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1.
Eighteen dairy herds were studied, 12 with a 12-month Dairy Herd Improvement Association herd mean somatic cell count (SCC) less than or equal to 150,000 cells/ml (low SCC) and 6 with a 12-month mean SCC greater than 700,000 cells/ml (high SCC). At the outset of the study, quarter samples for bacteriologic culture were collected (in duplicate) from all quarters of all lactating cows (whole herd culture). Subsequently, quarter milk samples for culture from all cows with clinical mastitis were collected for a period of 6 months. In the herds with low SCC, results of whole herd culture revealed low prevalence of intramammary infection attributable to all major pathogens (less than 4% of all quarters). Prevalence of infection with Streptococcus agalactiae (22.2% of all quarters) and Staphylococcus aureus (6.6% of all quarters) was significantly (P less than 0.05) higher in the herds with high SCC. Mean incidence of clinical mastitis in the herds with low SCC was 4.23 infections/100 cows/month (range, 0.42 to 10.25 infections). In the herds with high SCC, mean incidence was 2.91 infections/100 cows/month (range, 1.33 to 3.92 infections). In the herds with low SCC, infection type, as mean percentage of total clinically infected quarters sampled for culture/herd, was 0.0%, 2.2%, 12.3%, 43.5%, and 28.6% for Str agalactiae, S aureus, streptococci other than Str agalactiae, coliforms, and organisms not isolated, respectively. Respective percentages for the herds with high SCC were 41.5%, 18.3%, 12.6%, 8.0%, and 8.8%. During the study period (from April through January), incidence of clinical mastitis and clinical mastitis caused by coliform bacteria were highest in July and August for herds with low SCC.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

2.
Twelve dairy herds that had participated in the Pennsylvania Dairy Herd Improvement Association (DHIA) program for at least 12 months, that had a 12-month mean DHIA somatic cell count greater than 700,000 cells/ml, and that had greater than 25% of lactating cows infected with Streptococcus agalactiae participated in a herd blitz treatment program. Initially, quarter milk samples for bacteriologic culturing were collected from all lactating cows. Subsequently, all cows identified as infected with Str agalactiae were treated, using a commercial penicillin-novobiocin intramammary infusion product. In addition, a herd mastitis management program of postmilking teat dipping and treatment of all cows at the start of the nonlactating period was instituted. Thirty days after the initial herd visit, samples from all lactating cows were again cultured, and cows infected at that time were treated. Twelve months after the initial herd visit, samples from all lactating cows were again cultured. Mean prevalence of infection with Str agalactiae decreased (P less than 0.05) from 23.0% of quarters and 41.6% of cows initially to 3.4% of quarters and 9.3% of cows at 30 days and 1.6% of quarters and 4.2% of cows at 1 year. Mean herd DHIA somatic cell count decreased (P less than 0.05) from 918,000 cells/ml initially to 439,000 cells/ml at 30 days and 268,000 cells/ml at 1 year.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

4.
Quarter samples from twenty-five dairy herds, representing 223 herds supplying direct to Brisbane, were cultured and submitted to the Wisconsin Mastitis Test (WMT). Thirteen herds had a history of producing bulk milk with a consistently high WMT score (greater than 15 mm) and in twelve herds the WMT score was consistently low. Prevalence of infection was higher in group A herds (22.2% quarters were infected with Staphylococcus aureus or streptococci) than in group B herds (9.8% of quarters were infected). There was considerable scatter of prevalence among both groups of herds. Overall, S. aureus was found in 19% of cows and 7% of quarters, and Streptococcus agalactiae in 15% of cows and 7% of quarters. Quarters from group A herds showed a higher WMT score than those in group B herds whether infected with S. aureus, Str. agalactiae, micrococci or yielded no detectable organisms. It was concluded that regular surveys are required of the high cell count herds to monitor mastitis status in the industry.  相似文献   

