首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Milk samples of 201 ewes were examined in 6 week intervals during a complete lactation period. Those samples were analyzed for the presence of pathogenic bacteria and the somatic cell count was determined. Besides, the California Mastitis Test (CMT) was performed and the udder was clinically examined. The cell counts were found to depend on the lactation period. During 6 weeks following parturition the cell count was 63,000 cells/ml. This number decreased towards the 24th week of lactation to 32,000 cells/ml. At the end of lactation this value increased again to 425,000 cells/ml. The median value of ewes with normal udder health was 56,000 cells/ml milk. For samples from which pathogenic bacteria were isolated this value was 159,000 cells/ml. The most frequent pathogens isolated from the milk samples were coagulase-negative cocci (59.6% of bacteriologically positive samples), the median number being 88,000 somatic cells/ml in these sheep. Coagulase-positive cocci were isolated in 25.3% of the samples, the median value of the cell count was 295,000 cells/ml. In 12.1% of the samples streptococci were found. The median value was 167,000 cells/ml. From the remaining 3.0% of bacteriologically positive samples Pasteurellae, E. coli and Actinomycetae were isolated. The median value of the somatic cell count was 184,000 cells/ml. We consider coagulase-positive cocci therefore as the most pathogenic bacteria for the ovine udder.  相似文献   

2.
The bacterial causes of subclinical mastitis were determined in samples of milk taken from one half of the udders of 159 goats in three different herds. The mean prevalence of subclinical infection was 33 percent, with prevalences of 26 percent, 39 percent and 42 percent in the three herds. Staphylococcus aureus was isolated from seven (13 percent) of the 53 infected halves, coagulase-negative staphylococci accounted for 47 percent, Corynebacterium species for 31 percent and alpha-haemolytic streptococci for 6 percent of the infected samples. The mean somatic cell count of the uninfected milk samples was 428,000 cells/ml, and 93 percent of uninfected samples had counts less than 1,000,000 cells/ml; the mean cell count of the infected samples was 2,785,000 cells/ml.  相似文献   

3.
The association between quarter somatic-cell counts (QSCCs) of milk and the risk of clinical mastitis (CM) was investigated in a 1-year study on three dairy herds in Somerset, UK. The three herds had 95-130 milking cows and an annual mean bulk milk somatic-cell count (BMSCC) of <150 x 10(3)cells/ml. The farms were visited every 4-6 weeks at morning milking when quarter-milk samples were collected. The farmers recorded all cases of CM and were trained to collect sterile milk samples from affected quarters, before treatment for bacteriology.The three herds had CM incidence rates of 25.4, 55.2, and 67.6 quarter-cases per 100 cow-years. Escherichia coli and Streptococcus uberis were cultured from approximately 50% of cases. QSCC was categorised and the risk of CM occurring in the month after the QSCC was examined using multilevel models to account for the correlated nature of the dependent data. Three models were developed: one for all cases of CM, one for those caused by coliforms and one for those caused by S. uberis. When all cases of CM were considered, quarters with somatic-cell count (SCC) 21-100 x 10(3)cells/ml had reduced odds (OR=0.60, P=0.06) and quarters with SCC >200 x 10(3)cells/ml has over three time the odds (OR=3.7, P<0.01) of CM compared with QSCC 1-20 x 10(3)cells/ml. When only coliform CM were investigated, quarters with SCC 6-200 x 10(3)cells/ml had reduced odds of coliform CM (OR=0.47, P=0.04) compared with QSCC 1-5 x 10(3)cells/ml, and SCC >200 x 10(3)cells/ml were not significantly different from the baseline. Finally, when S. uberis CM were investigated, quarters with SCC >200 x 10(3)cells/ml had more than three times the odds of S. uberis CM compared with QSCC 1-20 x 10(3)cells/ml (OR=3.73, P<0.01). QSCC <21 x 10(3) and >200 x 10(3)cells/ml are associated with increased odds of CM in the following 4-6 weeks; this association may be pathogen specific.  相似文献   

