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1.
Summary The effect of intramammary injection of recombinant bovine interleukin-8 (rbIL-8, 1 mg/10 ml of saline) on quarter milk levels of somatic cell count (SCC), chemiluminescence (CL) activity and counts of total bacteria and Staphylococcus aureus (S. aureus) was investigated, using 10 Holstein cows with an early stage or a late stage of subclinical mastitis naturally infected with S. aureus. In the late-stage group, milk SCC and CL activity had significant rises with maximum levels at 6 h, following maintained high levels thereafter post-cytokine injection. The counts in milk total bacteria and S. aureus were insignificantly decreased, being increased back on day 7 post-cytokine injection. Thus, the cytokine was inefficient for the late-stage subclinical mastitis. However, in the early-stage group milk SCC and CL activity declined to under pre-injection levels on day 7 after marked and significant rises at 6 h and day 1 post-cytokine injection. The milk total bacterial count decreased significantly on days 0.25 and 2. Furthermore, the milk S. aureus count was decreased significantly on days 1, 2, 3 and 7 by the cytokine injection. These results suggest that the rbIL-8 has a potential as a therapeutic agent of the subclinical mastitis of dairy cows, if the cytokine is applied at an initial stage of infection.  相似文献   

2.
The effect of intramammary injection of recombinant bovine interleukin‐8 (rbIL‐8, 1 mg/10 ml of saline) on quarter milk levels of somatic cell count (SCC), chemiluminescence (CL) activity and counts of total bacteria and Staphylococcus aureus (S. aureus) was investigated, using 10 Holstein cows with an early stage or a late stage of subclinical mastitis naturally infected with S. aureus. In the late‐stage group, milk SCC and CL activity had significant rises with maximum levels at 6 h, following maintained high levels thereafter post‐cytokine injection. The counts in milk total bacteria and S. aureus were insignificantly decreased, being increased back on day 7 post‐cytokine injection. Thus, the cytokine was inefficient for the late‐stage subclinical mastitis. However, in the early‐stage group milk SCC and CL activity declined to under pre‐injection levels on day 7 after marked and significant rises at 6 h and day 1 post‐cytokine injection. The milk total bacterial count decreased significantly on days 0.25 and 2. Furthermore, the milk S. aureus count was decreased significantly on days 1, 2, 3 and 7 by the cytokine injection. These results suggest that the rbIL‐8 has a potential as a therapeutic agent of the subclinical mastitis of dairy cows, if the cytokine is applied at an initial stage of infection.  相似文献   

3.
The effect of an autogenous vaccine against Staphylococcus aureus on S. aureus prevalence and mastitis, as well as on somatic cell count (SCC), was studied in a dairy herd with a high prevalence of S. aureus. The vaccination group (n = 35; 22 cows and 13 heifers) and the control group (n = 36; 23 cows and 13 heifers) received the vaccine or a placebo, respectively, according to the following protocol: all animals: basic immunization (twice, 3 weeks apart); cows: booster dose at the time of drying off, 5 and 2 weeks before calculated calving date; heifers: booster dose 2 and 5 weeks before calculated calving date. The vaccine or the placebo was administered subcutaneously in the area of the supramammary lymph nodes. Quarter milk samples were collected monthly and subjected to SCC and bacteriological evaluation. At this time, the animals were also checked for signs of clinical mastitis. Non-clinical S. aureus mastitis diagnoses were based on udder quarter SCC and a positive S. aureus culture. In order to compare the SCC in individual whole milk samples, records from the monthly milk quality testing were evaluated. Cow and udder quarter prevalence of S. aureus intramammary infections calculated for the experimental animals and quarters, respectively, did not differ between groups. However, during the lactation period following the boostcr dose, the prevalence of S. aureus increased in both groups (P < 0.05). The cumulative incidence of various mastitis diagnoses (clinical, subclinical, latent infection) due to S. aureus on an animal basis did not differ between groups. On an udder quarter basis, the cumulative incidence of subclinical mastitis was higher in vaccinated animals than in control animals (33.8 versus 26.0%; P < 0.05). This was mainly due to a higher cumulative incidence of subclinical mastitis in vaccinated than control heifers. The SCC in composite milk samples did not differ between groups, but increased as lactation progressed. The herd prevalence of S. aureus differed considerably throughout the study period, but declined consistently to below 10% at the end of the study period. Recent herd checks revealed a prevalence of S aureus infections of < 5%. It is concluded that the autogenous bacterin tested in this study did not have the desired effect on the prevalence of S. aureus infections and mastitis or SCC. The decline in S. aureus prevalence was very probably due to other factors than specific immunization against S. aureus.  相似文献   