5.
Mannitol agar for microbiologic diagnosis of bovine mastitis   总被引：1，自引：0，他引：1  
A medium containing mannitol (mannitol agar) was developed and evaluated as a tool for the microbiologic diagnosis of bovine mastitis. Mannitol agar supported growth of all important bacterial mastitis pathogens (staphylococci, streptococci, coliforms, and pseudomonads) except Corynebacterium pyogenes. Color change around colonies in the agar permitted the differentiation of pathogenic from nonpathogenic staphylococci. Most Staphylococcus aureus strains and some Staphylococcus epidermidis strains produced yellow zones. These yellow zone-producing strains (mannitol fermenters) of staphylococci were obtained from quarters with significantly elevated (P less than 0.05) somatic cell counts (SCC) in the milk, as compared with uninfected quarters and, therefore, would be considered pathogens. Mannitol-negative strains of S epidermidis (those with red zones) were obtained from quarters with SCC similar to those of uninfected quarters. The streptococci could be divided into 2 groups on the basis of color change around the colonies: Streptococcus agalactiae, Str dysgalactiae, and group G streptococci produced red zones; Str uberis, Str bovis, and enterococci produced yellow zones. Pathogenic streptococci (Str agalactiae, Str dysgalactiae, Str uberis, and group G streptococci) were obtained from quarters with SCC significantly higher (P less than 0.01) than those of uninfected quarters. Streptococcus bovis and enterococci were obtained from quarters with SCC similar to those of uninfected quarters and were considered nonpathogenic. Pathogenic streptococci were found in much higher concentration than nonpathogenic streptococci and could be differentiated on that basis.  相似文献   

6.
Quarter samples (n = 6,328) of mammary secretions were collected from 160 cows during physiologic transitions of the udder to determine the frequency of isolation of mastitis-causing pathogens and the incidence of new intramammary infections (IMI) during the nonlactating period. None of the cows in the herd was infected with Streptococcus agalactiae, and the prevalence of Staphylococcus aureus was low. Cows were not treated with antibiotics at cessation of milking. A threefold increase in the percentage of quarters infected with major mastitis-causing pathogens developed from late lactation to early involution. Coliforms and streptococci other than Str agalactiae accounted for 94% of major pathogen infections. The number of quarters infected with coagulase-negative staphylococci increased slightly from late lactation to early involution, whereas the number of quarters infected with Corynebacterium bovis decreased markedly. Major pathogens caused 101 of 153 IMI at parturition and greater than 90% were caused by streptococci and coliforms. At parturition, 51 of 52 minor pathogen IMI were caused by coagulase-negative staphylococci. During early lactation, there was a marked decrease in quarters infected with major pathogens; however, the number of quarters with major pathogen IMI during early lactation was 2.3 times higher than the number of quarters infected before cessation of milking. The number of quarters with minor pathogen IMI during early lactation was the same as at parturition, but a marked decrease in quarters infected with coagulase-negative staphylococci and a marked increase in C bovis IMI developed from parturition to early lactation.  相似文献   

7.
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.  相似文献   

8.
In 57 Holstein cows where the dairy farm uses a milking parlor system, the somatic cell count (SCC) increased persistently in the bulk milk (monthly mean 52.3 x 10(4) cells/ml; range 21 to 94 x 10(4) cells/ml). We detected S. aureus in 24 (41.2%) of the 54 lactating cows and in 29 (12.8%) of 227 quarters of the 57 milking cows in the herd. A control program was implemented in an effort to eradicate S. aureus mastitis from this dairy farm. The control plan established improved handling of the lactating cows, improved milking procedures, dry-cow therapy, and culling of infected cows. The program was monitored for 3.5 years by frequent checkups on the rate of S. aureus infection, the SCC, and the changes in milk composition. Eighteen months after the control program was started, the rate of S. aureus infection in the quarter milk decreased dramatically, and no S. aureus isolates were found in the milk of the remaining cows. The SCC in the bulk milk of the herd dropped to a monthly mean of <20 x 10(4) cells/ml. In conclusion, the control program was effective for controlling persistent S. aureus mastitis in this dairy herd.  相似文献   

9.
Two beef cow herds were investigated to determine the prevalence of subclinical mastitis and to determine whether it contributed to decreased weaning weight of calves nursed by affected cows. Quarter samples obtained about 30 days after calving were evaluated by the California mastitis test and by direct microscopic cell count. In 1 herd, a 92-cow confinement operation, 17 quarters of 12 cows were infected with Staphylococcus aureus, Streptococcus sp other than agalactiae, or Klebsiella sp. Mean 205-day adjusted weights were 203.9 kg and 218.2 kg for calves nursed by infected vs noninfected cows. In the other herd, a 75-cow range-pasture operation, 8 quarters of 8 cows were infected, all with S aureus. Mean 205-day adjusted weights were 162.5 kg and 174.6 kg for calves nursed by infected vs noninfected cows.  相似文献   

