奶牛隐性乳房炎发病因素的研究

[目的]为了探讨奶牛隐性乳房炎的影响因素。[方法]以2009年1月至2010年1月五个大型奶牛场的5080头泌乳荷斯坦牛为试验材料,从年龄、胎次、日泌乳量、乳区等方面对其隐性乳房炎发病情况进行了调查、统计和分析,并随机选取50头患隐性乳房炎的病料,进行病原学检查。[结果]表明,试验牛群中8.5%的荷斯坦牛为临床性乳房炎阳性,45%的荷斯坦牛为隐性乳房炎阳性;并且,随着年龄、胎次、日泌乳量的不断增加,荷斯坦牛患乳房炎的几率增加;左侧乳区发病率高于右侧乳区;后侧乳区高于前侧乳区;隐性乳房炎的病原微生物主要以金黄色葡萄球菌为主。[结论]加强日常卫生管理是减少乳房炎发病的主要手段。     

Immunobiology of bovine mammary gland: apoptosis of somatic cells in milk during naturally occurring mastitis

Mastitis remains a major cause of economic losses in dairy herds. It is believed, that the enhancement of natural defense mechanisms in mammary gland may be helpful in the treatment of bovine mastitis. Our study was designed to assess the apoptosis of leukocytes isolated from bovine milk during subclinical staphylococcal mastitis. Milk samples were collected from cows naturally infected with one pathogen--Staphylococcus aureus and from animals with mastitis caused by several pathogens, including S. aureus. It has been determined that the rate of apoptosis was lower in mastitic milk, as compared with control samples, although varied significantly between groups. High percentage of apoptotic cells was detected in milk with high counts of pathogenic bacteria. In all groups the rate of apoptosis was dependent on the bacterial load, although various correlations were identified. Thus, it is postulated, that the rate of apoptosis of somatic cells in mastitic milk is related to the etiology of infection and is determined by the bacterial load.     

Enhanced Erythrocytic Lipid Peroxides and Reduced Plasma Ascorbic Acid,and Alteration in Blood Trace Elements Level in Dairy Cows with Mastitis

Oxidative stress has been associated in several inflammatory conditions and incriminated in the pathogenesis of many diseases. However, little information is available on the status of plasma antioxidant levels, essential components of important antioxidant enzymes such as copper, zinc and selenium in blood, and the end product of oxidative damage to the erythrocytic polyunsaturated fatty acids in inflammatory udder conditions. Blood samples were collected from three groups of dairy cows, with 21 in each group: animals with healthy udder, clinical mastitis, and subclinical mastitis. These animals were randomly selected from a herd on the basis of the California mastitis test, somatic cell count and total bacterial count. The mean plasma ascorbic acid concentration was significantly lower in cows with subclinical (p = 0.004) and clinical mastitis (p = 0.000) and the erythrocytic lipid peroxide levels were significantly (p = 0.000) higher in clinical mastitis as compared to controls. There was a significant decrease in mean blood zinc concentration in subclinical (p = 0.005) and clinical mastitis (p = 0.000), but an increase in mean blood copper level in the clinical mastitis group. It was concluded that the blood antioxidant status declines in inflammatory udder conditions, suggesting that incorporation of antioxidants may help in better management of mastitis in dairy cows.     

Treatment for bovine Escherichia coli mastitis – an evidence‐based approach

Bovine mastitis caused by Escherichia coli can range from being a subclinical infection of the mammary gland to a severe systemic disease. Cow‐dependent factors such as lactation stage and age affect the severity of coliform mastitis. Evidence for the efficacy of antimicrobial treatment for E. coli mastitis is very limited. Antimicrobial resistance is generally not a limiting factor for treatment, but it should be monitored to detect changes in resistance profiles. The only antimicrobials for which there is some scientific evidence of beneficial effects in the treatment for E. coli mastitis are fluoroquinolones and cephalosporins. Both are critically important drugs, the use of which in animals destined for food should be limited to specific indications and should be based on bacteriological diagnosis. The suggested routine protocol in dairy herds could target the primary antimicrobial treatment for mastitis, specifically infections caused by gram‐positive bacteria. In E. coli mastitis with mild to moderate clinical signs, a non‐antimicrobial approach (anti‐inflammatory treatment, frequent milking and fluid therapy) should be the first option. In cases of severe E. coli mastitis, parenteral administration of fluoroquinolones, or third‐ or fourth‐generation cephalosporins, is recommended due to the risk of unlimited growth of bacteria in the mammary gland and ensuing bacteremia. Evidence for the efficacy of intramammary‐administered antimicrobial treatment for E. coli mastitis is so limited that it cannot be recommended. Nonsteroidal anti‐inflammatory drugs have documented the efficacy in the treatment for E. coli mastitis and are recommended for supportive treatment for clinical mastitis.     