4.
Intramammary infections and mastitis were monitored on four occasions at three-week intervals in 61 first calf heifers in five dairy herds during the first ten weeks of lactation. Of 940 quarter milk samples examined 65% were classed as negative, 10.4% as positive for mastitis (mainly subclinical), 1.8% as group 3 (infection present but no elevation in somatic cell count) and 22.8% as group 4 (elevated somatic cell count). Seventy-seven percent of the infections detected and identified were those due to coagulase-negative staphylococci, the main species being S. hyicus, S. epidermidis, S. simulans and S. hominis. Other infections detected with Corynebacterium pyogenes (three samples), Escherichia coli (one sample), Micrococcus spp. (one sample), S. aureus (two samples) and Streptococci (non-agalactiae) (seven samples).The geometric mean somatic cell count for 23 quarters infected with coagulase-negative staphylococci was 311 x 10(3) cells / mL compared to 134 x 10(3) cells / mL in noninfected adjacent contralateral quarters. The respective figures for% cell volume in Channel 8 (mainly neutrophils) were 10.6% and 3.5%. There was a highly significant association between herd and the proportion of quarter milk samples in the four mastitis categories.  相似文献   

5.
Somatic cell counts were performed monthly on bulk tank milk samples for all producers in the Ontario counties of Hastings, Lennox/Addington and Prince Edward throughout 1978 and 1979. Other data were obtained via a structured questionnaire and from the records of the Ontario Milk Marketing Board. Many producers have not adopted practices that have been advocated for the integrated control of mastitis. For example, 43.3% of producers surveyed used single service paper towels, 63.3% regularly used teat dip and 56.5% dry cow therapy. The mean of the average monthly somatic cell count for all producers for 1978 was 621.1 x 10(3) cells/mL. This latter value was used to divide the producers into case (higher than average) and control (lower than average) groups. Control herds averaged 95.9 liters more shipped milk per cow per month than case herds. Milk from control herds averaged 0.22 percentage points higher than case herds for each of average fat and lactose, and 0.16 percentage points higher for protein. The linear regression of monthly shipped milk on the respective monthly bulk tank somatic cell count indicated a loss of 13.26 L/cow/month for each 100,000 increase in somatic cell count.  相似文献   

6.
Researchers have reported that as milk yield increases composite milk somatic cell count (SCC) is diluted in cattle with no intramammary infection (IMI) and as a consequence, estimates of SCC from high yields are lower than estimates of SCC from low yields in dairy cows without an IMI. To date, estimates of reduced milk yield associated with high SCC because of intramammary infection have not been adjusted for any dilution of SCC. Ignoring dilution is therefore likely to lead to an overestimate of reduction in yield with increasing SCC. This paper investigates scenarios of the possible impact of dilution and inflammation on the association between somatic cell count and yield. The data used to investigate this relationship come from 8373 monthly records of milk yield and composite somatic cell count, together with incidence of clinical mastitis, which were recorded on 850 cows from five dairy cattle farms in Gloucestershire, UK. Two sets of models were used to investigate dilution and inflammation using two-level hierarchical models. The first set of models was used to estimate the linear (dilution) and log10-linear (inflammation) impact of SCC on the outcome variable milk yield. Five general linear models with increasing inclusion of higher test day SCC values were run. The cumulative categories were test day SCC values of up to and inclusive of 30, 50, 100, 200 and 400x10(3)cells/ml. Linear and log linear SCC influences on milk yield were estimated. At low SCC values the linear SCC predictor was dominant, while at higher values the log linear predictor was dominant. Up to 100x10(3)cells/ml there was mostly a slightly negative linear relationship between SCC and yield, potentially indicating a dilution effect. In the second set of models, three approaches to adjust milk loss for dilution were compared with an unadjusted model. In general, dilution-adjusted SCC values fitted the data better and resulted in a slightly lower milk loss per SCC category compared with unadjusted SCC. In all models with a dilution term there was a significant reduction in yield with SCC>200x10(3)cells/ml.  相似文献   

