Relationship between teat morphological traits and subclinical mastitis in Frieswal dairy cows

The present study was aimed to investigate the relationship between selected morphological traits of teat and subclinical mastitis (SCM) in Frieswal crossbred dairy cows. A total of 1040 quarters from 261 lactating cows were evaluated for teat shape (bottle/fleshy/collapsed/conical/normal/pencil and short), teat-end shape (dished/flat/funnel/pocketed/pointed and rounded), teat orientation (aligned/misaligned) and teat position (front and rear; left-sided and right-sided). Each udder quarter was screened with California Mastitis Test (CMT) for the purpose of defining quarter health status. Data were analysed using Chi-square test and multivariable logistic regression procedure. An overall prevalence of SCM (CMT positive) at quarter level was 30.6%. Most of the teats had normal or cylindrical shapes (48%), dished teat-ends (40.7%), and aligned (central or squared) in orientation (65%). At bivariable level, significant association of SCM with teat shape, teat position, teat orientation, parity, and stage of lactation was observed (P < 0.05 to P < 0.001). Teat-end shapes showed some association with SCM (P = 0.07). Results of multivariable analysis showed that pencil-shaped teats were least associated with SCM (P < 0.05) as compared to other teat shapes. Prevalence of SCM was also higher in rear teats (P = 0.015), misaligned teats (P = 0.01), and cows in second or higher parities (P < 0.01) and late stage of lactation (P < 0.001). The results of the present study indicate that selected morphological traits of teat are associated with SCM in Frieswal crossbred cows; therefore, selection towards desirable morphological traits could help reduce mastitis in this breed.     

Treatment of persistent intramammary infections with Streptococcus uberis in dairy cows

A survey was conducted of the prevalence of environmental pathogens, especially Streptococcus uberis, as causes of clinical mastitis in dairy cows. The response of intramammary infections with S uberis to conventional treatment was monitored by taking milk samples for bacteriology and somatic cell counting seven, 14 and 21 days after the treatment. The results showed that 51 per cent of the infections failed to respond, and the odds of cases failing to respond was significantly increased when the individual quarter somatic cell count seven days after the treatment was greater than 201,000 cells/ml. Ninety-six per cent of the suspected S uberis isolates identified by culture were confirmed as S uberis by using the api 20 Strep system. Restriction endonuclease fingerprinting was used to type the strains of S uberis isolated from 75 milk samples from 32 cows. Analysis showed that 96 per cent of the cases of S uberis that failed to respond to conventional treatment were persistent infections with one strain rather than reinfections with different strains. The persistent cases of S uberis were treated further with an extended course of intramammary preparations containing either procaine penicillin with dihydrostreptomycin or cefquinome. There was no significant difference between the cure rates achieved by the two preparations, and 55 per cent of the cases that had failed to respond to conventional treatment responded to the additional treatment.     

Relationship between penetrability of the papillary duct (teat) and phagocytic capability in lactating dairy cows

To determine whether there is a reciprocal relationship between penetrability of the papillary duct of the teat (streak canal) and phagocytic capability, 3 cows with highly penetrable papillary ducts and 3 with ducts highly resistant against penetration were identified, using a penetrability assay. Leukocytes harvested from milk from these cows were tested for their capability to phagocytose Staphylococcus aureus. Phagocytic capability was found to be independent of the ability of microorganisms to gain access to the interior of the mammary gland.     

Host-response patterns of intramammary infections in dairy cows

Many different bacterial species have the ability to cause an infection of the bovine mammary gland and the host response to these infections is what we recognize as mastitis. In this review we evaluate the pathogen specific response to the three main bacterial species causing bovine mastitis: Escherichia coli, Streptococcus uberis and Staphylococcus aureus. In this paper we will review the bacterial growth patterns, host immune response and clinical response that results from the intramammary infections. Clear differences in bacterial growth pattern are shown between bacterial species. The dominant pattern in E. coli infections is a short duration high bacteria count infection, in S. aureus this is more commonly a persistent infection with relative low bacteria counts and in S. uberis a long duration high bacteria count infection is often observed. The host immune response differs significantly depending on the invading bacterial species. The underlying reasons for the differences and the resulting host response are described. Finally we discuss the clinical response pattern for each of the three bacterial species. The largest contrast is between E. coli and S. aureus where a larger proportion of E. coli infections cause potentially severe clinical symptoms, whereas the majority of S. aureus infections go clinically unnoticed. The relevance of fully understanding the bovine host response to intramammary infection is discussed, some major gaps in our knowledge are highlighted and directions for future research are indicated.     