4.
Serum amyloid A proteins (SAA) are very sensitive acute phase proteins, displaying multiple isoforms in plasma and different body fluids. They are currently under investigation as biomarkers of diseases. The aim of the present study was to compare the concentration and isoform expression of SAA in serum and milk of cows with bacteriologically negative milk (control group) and naturally occurring Staphylococcus aureus (S. aureus) subclinical mastitis (subclinical mastitis group). Somatic cell count (SCC) and bacteriological analyses were performed to establish the control and subclinical mastitis group. SAA concentration was evaluated using a commercial ELISA kit, while expression of different isoforms (serum A-SAA and milk M-SAA3 isoforms) was visualized by denaturing isoelectrical focusing and immunoblotting. The SAA concentrations in sera and milk of cows in the subclinical mastitis group were three and 100 times higher than in those from the control group of cows, respectively. Cows in the subclinical mastitis group had more acidic SAA isoforms in serum with the most prominent one at pI 5.5. This isoform was not detected in sera from the control group. Milk samples in the subclinical mastitis group contained abundant highly alkaline M-SAA3 isoforms and most of the serum isoforms, except for that at pI 5.5. In the subclinical mastitis group SAA isoforms with equivalent pI as serum isoforms accounted for 20% of the total SAA concentration in milk. There were significant differences in the concentrations and isoform patterns of SAA in serum and milk between the control and subclinical mastitis groups of cows. Also, we demonstrated that serum SAA isoforms were not transferred to milk proportion to their plasma content.  相似文献   

5.
To evaluate clinical effects of autogenous toxoid-bacterin treatment for Staphylococcus aureus subclinical mastitis in lactating cows, 22 cows which had at least one S. aureus infected quarter were selected from among cows at a S. aureus prevalent dairy farm. Eleven cows were injected with their own autogenous toxoid-bacterin and the others were maintained as non-injected control. In the toxoid-bacterin injected group, 27% of infected quarters were cured during the 12-week trial, compared to 5% in the control group. New intramammary infections with S. aureus were only detected in 3 quarters of the control group. Mean IgG antibody titer against S. aureus somatic antigens and alpha-toxin in serum and milk were significantly increased in the toxoid-bacterin injected group (p<0.05) and remained higher than those of the control group which showed no significant changes (p<0.05). In contrast to the control group, from 3 weeks after the second injection of the toxoid-bacterin injected group, mean S. aureus cfu/ml in milk samples from injected quarters with S. aureus was significantly decreased until the end of the study (p<0.05). In the toxoid-bacterin injected group, significant decreases of mean SCC were detected from milk samples from infected quarters with S. aureus from week 7 to week 10 (p<0.05). These data show that autogenous toxoid-bacterin treatment against S. aureus subclinical mastitis in lactating cows may increase the cure rate of the infections, reduce the severity of the infections and also prevent occurrence of the new infections.  相似文献   

6.
Changes in inflammatory parameters, leukocyte surface markers, functional responses and cytokine mRNA expression of leukocytes of dairy cows with naturally occurring chronic Staphylococcus aureus (S. aureus) mastitis and healthy cows were determined to elucidate the leukocyte responses to S. aureus infection of the mammary gland. Increased values in inflammatory parameters and matrix metalloproteinase activities in milk revealed the characteristics of cows with chronic mastitis. Expression of L-selectin and CD18 molecules on neutrophils and proportion of CD8 cells in milk from cows with S. aureus mastitis were significantly (P<0.05) increased compared with those found in healthy cows. The FcR-stimulated CL response of blood neutrophils was significantly (P<0.05) decreased in cows with S. aureus mastitis. Significantly (P<0.05) decreased mitogenic responses of lymphocytes were found in cows with S. aureus mastitis; however, the values were not restored to those of healthy cows when stimulated with both mitogens and the cytokine IL-1β. The mRNA expression of TNF-α, IL-1β and IL-8 on milk leukocytes from cows with S. aureus was found to be increased compared with that of healthy cows. The changes of immune responses found in cows with S. aureus mastitis appear to be influenced by the severity and duration of inflammation in infected quarters. The down-regulation of the leukocyte functions found in cows with S. aureus mastitis appears to be associated with the progress of the chronic stage of S. aureus mastitis.  相似文献   