奶牛隐性乳房炎的检测及其治疗方法

奶牛乳房炎是困扰奶牛养殖业发展最严重的疾病之一,特别是隐性乳房炎,临床症状不明显,不仅导致奶牛产乳量和乳质量的降低,还可能传染给其他奶牛,导致疾病的扩散.因此,只有对乳汁进行检测,通过其生理、生化等指标变化来判断乳房炎的发生情况.为减少该病的发生、提高乳质量,本文总结了奶牛隐性乳房炎的微生物学检验、细胞学检查、酶学指标...     

中草药防治奶牛乳房炎的研究进展

奶牛乳房炎是危害奶牛养殖业常见的疾病之一,尤其是隐性乳房炎对奶牛生产造成了巨大的经济损失,文章对奶牛乳房炎的发病情况和致病机理,传统治疗方法存在的缺点和中草药防治奶牛乳房炎的进展作一综述。     

凉州区奶牛乳房炎主要病原分离鉴定及药敏试验

乳房炎是奶牛最常见的疾病,随着奶牛产业的蓬勃发展,乳房炎已经成为制约该产业的瓶颈之一。从甘肃省武威市凉州区5个奶牛养殖场采集了1 000头荷斯坦奶牛共计3 991份奶样,对临床型和非临床型(隐性)乳房炎分别通过临床症状和兰州隐性乳房炎诊断液(LMT)进行诊断。结果显示:该地区奶牛临床型乳房炎发病率18.20%,亚临床型乳房炎发病率36.50%,总阳性率54.70%,总阳性乳区率54.72%。从阳性奶样中分离纯化得到的主要病原菌为链球菌属、金黄色葡萄球菌和大肠杆菌,且在不同类型乳房炎中的分布情况不同,临床型中链球菌属最多(54.37%),亚临床型中金黄色葡萄球菌最多(48.56%)。对主要病原菌进行药敏试验,结果表明治疗凉州区奶牛乳房炎的最佳药物应为喹诺酮类和庆大霉素类。     

Indicators of inflammation in the diagnosis of mastitis

Mastitis affects the quality of milk and is a potential health risk for the other cows. In a well managed dairy herd, in addition to clinical mastitis, subclinical mastitis should be efficiently detected. Bacteriological sampling is not feasible as a routine test to identify subclinical mastitis, and indirect tests of mastitis are more suitable for selecting cows with intramammary infections for subsequent bacteriological sampling. Mastitis affects the composition of milk, and the degree of changes depends on the infecting agent and the inflammatory response. Indicators of inflammation in the milk which can be determined using rapid, reliable and easy routine techniques, can be used for the early detection of mastitis. The measuring of the somatic cell count in milk is the standard method, but the analysis technique is problematic for routine use in herds. The most promising parameters for monitoring subclinical mastitis are milk N-acetyl-beta-D-glucosaminidase activity, lactose, and electrical conductivity along with some other indicators such as optical and milk flow measurements, preferably with an inter-quarter evaluation included in the test. Acute phase proteins, haptoglobin and serum amyloid A, are also potential candidates for mastitis monitoring. New mastitis detection systems which can be adapted into on-line use are urgently needed, since dairy units are growing bigger and automatic milking systems are being taken into use.     