Clinical features of consecutive intramammary infections with Streptococcus agalactiae in vaccinated and non-vaccinated heifers

The clinical, haematological and functional changes which followed three consecutive intramammary infections of Streptococcus agalactiae in the first lactation of eight heifers, four of which were systemically hyperimmune to the organism, are described. Irrespective of whether it was a vaccinated or non-vaccinated heifer or first, second or third infection the clinical features during the first 24 hours were characterised by elevated temperatures with hard, swollen and painful infected quarters. First infections were almost all of short duration because of self cure, while second or third infections were prolonged, with intermittent excretion of bacteria and low cell counts. Milk yields of infected quarters were depressed, ranging from 8 per cent in short infections to 31 per cent in chronic infections. All blood parameters remained within normal limits with the exception of total and differential white cell counts, which showed a change from a quantitative to a qualitative response by the third infection. The most significant finding was the absence of any real difference between the systemically hyperimmune and the non-vaccinated heifers, suggesting that circulating antibody has little effect against intramammary infection.     

Herd-level risk factors for Staphylococcus aureus and Streptococcus agalactiae intramammary infections

Herd-level risk factors for high herd prevalence of Staphylococcus aureus and Streptococcus agalactiae intramammary infection were studied using data from Holstein herds participating in the New York State Quality Milk Promotion Services Program during the period 1978–1983. Using information from initial surveys and bacteriologic sampling of all herds, a set of possible risk factors for each organism was examined. Comparisons between herds with high and zero prevalence of each infection were made. Failure to teat dip and use of common cloths or sponges for udder preparation increased the odds of high prevalence for both organisms. Selective or no dry cow therapy, having tie stall or stanchion housing and using dry massage or no udder preparation increased the risk for Str. agalactiae, but not for S. aureus infection. Milking machine function played a role in the risk of both infections.     

Annual incidence, prevalence and transmission characteristics of Streptococcus agalactiae in Danish dairy herds

Contagious mastitis pathogens continue to pose an economic threat to the dairy industry. An understanding of their frequency and transmission dynamics is central to evaluating the effectiveness of control programmes. The objectives of this study were twofold: (1) to estimate the annual herd-level incidence rates and apparent prevalences of Streptococcus agalactiae (S. agalactiae) in the population of Danish dairy cattle herds over a 10-year period from 2000 to 2009 inclusive and (2) to estimate the herd-level entry and exit rates (demographic parameters), the transmission parameter, β, and recovery rate for S. agalactiae infection. Data covering the specified period, on bacteriological culture of all bulk tank milk samples collected annually as part of the mandatory Danish S. agalactiae surveillance scheme, were extracted from the Danish Cattle Database and subsequently analysed. There was an increasing trend in both the incidence and prevalence of S. agalactiae over the study period. Per 100 herd-years the value of β was 54.1 (95% confidence interval [CI] 46.0-63.7); entry rate 0.3 (95% CI 0.2-0.4); infection-related exit rate 7.1 (95% CI 5.6-8.9); non-infection related exit rate 9.2 (95% CI 7.4-11.5) and recovery rate 40.0 (95% CI 36.8-43.5). This study demonstrates a need to tighten the current controls against S. agalactiae in order to lower its incidence.     

Prevention of intramammary infections in dairy cows by the use of a premilking teat dip method with a foaming iodophor dip agent

In this study we investigated the efficacy of premilking teat dipping with a foaming iodophor teat dip in a negative controlled field study. Incidence of new intramammary infections (IMI), incidence of clinical mastitis, influence on somatic cell count (SCC) and the characteristics of udder tissue and teats were used as parameters to evaluate clinical efficacy. Predipping was compared with a negative control using a split-udder experimental design. Right teats were predipped with a foaming disinfectant containing 0.27% iodine while left teats served as controls. The latter were conventionally cleaned with damp cloth towels and dried manually with disposable paper towels ("best cleaning practice"). All teats were dipped after milking with the same dip. There were no differences between treated and control quarters with respect to incidence of new IMI during the study period (treated quarters: 6.6% vs. untreated: 6.95%), incidence of clinical mastitis (30 cases in the treatment group vs. 39 cases in the control group) and geometric mean of SCC of quarter milk samples. Spectrum of detected pathogens was also comparable. Condition of udder tissue and teat ducts did not differ between treated and control quarters.     