7.
The somatic cell count (SCC) was determined in 28 milk sheep with normal udder health using the California Mastitis Test (CMT) and a fluoro-opto-electronic cell counter (Partec Counter). The examinations were made at two week intervals throughout the lactation period. 92% of the premilking samples had a negative CMT reaction and in 0.5% of the samples the reaction was distinctly positive. In 95% of the premilking samples the SCC showed less than 200,000/ml and in 95% of the individual total milkings it was less than 350,000/ml. Elevated SCC were common towards the end of lactation when milk yield was low.  相似文献   

8.
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   

9.
The relationship between test-day measures of milk somatic cell count and milk yield was evaluated using the November 1985 test data from 8352 Holstein cattle (2923 primiparous and 5429 multiparous cows) located in ten Tulare County, California dairies. Following correction for herd and stage of lactation effects, design variable regression was used to create separate models for primiparous and multiparous cows predicting the changes in milk production associated with milk somatic cell count class. Cell counts were stratified by 1/2 loge cell count (x1000 cells/mL) units, permitting comparisons with previous studies. Cell counts less than 148,000/mL were not found to be associated with significant reductions in milk yield when compared to the reference class (cell counts less than 20,000/mL). Consistent incremental decreases in milk production were not noted with increasing cell count strata, even following the natural log transformation. The most dramatic production losses were noted in the range of 148,000 to 665,000 cells/mL. Primiparous cattle in the 403,000 to 665,000 cell count strata experienced a 5.22 kg (19.72%) decrease in test-day milk yield. Multiparous cattle in the same class experienced 3.01 kg (7.82%) reductions in milk production. Primiparous and multiparous cows had similar production losses. The study population differed from previous studies on the basis of herd size, milk production and the level of udder health, measured by milk somatic cell count. These differences and the choice of experimental design may in part explain differences in study results and conclusions.  相似文献   

10.
Quarter foremilk samples were taken at 2–3 weekly intervals for several years in a experimental herd comprising about 45 cows. The samples were submitted to bacteriological analysis and somatic cell counting. The most prevalent quarter infections from 1982 to 1988 were by coagulase-negative staphylococci (15–20% of all the quarters sampled). Most of these (75.6%) persisted until drying-off Dry cow therapy eliminated 86.5% of these infections. Comparison of udder quarters within cows, involving 775 samples from pairs of non-infected quarters and quarters infected by coagulase-negative staphylococci, yielded geometric means of somatic cell counts of 210 000 and 420 000 cells/ml, respectively. The correlation (r=0.87) between the herd bulk milk somatic cell count (SCC) and its estimation from the quarter milk somatic cell count performed on the same day allowed us to evaluate the contribution of the different categories of quarters, according to their infection status, to the herd bulk milk SCC. Quarters infected by a major pathogen (8.5% of samples) gave rise to 46.6% of the total number of cells, while quarters infected by coagulase-negative staphylococci (17.8% of samples) gave rise to 18.1%. Although coagulase-negative staphylococci represented only a secondary source of somatic cells as compared to major pathogens, they were not a negligible source considering the threshold of 300 000 somatic cells advocated for herd milk of good quality.  相似文献   