7.
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   

8.
The effect of rbGM-CSF intramammary infusion on the subclinical mastitis was evaluated by the somatic cell count (SCC) and expression of adhesion molecules (CD62L and CD11b) on the surface of neutrophils (PMN) in blood and milk. Fifteen cows diagnosed to have subclinical mastitis were used in this study. Seven cows showed a decrease in the SCC (decreased group), whereas 8 cows showed an increase in the SCC (increased group) 7 days after infusion of rbGM-CSF compared to pre infusion level. The percentage of CD62+ cells tended to be lower and CD11b+cells tended to be higher at 6 h on blood PMN in the decreased group of cows. Increased group of cows showed opposite tendencies. The mean fluorescent intensity of these adhesion molecules expressed on PMN in blood and milk was similar in both groups. These results suggested some association between expression of adhesion molecules and changes in SCC by rbGM-CSF. Responsiveness of PMN adhesion molecules to rbGM-CSF might determine the changes in SCC of the subclinical mastitic cows after infusion of rbGM-CSF.  相似文献   

9.
Cows with subclinical mastitis caused by Staphylococcus aureus were subjected to subcutaneous injections with either an extract from the root of Panax ginseng CA Meyer at a dose of 8 mg/kg body weight per day for 6 days, or with saline as a control. The injection areas were checked for adverse reactions. The daily milk production was measured before and after treatment. Blood was collected for total and differential leucocyte counts, identification of lymphocyte subpopulations using flow cytometry, lymphocyte proliferation test, and neutrophil phagocytosis and oxidative burst assay. Quarter milk samples were collected for bacteriological analysis and somatic cell counts (SCC). After the end of treatment, the numbers of S. aureus-infected quarters and milk SCC tended to decrease in ginseng-treated cows. Phagocytosis and oxidative burst activity of blood neutrophils were significantly increased 1 week after ginseng treatment, but the proliferative response of blood lymphocytes did not change significantly. The number of monocytes in ginseng-injected cows was significantly higher 1 week post-treatment than pre-treatment, and the number of lymphocytes was significantly higher than pre-infusion at 2 and 3 weeks after ginseng treatment. Similar changes were not observed in the control group. The present findings indicate that ginseng treatment can activate the innate immunity of cows and may contribute to the cow's recovery from mastitis. It is therefore suggested that ginseng has a potential as a stimulator of the immune system of dairy cows.  相似文献   

10.
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.  相似文献   

11.
Zhen YH  Jin LJ  Li XY  Guo J  Li Z  Zhang BJ  Fang R  Xu YP 《Veterinary microbiology》2009,133(4):317-322
The objective of this study was to estimate the efficacy of specific egg yolk immunoglobulin (IgY) to bovine mastitis caused by Staphylococcus aureus. Eighteen lactating cows with clinical mastitis and 18 lactating cows with experimental mastitis (1 quarter per cow) were randomly assigned to three treatments: IgY (20mg/ml) infusion, penicillin (100mg/ml) infusion and no infusion. Treatments for clinical mastitis and experimental mastitis were performed by a 6-day course of intramammary infusion with a dosage of 10ml at an interval of 12h. Milk samples were collected at morning milking time for testing color, clot, somatic cell counts (SCC) and bacterial count. For most of the cows treated with IgY and penicillin, the milk color and clot recovered to normal form during the therapy course. The milk SCCs and bacterial counts of treated cows decreased compared to those of untreated cows (p<0.05). The cure rates by IgY for experimental and clinical mastitis were 83.3% and 50%, respectively, and those by penicillin were 66.7% and 33.3%, respectively. These results showed the potential of specific IgY to be an alternative therapy for mastitis caused by S. aureus.  相似文献   

