndromes. Recent research concerning systemic therapy of subclinical mastitis is highlighted and critically reviewed. Limitations of antibiotic sensitivity testing are discussed. The lack of proven, efficacious therapy for many subclinical mastitis syndromes is emphasized.     

Prevalence of clinical mastitis in 38 Waikato dairy herds in early lactation

AIM: To determine the prevalence of clinical mastitis in spring-calving dairy herds in the Waikato Region of New Zealand and to identify factors associated with variation in the prevalence of clinical mastitis between herds. METHOD: A total of 799 quarters from 595 dairy cows from 38 dairy herds were diagnosed by herd owners as having clinical mastitis between 8 July and 21 August 1997. Quarters diagnosed with clinical mastitis were sampled for bacterial culture and somatic cell count, and the presence of clots in the milk and the presence of udder oedema were assessed by a technician or veterinarian. RESULTS: Clinical mastitis was diagnosed in an average (+/-s.e.m.) of 9.9% (+/-0.8%, range 0.9-21.4%) of calved cows within the herds. Bacteria were not cultured from an average of 12.4 % (+/- 2.0%, range 0.0-45.5%) of cows and 22.3% (+/- 2.4%, range 0.0-54.0%) of quarters diagnosed as having clinical mastitis. There were significant differences between herds in the proportion of cows diagnosed with mastitis and in the proportion of clinical mastitis cases from which bacteria were not cultured. A decreased prevalence of clinical mastitis (p<0.001) was associated with an increased percentage of the herd treated with dry cow antibiotics. An increased prevalence of clinical mastitis (p<0.0001) was associated with both an increased percentage of cows treated in the previous season with lactating cow antibiotics and an increased percentage of heifers in the herd. Herds that were fed supplements before or during lactation had a higher prevalence of clinical mastitis than herds that were not fed supplements (p<0.001). An increased proportion of quarters diagnosed with clinical mastitis that did not culture bacteria was associated with an increased prevalence of clinical mastitis (p<0.001). The proportion of quarters that the technician or veterinarian found with evidence of clinical mastitis (i.e. a somatic cell count >500,000 cells/ml and the presence of either clots or udder oedema) within a herd was inversely related to the proportion of quarters within a herd from which no bacteria were isolated. CONCLUSION: There was a large variation in the prevalence of clinical mastitis and in the proportion of clinical quarters from which no bacteria were grown between herds. Management factors such as the use of dry cow therapy, feeding regimes and heifer replacement rates all affected the prevalence of clinical mastitis. Herd owners appear to differ in the sensitivity and specificity of their diagnosis of clinical mastitis, with bacteria not isolated from up to 50% of quarters diagnosed with clinical mastitis in some herds. Improvements in the specificity of herd owner diagnosis of clinical mastitis may reduce the use of antibiotics for mastitis during lactation and hence may reduce the risk of antibiotic contamination of milk supplied for human consumption.     

Changes in various metabolic parameters in blood and milk during experimental Escherichia coli mastitis for primiparous Holstein dairy cows during early lactation

Background:The objective of this study was to characterize the changes in various metabolic parameters in blood and milk during IMI challenge with Escherichia coli(E.coli) for dairy cows during early lactation.Thirty,healthy primiparous Holstein cows were infused(h = 0) with-20-40 cfu of live ? coli into one front mammary quarter at ~4-6wk in lactation.Daily feed intake and milk yield were recorded.At-12,0,3,6,12,18,24,36,48,60,72,96,108,120,132,144,156,168,180 and 192 h relative to challenge rectal temperatures were recorded and quarter foremilk was collected for analysis of shedding of E.coli.Composite milk samples were collected at-180,-132,-84,-36,-12,12,24,36,48,60,72,84,96,132 and 180 h relative to challenge(h = 0) and analyzed for lactate dehydrogenase(LDH),somatic cell count,fat,protein,lactose,citrate,beta-hydroxybutyrate(BHBA),free glucose(fglu),and glucose-6-phosphate(G6P).Blood was collected at-12,0,3,6,12,18,24,36,60,72,84,132 and 180 h relative to challenge and analyzed for plasma non-esterified fatty acids(NEFA),BHBA and glucose concentration.A generalized linear mixed model was used to determine the effect of IMI challenge on metabolic responses of cows during early lactation.Results:By 12 h,E.coli was recovered from challenged quarters and shedding continued through 72 h.Rectal temperature peaked by 12 h post-challenge and returned to pre-challenge values by 36 h post-IMI challenge.Daily feed intake and milk yield decreased(P 0.05) by 1 and 2 d,respectively,after mastitis challenge.Plasma BHBA decreased(12 h;P 0.05) from 0.96 ± 1.1 at 0 h to 0.57 ±0.64 mmol/L by 18 h whereas concentration of plasma NEFA(18 h) and glucose(24 h) were significantly greater,11 and 27%,respectively,after challenge.In milk,fglu,lactose,citrate,fat and protein yield were lower whereas yield of BHBA and G6 P were higher after challenge when compared to pre-challenge values.Conclusions:Changes in metabolites in blood and milk were most likely associated with drops in feed intake and milk yield.However,the early rise in plasma NEFA may also signify enhanced adipose tissue lipolysis.Lower concentrations of plasma BHBA may be attributed to an increase transfer into milk after IMI.Decreases in both milk lactose yield and%after challenge may be partly attributed to reduced conversion of fglu to lactose.Rises in G6 P yield and concentration in milk after challenge(24 h) may signify increased conversion of fglu to G6 P.Results identify changes in various metabolic parameters in blood and milk after IMI challenge with E.coli in dairy cows that may partly explain the partitioning of nutrients and changes in milk components after IMI for cows during early lactation.     