11.
Milk yield and quality were observed on 93 Angus, Brahman, and reciprocal-cross cows over 3 yr to evaluate the interactions of direct and maternal breed effects and heterosis with forage environment. Forage environments were common bermudagrass (BG), endophyte-infected tall fescue (E+), and a rotational system (ROT) of both forages, in which each forage (BG or E+) was grazed during its appropriate season, usually June through October for BG and November through May for E+. Milk yield was estimated each of 6 mo (April through September) via milking machine and converted to a 24-h basis. Milk fat, milk protein, and somatic cell count were analyzed by a commercial laboratory. Heterosis for milk yield was similar among forages, averaging 2.4 kg (P < 0.01). Expressed as percentages of purebred means, heterosis for milk yield was largest on E+ (52.8%), intermediate on ROT (39.3%), and smallest on BG (23.7%). Direct breed effects for milk yield favored Brahman, and they were similar among forages but tended to be larger for E+ (2.5 kg) and ROT (2.8 kg) than for BG (1.3 kg). Direct breed effects for milk fat favored Brahman and were similar among forages but tended to be larger for E+ (1.0%) and ROT (1.0%) than for BG (0.6%). Purebred cows exceeded crossbreds in milk protein by 0.1% on ROT (P < 0.10). Crossbred cows had lower somatic cell counts than purebreds on BG (P < 0.05), E+ (P < 0.01), or ROT (P > 0.30). Heterosis for somatic cell counts as percentages of purebred means was similar for BG (-68.3%) and E+ (-68.9%) and less favorable for ROT (-31.6%). Maternal breed effects for somatic cell count favored Angus on ROT (P < 0.10) with a similar nonsignificant trend on BG and E+. Direct breed effects for somatic cell count favored Brahman on ROT (P < 0.10) with similar nonsignificant trends on BG and E+. These results suggested that a rotation of cows from E+ to BG in the summer can partially alleviate negative effects of E+ on milk yield. Conclusions also indicated an advantage to crossbred cows in somatic cell count and provided evidence of both direct and maternal breed effects for this trait. The results also suggested that direct breed effects for milk yield, milk fat, and somatic cell count and heterosis for milk yield and somatic cell count (as percentages of purebred means) tended to vary with forage environment, indicating a potential for genotype x environment interaction for these traits.  相似文献   

12.
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   

13.
The objective of this study was therefore to present factors affecting somatic cell counts in bovine bulk milk as a result of intramammary infections as well as non-infectious factors. The paper presents also the impact of on-farm management practices on the level of bulk milk somatic cell counts and presents quality indicators in bulk tank milk. At the farm level bulk milk bacterial infection takes place through three main sources: bacterial contamination from the external surface of the udder and teats, from the surface of the milking equipment, and from mastitis microorganisms within the udder. The threshold of 200,000 cells/ml identifies bacteriological negative quarters of the udder. The counts of mammary pathogens in bulk tank milk are relatively low, on average not exceeding 1,000 cfu/ml. Environmental pathogens predominate in bulk tank milk samples with somatic cells count <300 × 10(3) ml.  相似文献   

14.
The aim of this study was to investigate the importance of bacterial growth for the severity of experimental Escherichia coli mastitis, indirectly expressed as the area under the curve of bacterial counts in milk over time. The association of pre-infusion somatic cell count and post-infusion influx of inflammatory cells in milk with severity of infection was also examined. Bacterial growth was studied through culture in milk samples (in vitro) and through monitoring of bacterial counts in milk during the early phase of infection (in vivo) in 36 cows. Individual variation in bacterial counts was more than 2 x 10(2)-fold after 6 h of in vitro incubation, and more than 8 x 10(2)-fold 6 h after intramammary infusion. In vitro growth in milk was not associated with in vivo growth during the early phase of infection, nor with severity of E. coli mastitis. Somatic cell count before experimental E. coli mastitis was negatively associated with in vivo bacterial growth during the early phase of infection (R2 = 0.28), but was not associated with severity of E. coli mastitis (R2 = 0.06). In vivo bacterial growth during the early phase of infection (positive association; R2 = 0.41), together with influx of inflammatory cells in milk, expressed as mean hourly increase of somatic cell count between 6 and 12 h post-infusion (negative association; R2 = 0.11), are major determinants for the severity of experimental E. coli mastitis (R2 = 0.56).  相似文献   