12.
The aim of this study was to investigate total antioxidant (TAC), and oxidant capacity (TOC) and nitric oxide (NO) levels in milk of cows with subclinical mastitis. Brown Swiss and Holstein breed cows were screened with California Mastitis Test (CMT) to determine mammary glands with subclinical mastitis. Moreover, somatic cell counts (SCC) were determined electronically in all milk samples. Mammary quarters were classified as healthy (n = 25) or subclinical mastitis (n = 35) based on CMT scores and somatic cell count (SCC: ?200,000/ml or >200,000/ml) in milk. Nitric oxide, TOC and SCC levels were significantly higher (p < 0.001, p < 0.005 and p < 0.001, respectively) in milk from mammary quarters with subclinical mastitis compared to those from healthy mammary quarters. In conclusion, subclinical mastitis results in higher NO concentrations, TOC and SCC, and NO and TOC were positively correlated with SCC. Moreover, alterations in NO levels and TOC in milk could be used as an alternative diagnostic tool to screen for subclinical mastitis.  相似文献   

13.
Polymorphonuclear neutrophil (PMN) function changes during mastitis. To investigate the contribution of milk PMN to the severity of Escherichia coli (E. coli) mastitis, chemiluminescence (CL) of blood and milk PMN and their efficiency to destroy coliform bacteria in the mammary gland were examined following the induction of E. coli mastitis in early lactating cows. To better assess and define the degree of mastitis severity, cows were classified as moderate and severe responders according to milk production loss in the non-infected quarters at post-infection hour (PIH) 48. There was an inverse relationship between pre-infection milk PMN CL and colony-forming units at PIH 6. In moderate cows, the pre-infection blood and milk PMN CL was approximately 2-fold higher than that of severe cows. The probability of severe response increased with decreasing pre-infection PMN CL. At the beginning of the infection blood and milk PMN CL was consistently higher, and milk PMN CL increased faster after infection in moderate cows. At PIH > 48 milk PMN CL in severe cows exceeded that of moderate cows. The somatic cell count (SCC) in moderate cows increased faster than colony-forming units, whereas in severe cows the results were reversed. The kinetics of CL activity for blood and milk PMN before and during the early phase of infection confirmed an impairment in PMN CL activity for severe responding cows. High pre-infection blood and milk PMN CL and the immediate increase of milk PMN CL and SCC after infection limited bacterial growth thereby facilitating the recovery of E. coli mastitis in moderate cows. Our study strengthens the idea that pre-existing milk PMN (a static part of the udder's immune defense) functions as a "cellular antibiotic" before and during infection, and low milk PMN CL is a risk factor for bovine coliform mastitis.  相似文献   

14.
作者针对临床及亚临床乳房炎奶牛乳汁中金黄色葡萄球菌分离株的毒素基因进行检测和脉冲场凝胶电泳(PFGE)基因分型,比较2种类型乳房炎金黄色葡萄球菌分离株的差异.无菌法采集奶样,采用国际标准方法从中分离金黄色葡萄球菌,用多重PCR方法扩增nuc基因和mecA基因以确证金黄色葡萄球菌(SA)和耐甲氧西林金黄色葡萄球菌(MRSA).进一步用PCR方法检测SA的各种毒素基因(SEs、ETs、TSST 1和PVL基因等).利用限制性内切酶Sma Ⅰ对SA基因组DNA进行酶切和PFGE分析,最后利用BioNumerics软件进行聚类分析.结果:19.3％(23/119)的临床乳房炎奶样和14.8％(26/176)的亚临床乳房炎奶样确定为金黄色葡萄球菌阳性样品,分别从中分离鉴定出43株和26株金黄色葡萄球菌,其中临床乳房炎分离株中有5株为mecA基因阳性.临床乳房炎奶牛奶样中检测到SA的SEA、SEB、SED、SEJ和PVL毒素基因,检出率分别为3.8％(1株)、11.5％(3株)、19.2％(5株)、7.7％(2株)和31.2％(10株);亚临床乳房炎奶牛乳样中仅检测到SA的SEA和PVL毒力基因,检出率分别为7.0％(3株)和84.1％(37株).表明临床与亚临床乳房炎奶牛乳汁中SA菌株携带的毒素基因不一样,SEs可能是临床乳房炎菌株的重要致病基因,PVL可能是亚临床乳房炎菌株的重要致病基因.69株SA使用Sma Ⅰ酶切分型后,可分为7个大簇、50个基因型,来源相同的SA分型后大部分位于同一簇内.临床乳房炎奶牛乳汁中检测到MRSA菌株,PVL基因在亚临床乳房炎中的检出率为临床乳房炎的2.7倍.PFGE方法能较好的区分临床乳房炎和亚临床乳房炎的SA分离菌株.  相似文献   