Relationship between California Mastitis Test score and ultrasonographic teat measurements in dairy cows

Objective The majority of published studies about mastitis are related to the control and prevention of mastitis, with particular emphasis on eliminating predisposition factors. The objective of the current study was to determine the role of teat morphology as an important factor in the aetiology of mastitis. Design Ultrasonographic measurements were taken from 190 teats from 100 dairy cows of different breeds. Procedure Mastitis in cows was diagnosed by the California Mastitis Test (CMT) and microbiological tests. The data were evaluated in the light of the clinical history of the animals. Results Main effects of breed on teat diameter at the position of the Furstenberg rosette (FTD) and teat cistern diameter (CD), that of age on FTD and overall teat diameter (OTD), and that of CMT score on CD and OTD were significant (P < 0.05, P < 0.01). Number of lactations, pregnancy, the lactation period and the udder lobe (rear, front) were not found to have a significant effect on any of the measurements. Results showed that CD was significantly smaller (1.44 ± 0.04 cm) (P < 0.01) in CMT‐positive udder lobes than that in CMT‐negative lobes. No difference was detected in canal length, CD, teat wall thickness, OTD or FTD between the CMT‐positive and ‐negative lobes. Conclusion The occurrence of mastitis could be related to specific ultrasonographic teat measurements (e.g. CD, OTD and FTD) and these may be important in the breeding of cows with a predisposition to mastitis, as well in the evaluation of in‐herd cows in terms of udder/teat deformities.     

Managerial risk factors of intramammary infection with Streptococcus agalactiae in dairy herds in Ohio.

Dairy herds in Ohio were selected by stratified random sampling for participation in a disease-monitoring study to relate Streptococcus agalactiae intramammary prevalence to herd management and environmental conditions. Of 48 herds studied, 27 herds had at least 1 cow infected with this pathogen. Management and environmental conditions were assessed by direct observation as well as by an interview with the dairy producers. One-way ANOVA or chi 2 analysis, with presence or absence of Streptococcus agalactiae as the dependent variable, was used to test each of 70 independent variables. Variables found significant at P less than 0.20 were further evaluated by use of logistic regression. Our sample size permitted only 4 independent variables to be simultaneously evaluated by logistic regression. The most predictive risk factors were identified as poor teat and udder hygiene, poor environmental sanitation, large herd population, and use of a shared washcloth for premilking cleaning of teats and udders.     

Epidemiology of Streptococcus uberis intramammary infections in a dairy herd.

From 1987 to 1991, almost 36,000 quarter samples of mammary secretion representing 1790 lactations of 510 dairy cows from a research herd were collected for bacteriological examination. The percentage of cows infected with Streptococcus uberis ranged from 12 to 16% of cows/year. S. uberis was isolated from 14.2% of lactations over the 5-year period. The prevalence of S. uberis intramammary infection (IMI) was significantly higher in cows with > or = 4 lactations than in cows with 3 or fewer lactations. Regardless of lactation number, the prevalence of S. uberis was highest before parturition, during early lactation and near drying off. The prevalence of S. uberis infected quarters ranged from 1.3 to 2.3% of quarters/year; the prevalence rate for the 5-year period was 2% of quarters. The quarter prevalence of S. uberis was lowest in cows with < or = 3 lactations, increased significantly with lactation number and was highest in cows with > or = 6 lactations. The percentage of quarters infected with S. uberis varied significantly by year. The majority (95%) of S. uberis IMI were subclinical. The ratio of subclinical IMI to clinical IMI was lowest during early lactation, and increased with days in milk, and with lactation age except for cows in their 5th and 6th lactations. Results of this epidemiological investigation suggest that opportunities exist where suitable control measures could be applied to reduce the impact of S. uberis infections in the dairy herd.     