Changes in various metabolic parameters in blood and milk during experimental Escherichia coli mastitis for primiparous Holstein dairy cows during early lactation

Background

The objective of this study was to characterize the changes in various metabolic parameters in blood and milk during IMI challenge with Escherichia coli (E. coli) for dairy cows during early lactation. Thirty, healthy primiparous Holstein cows were infused (h = 0) with ~20-40 cfu of live E. coli into one front mammary quarter at ~4-6 wk in lactation. Daily feed intake and milk yield were recorded. At –12, 0, 3, 6, 12, 18, 24, 36, 48, 60, 72, 96, 108, 120, 132, 144, 156, 168, 180 and 192 h relative to challenge rectal temperatures were recorded and quarter foremilk was collected for analysis of shedding of E. coli. Composite milk samples were collected at -180, -132, -84, -36, -12, 12, 24, 36, 48, 60, 72, 84, 96, 132 and 180 h relative to challenge (h = 0) and analyzed for lactate dehydrogenase (LDH), somatic cell count, fat, protein, lactose, citrate, beta-hydroxybutyrate (BHBA), free glucose (fglu), and glucose-6-phosphate (G6P). Blood was collected at -12, 0, 3, 6, 12, 18, 24, 36, 60, 72, 84, 132 and 180 h relative to challenge and analyzed for plasma non-esterified fatty acids (NEFA), BHBA and glucose concentration. A generalized linear mixed model was used to determine the effect of IMI challenge on metabolic responses of cows during early lactation.

Results

By 12 h, E. coli was recovered from challenged quarters and shedding continued through 72 h. Rectal temperature peaked by 12 h post-challenge and returned to pre-challenge values by 36 h post-IMI challenge. Daily feed intake and milk yield decreased (P <0.05) by 1 and 2 d, respectively, after mastitis challenge. Plasma BHBA decreased (12 h; P <0.05) from 0.96 ± 1.1 at 0 h to 0.57 ± 0.64 mmol/L by 18 h whereas concentration of plasma NEFA (18 h) and glucose (24 h) were significantly greater, 11 and 27%, respectively, after challenge. In milk, fglu, lactose, citrate, fat and protein yield were lower whereas yield of BHBA and G6P were higher after challenge when compared to pre-challenge values.

Conclusions

Changes in metabolites in blood and milk were most likely associated with drops in feed intake and milk yield. However, the early rise in plasma NEFA may also signify enhanced adipose tissue lipolysis. Lower concentrations of plasma BHBA may be attributed to an increase transfer into milk after IMI. Decreases in both milk lactose yield and % after challenge may be partly attributed to reduced conversion of fglu to lactose. Rises in G6P yield and concentration in milk after challenge (24 h) may signify increased conversion of fglu to G6P. Results identify changes in various metabolic parameters in blood and milk after IMI challenge with E. coli in dairy cows that may partly explain the partitioning of nutrients and changes in milk components after IMI for cows during early lactation.     

Diarrhoea during lactation lostridia

1引言 梭状芽孢杆菌属包括许多种类的大的杆状孢子厌氧菌,这些菌能产生许多具有很强致病性的病菌毒素.因此梭状芽孢杆菌疫苗常含有灭活的毒素,以抵抗毒素的作用.所幸的是,许多这类毒素都是高分子量的蛋白质,因此具有很好的免疫原性,能诱导高水平的抗体.