15.
This study compared the different leucocyte populations in milk from udders infected with different mastitic pathogens and in different stages of infection. Milk samples were collected from quarters free of intramammary infection, acutely infected with Escherichia coli or Staphylococcus aureus and chronically infected with S. aureus, coagulase-negative staphylococci (CNS) or Streptococcus dysgalactiae. Udder bacteriological status was confirmed after three consecutive bacteriological examinations from weekly quarter milk samples. At the time of the trial, milk samples were tested for somatic cell count (SCC) and differential cell count by both light microscopy (LM) and flow cytometry. Monoclonal antibody (mAb) CD11a/CD18 was used in order to differentiate between leucocytes and epithelial cells when tested by flow cytometry. Udder quarters free of intramammary infection had a mean SCC lower than 107 x 10(3) cells/ml in which the epithelial cells were the main cell type followed by polymorphonuclear cells (PMNs), while macrophages and lymphocytes had a lower concentration. Only 56% of the cells were labelled with the mAb anti-CD11a/CD18. In either acute E. coli- or S. aureus-infected quarters, SCC were significantly higher (P < 0.0001) than in samples from the time of inoculation, with over 90% of the cells labelled with the mAb anti-CD11a/CD18. The main cell type was neutrophils. In chronically infected cows, differences in SCC and in leucocyte patterns were found between infecting pathogens as well as between quarters harbouring the same pathogen. In all the chronically infected quarters, SCC was significantly higher (P < 0.05) than in uninfected ones. The distribution of the leucocyte patterns in the quarters infected with S. dysgalactiae did not differ from that in quarters with acute infection with both E. coli and S. aureus. In the cows chronically infected with S. aureus or CNS, the proportion of PMN was higher but not significantly different from quarters free of intramammary infection, while epithelial cells were significantly lower (P < 0.05). The T lymphocytes bearing CD4+ or CD8+ were significantly higher in quarters chronically infected with S. aureus than in quarters free of intramammary infection and in quarters acutely infected with either E. coli or S. aureus. In all samples B cells were negligible.  相似文献   

16.
Bacteriological quality of raw cow's milk taken at different sampling points from four dairy farms and a milk collection centre in and around Addis Ababa was evaluated. Milk samples were aseptically collected from udder, bucket, storage container before and after cooling and upon arrival at the processing plant. A high increase in the mean total aerobic plate count was observed in milk samples taken from the bucket (1.1 x 10(5) cfu/ml), storage container before cooling (4 x 10(6) cfu/ml) and upon arrival at the processing plant (1.9 x 10(8) cfu/ml). The mean coliform counts ranged from 1.3 x 10(4) cfu/ml (storage container before cooling) to 7.1 x 10(4) cfu/ml (upon arrival at the processing plant). The hygienic quality of raw milk from the collection centre was poor with a mean total bacterial count of 1.3 x 10(7) cfu/ml. Milk sampled from the udder contained mainly staphylococci and micrococci as udder-specific bacteria, while samples taken at later stages were additionally contaminated with bacteria of environmental origin (especially Enterobacteriaceae). Lack of knowledge about clean milk production, use of unclean milking equipment and lack of potable water for cleaning purposes were some of the factors which contributed to the poor hygienic quality of raw milk in the study farms.  相似文献   

17.
This study was conducted to investigate the normal somatic cell count (SCC) and to define subclinical mastitis in Murrah buffaloes. Data were collected from 60 clinically normal buffaloes stationed at five farms of Chitwan Nepal and Buffalo Research Center, Hissar, India. Somatic cell count was measured using the Newman-Lampert staining technique. The upper limit of SCC was determined >or=200 000/ml of milk based on the mean +/- 2SD of a total SCC. Abnormal data of the SCC was repeatedly removed, which lie beyond the values of more than mean + 2SD until all the data come to lie within (mean + 2SD). Averages of SCC of right front and right hind quarters were significantly higher than left front and left hind quarters. Nearly 94% of California mastitis test (CMT) negative quarters were having somatic cells >or=200 000/ml. The mean SCC of CMT positive quarter was significantly higher (P < 0.01) than CMT negative quarters. Subclinical mastitis was diagnosed on the basis of samples with SCCs >or=200 000/ml with positive bacterial cultures. Subclinical mastitis was found in 21.7% buffaloes and 8% of the quarter foremilk samples. Neutrophil counts were significantly higher in subclinical mastitis milk.  相似文献   