10.
Two dry-cow therapy products were evaluated in seven factory-supply dairy herds in the Waikato area. A product containing neomycin sulphate and the benzathine salt of penicillin (Neopen D.C. White; Smith-Biolab) was used in five herds, and one containing benzathine cloxacillin (Orbenin, Beecham) was used in two herds. Non-treated control cows were included in each herd. Both products were effective in eliminating intramammary infections with Staphylococcus aureus, Streptococcus uberis, and Streptococcus agalactiae. Efficacy of dry-cow therapy against S. aureus was 83.8% and 85.2% respectively. Spontaneous cure rate among controls was 30.8% for S. aureus during the dry period. Spontaneous cure rate for Str. uberis was 50%, while dry-cow therapy eliminated 100% and 77.8%, respectively, for the two products. Dry-cow therapy with either product eliminated more than 90% of Str. agalactiae infections while spontaneous cure rate was only 28.6%. These results further support the effectiveness of dry-cow therapy in reducing the level of subclinical mastitis in dairy herds by shortening the duration of intramammary infections.  相似文献   

11.
Dairy production is not traditional in Vietnam. The farmers have little practical knowledge and udder health control is generally lacking. In order to give the farmers appropriate advice, knowledge about the distribution of udder pathogens is crucial. The aim of the study was to investigate the prevalence of sub-clinical mastitis and to identify udder pathogens isolated from smallholder dairy herds in Southern Vietnam. Twenty farms with a herd somatic cell count (SCC) ranging from low (≤400?×?103?cells/mL) to high (>400?×?103?cells/mL) were randomly selected. Milk samples were collected from 458 quarters of 115 clinically healthy cows. SCC was analyzed on farm by a portable cell counter. Bacteriological samples were taken using Mastistrip© cassettes and sent to Sweden for examination. For all herds the mean herd SCC was 632?×?103/mL milk. The prevalence of subclinical mastitis at quarter SCC basis was 63.2 % and at cow basis 88.6 %. Only 40 % of all cows were bacteriologically negative in all quarters. Streptococcus agalactiae was the most commonly found bacteria species, isolated from 96 of the 458 quarter samples, in 13 of the 20 farms. The results indicate pronounced subclinical mastitis problems among the dairy cows in this region mainly due to infections with S. agalactiae. The high prevalence of this highly contagious pathogen is probably attributable to the generally poor milking hygiene and low awareness of proper measures to prevent occurrence and spread of udder infections. A strict, targeted action program for the herds in this area is required in order to lower the prevalence of subclinical mastitis.  相似文献   

12.
Bacteriological examinations were made on quarter samples from cows in 35 herds over a 3 year period to monitor the response in a mastitis control program. Initially, Staphylococcus aureus predominated in 32 of the herds and the mean herd prevalence was 26%. The control measures halved this rate but there was considerable variation in response between herds. The decline occurred rapidly and there was a significant reduction (P less than 0.01) by 3 months. Streptococcus agalactiae predominated in 3 herds and the overall infection rate was 4.9%. Control measures eliminated the infection completely from most herds but reinfection occurred in 2 herds. The greatest decline occurred in the first 6 months and was significant (P less than 0.05). The measures had little effect upon Str. uberis and Str. dysgalactiae which remained fairly consistently at low levels. Initially, strains of Staph. aureus resistant to penicillin were dominant in most herds. In a minority of herds strains resistant to streptomycin predominated and in these herds there was a concurrent resistance to penicillin. These patterns did not change greatly over the control period. Resistance by Str. agalactiae to streptomycin occurred in most herds at the start of the program.  相似文献   

13.
Prevalence of udder infections and mastitis in 50 California dairy herds   总被引：2，自引：0，他引：2  
The California mastitis test (CMT) and bacteriologic culture were performed on samples of bulk-tank milk and cow-composite milk (n = 23,138 cows) from 50 California dairies, 19 of the 50 with known mastitis problems. Thirty-eight (76.0%) bulk-tank milk samples and 12,334 (53.3%) cows were positive by results of the CMT. Potential mastitis agents were isolated from 5,085 (22%) cows. Staphylococcus aureus was isolated from all 50 herds, Streptococcus agalactiae was isolated from 47 herds, and Mycoplasma sp was isolated from 24 herds. For cow-composite milk samples, the prevalences were 9.3% for Str agalactiae, 9.1% for S aureus, 0.9% for Mycoplasma sp, 1.2% for coliform bacteria, 0.9% for other streptococci, 0.8% for coagulase-negative staphylococci, and 1.3% for other organisms. The relative sensitivity and the relative specificity of the CMT performed on cow-composite milk samples were 83.4% and 55.2%, respectively, and the predictive value of positive CMT results was 34.2%.  相似文献   