Milk protein profiles in response to Streptococcus agalactiae subclinical mastitis in dairy cows

The objective of this study was to investigate the milk protein profiles of normal milk and those of milk during the course of subclinical mastitis, caused by natural Streptococcus agalactiae infection. Two‐dimensional gel electrophoresis and liquid chromatography mass spectrometry were used to assess protein profiles and to identify the proteins. The results showed that S. agalactiae subclinical mastitis altered the protein profiles of milk. Following Mascot database matching, 11 and 12 protein types were identified in the milk collected from healthy and S. agalactiae subclinical mastitic udders, respectively. The distinct presence of the antibacterial protein cathelicidin‐1 was detected in infected milk samples, which in turn was highly correlated to the severity of subclinical mastitis as represented by the milk somatic cell count (r = 0.616), but not the bacterial count. The protein profile of milk reveals changes in the host response to S. agalactiae intramammary infection; cathelicidin‐1 could therefore serve as a biomarker for the detection of subclinical mastitis in dairy cows.     

Efficacy of using an internal teat sealer to prevent new intramammary infections in nonlactating dairy cattle

OBJECTIVE: To determine whether insertion of an internal teat sealer (ITS) at the end of lactation would prevent development of new intramammary infections (IMIs) during the nonlactating period. DESIGN: Controlled clinical trial. ANIMALS: 939 Holstein-Friesian dairy cows from 16 herds. PROCEDURES: Results of bacteriologic culture of milk samples collected 14 days prior to the end of lactation were used to assign cows to groups (group 1 = negative results for all quarters; group 2 = positive results for > or = 1 quarter). Quarters of cows in group 1 were treated with an ITS or a single intramammary dose of cloxacillin; quarters of cows in group 2 were treated with cloxacillin in conjunction with an ITS or with cloxacillin alone. Milk samples were collected at the end of lactation and within 8 days after calving. RESULTS: Regardless of whether the outcome of interest was new IMIs caused by any pathogens, major pathogens, environmental pathogens, or streptococci other than Streptococcus agalactiae, quarters in group 2 treated with both cloxacillin and an ITS were less likely to develop a new IMI than were quarters treated with cloxacillin alone. For cows in group 1, no significant difference in risk of new IMIs was found between treatments. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that for dairy cattle with an IMI late in the lactation period, intramammary administration of cloxacillin at the end of lactation followed by insertion of an ITS enhanced protection against development of new IMIs, compared with use of cloxacillin alone.     

Efficacy of extended pirlimycin hydrochloride therapy for treatment of environmental Streptococcus spp and Staphylococcus aureus intramammary infections in lactating dairy cows

Fifty-one chronically infected lactating dairy cows were used to evaluate the efficacy of extended pirlimycin therapy regimens for treatment of intramammary infections by environmental Streptococcus spp and Staphylococcus aureus. Cows (n = 47) with one or more infected mammary quarters were blocked by parity and randomly allocated to one of three groups for treatment with pirlimycin (50 mg/mammary quarter) as follows: one treatment per day for 2 days (n = 36 infected mammary quarters); one treatment per day for 5 days (n = 36 infected mammary quarters); and one treatment per day for 8 days (n = 20 infected mammary quarters). Four cows with nine infected mammary quarters were included as untreated controls. Milk samples from each mammary quarter were collected 7 days before treatment, immediately before treatment, and weekly for 4 weeks after the final treatment for microbiological evaluation. A bacteriologic cure was defined as a treated, infected quarter that was bacteriologically negative for the presence of previously identified bacteria at weekly intervals after treatment. Efficacy of pirlimycin therapy against intramammary infections caused by environmental Streptococcus spp and S. aureus was 44.4%, 61.1%, and 95.0% for the 2-, 5-, and 8-day treatment regimens, respectively. None of the infections in the untreated control quarters was cured. Significant differences in efficacy were detected between all pirlimycin groups and the untreated control group, between the 8- and 2-day treatment regimens, and between the 8-day and 5-day treatment regimens (P < or = .05). Results of this study indicate that extended pirlimycin therapy was effective in eliminating intramammary infections caused by environmental streptococci and S. aureus in lactating dairy cows.     

Intramammary infections in a dairy herd with a low incidence of Streptococcus agalactiae and Staphylococcus aureus infections.