18.
Individual cow somatic cell count (SCC) patterns were explored over a one year period in 33 dairy herds to investigate the reason for a summer rise in bulk milk somatic cell counts (BMSCC). Cow test day somatic cell counts were categorised according to the magnitude of change since the previous test day reading, to examine which categories were responsible for the summer increase. Multilevel models using Markov chain Monte Carlo methods were specified to estimate the number of somatic cells/ml produced by different cell count categories. Stage of lactation and parity were accounted for in the models. There was an increase in the proportion of cows that remained above 200,000 cells/ml for two consecutive recordings in summer and this group of cows were responsible for 70.8% of the increase in somatic cells/ml produced from May to September compared with October to March. There was no evidence that a greater new infection rate (somatic cell counts moving from below 100,000 cells/ml to over 200,000 cells/ml) contributed to the increased summer bulk milk somatic cell counts. There was no indication that a general small increase in all somatic cell counts played an important role in the increased summer somatic cell counts. Markov chain Monte Carlo methods provided a valuable and flexible platform for parameter estimation in reasonably complex multilevel models.  相似文献   

19.
A cross-sectional survey of 523 dairy farms in the south of Chile was carried out to quantify risk factors associated with bulk-milk somatic-cell count (BMSCC) >200 x 10(3)cells/ml.Questionnaires followed by one reminder were sent to 3710 dairy farms via the 11 milk-processing plants that they supplied in October 1998. The response proportion was 14.1%. The median BMSCC was 289 x 10(3) cells/ml (range: 74 x 10(3) to 1800 x 10(3)cells/ml). The median herd size was 70 cows (range: 7-616); herd size was not associated with BMSCC. The annual milk yield of 33.2% of the herds was <4000 l and 53.4% had an annual milk yield of 4 x 10(3) to 6 x 10(3) l. Clinical-mastitis records were kept by 55.3% of the farmers. Seventy-six percent of the farmers (377/499) reported <10 clinical cases of mastitis in the year prior to the questionnaire.Logistic multiple regression indicated that BMSCC >200 x 10(3)cells/ml was more likely when foremilking was practised, and when cows were collected in a yard before milking. BMSCC was less likely to be >200 x 10(3)cells/ml when teats were washed with water containing disinfectant compared with plain water; when the udder and teats were always checked before milking compared with, sometimes or never; when cows with mastitis were milked first compared with any other ordering, and when farmers recorded individual-cow somatic-cell count (ICSCC) compared with when ICSCC was not recorded.  相似文献   

20.
Listeria monocytogenes was isolated from the milk of two cows and two sheep with mastitis in one quarter and one udder half. The animals were observed over a period of 2-12 months. Clinical examination of the udder, bacteriological examinations and determination of somatic cell counts of milk samples were performed monthly. All four cases suffered from a subclinical mastitis characterized by an elevated somatic cell count (0.8-10.1 x 10(6) cells/ml), a persistent shedding of Listeria and by a normal appearance of the milk. The animals did not show any systemic reaction, but all animals developed an atrophy of the infected mammary gland. Histological examinations revealed a chronic interstitial mastitis with diffuse infiltration of lymphocytes, plasma cells and macrophages. All internal organs showed no abnormalities, no Listeria could be isolated. Listeria could however be isolated from the affected mammary parenchyma and from the mammary lymph node. The results of the bacteriological examination could be confirmed by means of PCR. Using PFGE, all the isolates from the same animal were identical. Immunohistochemical examination of the ovine mammary glands achieved a very strong immunoreactivity for CD5 cells. The mode of infection and the reaction of the immune system's defense of the ovine udders are discussed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号