15.
在对山东7个地区14个奶牛场临床型和隐性乳腺炎调查的基础上采集234头临床乳腺炎病牛乳样、241个隐性乳腺炎乳样并分别做了细菌学检查,结果表明:泌乳期临床型乳腺炎病原菌以凝固酶阴性葡萄球菌、金黄色葡萄球菌、链球菌、酵母菌和棒状杆菌为主;干奶期临床型乳腺炎病原菌以大肠杆菌、链球菌、金黄色葡萄球菌、凝固酶阴性葡萄球菌和酵母菌为主;隐性乳腺炎病原菌以凝固酶阴性葡萄球菌、金黄色葡萄球菌链球菌、酵母菌、假单胞菌和棒状杆菌为主;厌氧菌在隐性乳腺炎、干奶期乳腺炎和干奶期乳腺炎乳样的捡出率分别为 5．82％,4．17%,10．16％;隐性乳腺炎、干奶期乳腺炎细菌的共感染率较高,与泌乳期乳腺炎病原菌的差异极显著(P<0．01),隐性乳腺炎与干奶期乳腺炎病原菌共感染率差异不显著(P >0．05)。  相似文献   

16.
The efficacy of two dry cow treatment (DCT) regimens for subclinical Staphylococcus aureus mastitis was evaluated in naturally infected dairy cows. At dry-off, cows were assigned to two treatment groups by randomized blocks on the basis of parity and somatic cell count (SCC). Two antibiotic DCT regimens were used, namely: (1) a single intramammary infusion containing sodium nafcillin, procaine benzylpenicillin and dihydrostreptomycin; and (2) systemic cefquinome administered intramuscularly, twice at a 24-h interval. In the intramammary (IMM) treatment group, the S. aureus intramammary infection (IMI) rate was reduced from 40% (56/140 quarters) before dry-off to 20% (28/140) after calving. Seventy per cent (39/56) of the S. aureus-positive quarters were negative after calving, and 13% (11/84) of the negative quarters were positive after calving. In the systemic treatment group, the S. aureus IMI rate increased from 39% (29/74 quarters) before dry-off to 55% (41/74) after calving. Twenty-eight per cent (8/29) of the S. aureus-positive quarters were negative after calving and 45% (20/45) of the negative quarters were positive after calving. The odds ratio of an S. aureus-positive quarter being negative after calving in the IMM group relative to the systemic therapy group was 44.6 (95% confidence interval = 2.1-909.1, P < 0.01). Parity, quarter, milk SCC and N-acetyl-beta-D-glucosaminidase were tested in the model, and were found to have no significant effect on S. aureus cure rates or new IMI rates. The IMM treatment resulted in a higher cure rate compared with that observed in previous studies. The very low cure rate after systemic cefquinome treatment was comparable to the spontaneous cure rate observed in untreated controls in previous studies. The unfavourable results of the cefquinome systemic DCT might reflect inadequate pharmacokinetic properties of the drug regarding poor udder penetration in subclinical mastitis and short antimicrobial effect compared with the IMM treatment.  相似文献   

17.
The abundance of milk cathelicidin proteins during bovine mastitis   总被引：1，自引：0，他引：1  
Current on-farm methods for detecting mastitis in dairy cows have limitations with their specificity and sensitivity, particularly at an early stage of infection. There is therefore a need to explore new approaches for detecting early and subclinical mastitis. This study examined the expression of a group of neutrophil-specific proteins, the cathelicidins, in milk samples from naturally occurring as well as experimentally induced mastitis infections. Immunoblot analysis indicated that cathelicidin proteins are only observed in infected quarters and demonstrate a high correlation with somatic cell count (SCC) during the onset of infection. In most of the infections examined, cathelicidin was detected prior to the observation of clinical symptoms and at SCC counts as low as 6.2 × 10(3)cells/mL. In naturally occurring mastitis the correlation between cathelicidin and infection status is not as strong, with 25% of pathogen-positive milk samples containing no detectable cathelicidin. This may reflect the varying levels of neutrophil concentration and activity at different stages or severities of infection. Our results indicate that milk cathelicidin levels increase following intramammary infection and cathelicidin-based biomarkers may assist in the detection of preclinical mastitis or determining the stage of infection.  相似文献   