In a dairy herd with a low incidence of intrammary infections due to Streptococcus agalactiae and Staphylococcus aureus, clinical mastitis remained a serious problem despite good control of nonclinical mastitis through postmilking teat disinfection and antibiotic therapy of known infected quarters at the end of lactation. During the 2-year study, the incidence of clinical mastitis was 0.88 cases/cow-year; 32.2% were caused by streptococcal species other than Str agalactiae and 33.5% by gram-negative organisms. Among all new infections detected, 54.1% were caused by streptococcal species other than Str agalactiae and 25.7% by gram-negative bacteria. Among new infections, 41.6% occurred during the nonlactating period or within a few days of calving. Incidence of clinical mastitis was highest in the 1st month of lactation. Among 84 gram-negative infections, 42.8% were caused by Klebsiella pneumoniae, 20.2% by Escherichia coli, and 23.8% by Enterobacter spp. Among the many serotypes of K pneumoniae and E coli, none was predominant.     

Associations between teat injuries and fistula formation in lactating dairy cows treated with surgery

OBJECTIVE: To determine associations between rate of fistula formation and parity, lactation period, wound age, wound location, and shape of teat injuries in surgically treated teats in dairy cows. STUDY DESIGN: Prospective clinical study. ANIMALS: 106 lactating dairy cows with teat lacerations. PROCEDURES: Lacerations were classified via shape, location, and age. Associations between potential risk factors and fistula formation were analyzed. Seasonal distribution, type of injured teat, parity, and days in lactation were determined. RESULTS:Cows with teat injury in their first and second parity had 4.1 times the odds of fistula formation, compared with cows with parity >or= 3.Teats sutured within 48 to 72 hours of injury had 8.3 times the odds of fistula formation, compared with teats sutured within the first 24 hours. Cows in early lactation stage (first 60 days of lactation) were more susceptible to teat injuries. Occurrence of teat injury was greater at the third, fourth, and fifth parity. CONCLUSIONS AND CLINICAL RELEVANCE: Season, parity, and lactation period were associated with prevalence of teat injury in lactating dairy cows in a range system. Neither the type of suture material used nor the suturing technique was associated with effects on healing of the operated full-thickness teat wounds. Factors such as parity and age of the wound can be associated with delay in the healing process, which may result in fistula formation.     

Nisin抗菌肽治疗奶牛无乳链球菌性隐性乳房炎后主要乳成份的变化

将36头无乳链球菌引起的隐性乳房炎奶牛分成试验组和对照组,每组18个病例.试验组奶牛用Nisin抗菌肽经患病乳房内灌注,每天1次,连续治疗3 d,对照组奶牛不治疗.分别采集治疗前和治疗后1、3、5周的奶样进行细菌学检查,体细胞含量测定和乳成份分析.结果表明,经Nisin治疗后,细菌阳性乳区数和体细胞教(SCC)大于500 000/mL乳区数量均显著降低,牛奶中脂肪、蛋白质、乳糖和总固体含量有升高趋势,尤其是蛋白质和乳糖的含量显著高于治疗前.由此可见,Nisin乳房内注入对于奶牛无乳链球菌性隐性乳房炎具有良好的治疗作用.     

Determination of antibodies to Streptococcus agalactiae in the milk of dairy cows using the ELISA test

A sensitive 4-layers ELISA test for determination of antibodies against the pathogens of Streptococcus agalactiae in cows' milk was used for diagnosis of mastitis, with the aim to broaden these methods. Antigen was linked on the solid phase in the form of the whole bacteria, and milk was tested, diluted in the ratio of 1:10. Antigen bound-specific antibodies were labelled with pig antibodies against bovine immunoglobulins and in the next layer with rabbit antibody conjugated with peroxidases against pig immunoglobulins. After test visualisation and reading on the photometre, the results were given in the positivity per cent as a 100-multiple of the proportion of absorbance of the unknown sample and the positive control after subtraction of the negative control. Milk was examined in 36 dairy cows from three various breeding herds by that method. The samples were parallelly examined bacteriologically and cytologically. In the milk of dairy cows with positive S. agalactiae finding, the main level of antibodies expressed a positivity per cent, was 15.0%, while in bacteriologically negative animals it was only 6.2%. The dairy cows were divided into 8 groups, characterizing various stages of mastitis, according to the results of the individual treatments.