14.
A case-control study was undertaken during the summer of 1989 in central Alberta dairy herds to identify independent predictors of nocardial mastitis. Thirty-seven herds with nocardial mastitis were matched with control herds based on herd size, milk production, and enrolment in Alberta Dairy Herd Improvement Services. Control herds were considered free of nocardial mastitis based on negative cultures of four weekly bulk tank milk samples and one composite milk sample collected during the same period from each lactating cow in the herd. A detailed questionnaire on herd management was completed during farm visits. The use of blanket dry cow therapy was not found to be a risk factor for nocardial mastitis. Dry cow therapy with intramammary products containing neomycin and the use of multidose vials of dry cow medications were the only predisposing factors identified as being significantly associated with nocardial mastitis in central Alberta dairy herds. Use of neomycin as a dry cow therapy increased the odds of nocardial mastitis occurring in these dairy herds by 169 times.  相似文献   

15.
In this investigation electrical conductivity (EC) and somatic cell concentration (SCC) were compared in 3 herds for their ability to correctly identify the infection status of quarters. For EC, thresholds of 6.0 and 6.8 mS/cm were used and comparisons were made between quarters within each cow. The method of comparison between quarters was the same as that described by the manufacturers of the AHI Mastitis Detector. For SCC a threshold of 500 x 10(3) cells/ml was used. For both EC and SCC considerable variation was found between herds for sensitivity (the proportion of quarters infected with a major pathogen and detected as abnormal), and specificity (the proportion of quarters free from infection and detected as normal). The mean sensitivity and specificity of EC for the three herds was 49% and 79% respectively, whereas for SCC the means were 71% and 81% respectively. The variation in sensitivity and specificity of EC between herds was attributed to differences in the distribution of EC for quarters of similar infection status. It was concluded that these differences in herd EC precluded the use of pre-determined EC thresholds which were applicable for detecting mastitis in all herds.  相似文献   

16.
OBJECTIVE: To identify herd characteristics and management practices associated with bulk-tank somatic cell counts (BTSCC) in dairy herds in Ohio enrolled in official Dairy Herd Improvement Association (DHIA) programs. SAMPLE POPULATION: 186 dairies in Ohio. PROCEDURE: All herds in official DHIA programs in 9 counties were asked to participate. Extensive information regarding herd characteristics and management practices was obtained, using a standardized questionnaire. Bulk-tank milk samples were requested from all participating herds for bacterial culture. Official DHIA test-day records for January 1997 were obtained from all herds enrolled in official DHIA programs in the 9 counties. Potential associations were identified, using multivariable ANOVA. RESULTS: Participation was 186 of 479 (39%) herds. Streptococcus agalactiae and Mycoplasma spp were not isolated from bulk-tank milk samples. Staphylococcus aureus was isolated from 64 of 172 (37%) of the herds. The BTSCC were inversely associated with peak daily milk production, postmilking teat disinfection, percentage of eligible cows in the herd detected in estrus, and directly related to the extent to which BTSCC was perceived as a herd problem during the preceding 2 years. Type of housing for nonlactating cows and product used for treatment of nonlactating cows also were significantly associated with BTSCC. CONCLUSIONS AND CLINICAL RELEVANCE: Consideration of herd characteristics and implementation of management practices associated with BTSCC could result in increased milk yield and production of milk with lower BTSCC.  相似文献   

17.
In this investigation electrical conductivity (EC) and somatic cell concentration (SCC) were compared in 3 herds for their ability to correctly identify the infection status of quarters. For EC, thresholds of 6.0 and 6.8 mS/cm were used and comparisons were made between quarters within each cow. The method of comparison between quarters was the same as that described by the manufacturers of the AHI Mastitis Detector. For SCC a threshold of 500 × 103 cells/ml was used.