18.
Staphylococcus aureus is recognized worldwide as a pathogen causing many serious diseases in humans and animals, and is the most common aetiological agent of clinical and subclinical bovine mastitis. The importance of evaluating the combination of S. aureus virulence factors has been emphasized both in human and veterinary medicine, and knowledge about the genetic variability within different S. aureus populations would help in the design of efficient treatments. The aim of the present study was to determine the genetic profiles of S. aureus strains isolated from milk of cows suffering from clinical and subclinical mastitis in Belgium. The presence of about forty virulence-associated genes was investigated by specific polymerase chain reaction (PCR) amplification. A high number of genotypic subtypes were observed, demonstrating further the large variation in the presence of virulence genes in S. aureus isolates and the considerable diversity of strains populations that are able to cause mastitis in cows. In accordance with other studies, we showed that some genes are associated with mastitis-causing S. aureus isolates, whereas others are absent or rarely present. We also further highlighted the presence of conserved gene combinations, namely the enterotoxigenic egc-cluster and the bovine pathogenicity island SaPIbov. Importantly, the presence of isolates carrying genes coding for toxins involved in important human infections makes the milk of cows with mastitis a potential reservoir for these toxins, and therefore a potential danger in human health, which strengthens the importance to consider raw milk consumption and its processing very carefully.  相似文献   

19.
The purpose of the study was to estimate the extent to which one quarter could be inflamed relative to the other three quarters of a cow, given that knowledge only of the composite milk somatic cell count (SCC) was available. An algebraic relationship, which incorporated the parameters of composite milk SCC, production loss associated with composite milk SSC, SCC of milk from an inflamed quarter, and SCC from three non-inflamed quarters, was used to derive hypothetical estimates of the SCC in one inflamed quarter. A simple case was considered in which one quarter was mastitic, the SCC in milk of the noninflamed quarters was equal, and there was no production compensation by the noninflamed quarters. Previously published estimates were used for production loss associated with composite milk SCC. For moderate composite milk SCC (300,000-500,000 cells/mL) and low-to-moderate SCC in milk of noninflamed quarters (100,000 cells/mL), the SCC of milk from one inflamed quarter was predicted to be very high, ranging from about 1.26 million (log10 SCC = 6.1) to 6.3 million (log10 SCC = 6.8) cells/mL, and compatible with signs of clinical mastitis. These results suggest that in order to screen cows with clinical mastitis in only one quarter, composite milk SCC should be considerably lower than values presented previously by other investigators.  相似文献   

20.
A placebo-controlled field study was performed to evaluate the effect of a herd-specific vaccine against Staphylococcus aureus on intramammary infection (IMI), somatic cell count (SCC) and clinical mastitis. Three hundred and twenty-one heifers were assigned to two groups. Heifers in the vaccination group (n = 164) were vaccinated twice, i.e. 5 and 2 weeks before their expected calving date. Animals of the control group (n = 157) received the same treatment with a placebo containing no bacterial antigen. Quarter milk samples were collected immediately after parturition prior to the first machine milking, 3-4 weeks after calving and before the onset of treatment in animals with signs of clinical mastitis during the first 3 months after calving. For comparison of SCC the data from the monthly milk test records were evaluated. The prevalence of S. aureus in quarter milk samples taken at calving and 3-4 weeks post-partum did not differ significantly between the vaccine and control group. Incidence of clinical mastitis during the first 3 months after calving and the prevalence of S. aureus in quarter milk samples taken before the onset of treatment did not differ significantly between the groups. The SCC was lower in vaccinated than in control heifers. However, the difference was only significant on the third milk test day. Regarding prevalence of IMI with S. aureus and incidence of clinical mastitis the use of a herd-specific vaccine against S. aureus did not prove to be efficient on this farm.  相似文献   

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