For both EC and SCC considerable variation was found between herds for sensitivity (the proportion of quarters infected with a major pathogen and detected as abnormal), and specificity (the proportion of quarters free from infection and detected as normal). The mean sensitivity and specificity of EC for the three herds was 49% and 79% respectively, whereas for SCC the means were 71% and 81% respectively.

The variation in sensitivity and specificity of EC between herds was attributed to differences in the distribution of EC for quarters of similar infection status. It was concluded that these differences in herd EC precluded the use of pre-determined EC thresholds which were applicable for detecting mastitis in all herds.  相似文献   

18.

Background

The objectives of this study were to investigate whether there were differences between Norwegian Red cows in conventional and organic farming with respect to reproductive performance, udder health, and antibiotic resistance in udder pathogens.

Methods

Twenty-five conventional and 24 organic herds from south-east and middle Norway participated in the study. Herds were matched such that geographical location, herd size, and barn types were similar across the cohorts. All organic herds were certified as organic between 1997 and 2003. All herds were members of the Norwegian Dairy Herd Recording System. The herds were visited once during the study. The relationship between the outcomes and explanatory variables were assessed using mixed linear models.

Results

There were less > 2nd parity cows in conventional farming. The conventional cows had higher milk yields and received more concentrates than organic cows. Although after adjustment for milk yield and parity, somatic cell count was lower in organic cows than conventional cows. There was a higher proportion of quarters that were dried off at the herd visit in organic herds. No differences in the interval to first AI, interval to last AI or calving interval was revealed between organic and conventional cows. There was no difference between conventional and organic cows in quarter samples positive for mastitis bacteria from the herd visit. Milk yield and parity were associated with the likelihood of at least one quarter positive for mastitis bacteria. There was few S. aureus isolates resistance to penicillin in both management systems. Penicillin resistance against Coagulase negative staphylococci isolated from subclinically infected quarters was 48.5% in conventional herds and 46.5% in organic herds.

Conclusion

There were no large differences between reproductive performance and udder health between conventional and organic farming for Norwegian Red cows.  相似文献   

19.
The culture of a sample of bulk tank milk may be a useful technique by which to screen herds for major mastitis pathogens. Staphylococcus aureus and Streptococcus agalactiae, if identified on a culture of a sample of bulk milk, reliably indicate infection of the udder. Environmental bacteria, such as the other streptococci and coliforms, are unlikely to be indicative of the proportion of cows infected with these organisms.Samples of bulk milk are readily obtainable and can be rapidly and inexpensively cultured to screen large numbers of herds for mastitis-causing bacteria, yet the performance of the test has only recently been formally assessed for its ability to correctly classify herds according to infection status.A single culture of bulk tank milk has been found to be a test with low sensitivity and high specificity for determining the presence of S. agalactiae or S. aureus in the herd. This means that many infected herds will be called negative, but few uninfected herds will be classified as positive.The literature assessing the performance of bulk tank milk culture in comparison with other mastitis screening tests, the use of bulk milk culture for prevalence surveys, and factors affecting these results is discussed.  相似文献   

20.
For efficient disease management in dairy production, the influence of disease prevention strategies on farm profitability must be known. A survey of mastitis control practices, milking machine function and maintenance, and cow environmental conditions was conducted with 406 dairy producers on the Michigan Dairy Herd Improvement-somatic cell counting program responding. These survey data, in conjunction with Dairy Herd Improvement production data, were used to develop a model estimating the marginal value products of mastitis control practices. Lost milk production associated with increased somatic cell count was calculated for each herd. Mastitis control practices, milking machine function and maintenance, and cow environmental conditions were used as independent variables in an analysis of covariance model with lost milk production as the dependent variable. Variables significant in explaining changes in production from increased somatic cell count were the use of teat dip, use of sanitizer in the wash water, milking cow bedding, summer nonlactating cow housing, summer calving locations, type of regulator, alternating pulsation, and rolling herd average milk production. The marginal value product (change in revenues received) from the use of iodine, chlorhexidine, and quaternary ammonium-type teat dips were $13.79, $16.09, and $22.17/cow/year, respectively, and these changes were statistically significant. However, sanitizer in the wash water was associated with a decrease in production. Management practices that have previously been shown to be economical and did not appear in the final model included nonlactating cow therapy and single-use paper towels.  相似文献   

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