Diagnosis and treatment of mastitis in mares

Infection and inflammation of the udder (mastitis) is a common condition affecting all domestic mammals, but it appears to be less prevalent in mares than in dairy cows and dairy goats. The seemingly reduced incidence of mastitis in mares can be partially explained by the smaller size and relatively concealed location of the mare’s udder, coupled with a smaller storage capacity than cows and goats. Mastitis can affect lactating, peripartum, dry mares, mares at dry-off or prepubertal foals. Common clinical signs include swollen mammary tissue, abnormal mammary gland secretion, fever and anorexia; less common signs are hindlimb lameness and a swollen mammary vein. On rare occasions, mastitis pathogens can severely affect the nursing foal and mares may develop fibrotic tissue and consequent agalactia in the side(s) or quarter(s) affected. Based on the clinical presentation, mastitis can be classified as acute or chronic, and clinical or subclinical. Diagnosis is based on the clinical signs aided with aerobic culture and cytological evaluation of the gland secretion. In addition, these ancillary tests can also be used to assess prognosis and duration of treatment. Mares suffering from mastitis may present neutrophilia and hyperfibrinogenaemia. Treatment for mastitis includes antimicrobial therapy (systemic and/or locally), nonsteroidal anti-inflammatory drugs, frequent milking and cold hosing with/without hot-packing applied on the gland. While the frequent monitoring of mares after weaning and reducing food intake should be part of common practices at weaning, cleaning of the udder, control of insect populations and frequent milking of mares with a foal unable to nurse can also aid in preventing mastitis.     

新疆垦区奶牛乳房炎致病菌的调查

本试验选取新疆垦区七个试验牛场,临床调查和试剂诊断,检测奶牛712头,采集奶牛乳房炎阳性乳样314份。其中,奶牛隐性乳房炎阳性检出率平均为36.3%,临床性奶牛乳房炎为16.7%;采集阳性奶样经试验分离鉴定,革兰氏阳性菌仍是引起奶牛乳房炎的主要致病菌,但金色葡萄球菌已基本取代链球菌成为主要的致病菌,其检出率为78.98%。另外,常见环境性致病菌如沙门氏菌、大肠杆菌已明显减少,检出率仅为21.1%和9.24%。相反,绿脓杆菌和蜡样芽孢杆菌的检出率明显增加,其检出率为5.41%和11.15%,而且绿脓杆菌和隐球菌已经成为引起临床性乳房炎爆发的两种新的病原,其中隐球菌已经成为造成顽固性乳房炎的又一种新型病原。     

Efficacy of two antibiotic treatments in curing clinical and subclinical mastitis in lactating dairy cows

AIM: To compare the bacteriological and clinical cure rates for clinical and subclinical mastitis in New Zealand dairy cows following treatment with either an intramammary penicillin-dihydrosptreptomycin preparation or a subcutaneous injection of penethamate hydriodide. METHODS: Milk samples were collected from clinical and subclinical cases of mastitis before and 14 and 21 days after initiation of treatment for bacteriological culture, somatic cell count determination and conductivity testing. RESULTS: No significant differences in the bacteriological cure rate of major Gram-positive pathogens, clinical cure rate, somatic cell count or conductivity were found between treatments. However, the bacteriological cure rate of coagulase-negative staphylococcus infections and the overall bacteriological cure rate was lower for quarters treated with penethamate than with penicillin-dihydrosptreptomycin. CONCLUSIONS: The bacteriological cure rate of mastitis caused by major Gram-positive pathogens, the clinical cure rate, somatic cell count and conductivity did not differ between the two antibiotic treatments. .     

宁波市奶牛乳房炎发病及综合防治试验研究

为了解宁波地区奶牛乳房炎发病及主要病原菌构成,采用乳房炎诊断试剂(HMT)对宁波市8个奶牛场307头泌乳牛的1249个乳区进行了隐性乳房炎流行情况调查,采集HMT反应阳性(++)及强阳性(+++)乳区奶样进行细菌分离与鉴定;用纸片扩散法检测主要病原菌对常用抗菌药物敏感性,并选择具代表性牧场进行乳房炎综合防治试验。结果显示,宁波市奶牛隐性乳房炎的头阳性率为71.3%,乳区阳性率为33.5%。主要病原菌的检出率依次为:凝固酶阴性葡萄球菌47.1%、无乳链球菌20.4%、停乳链球菌17.3%、金黄色葡萄球菌5.1%和乳房链球菌3.9%。主要病原菌对青霉素、氨苄青霉素、庆大霉素、复方新诺明和链霉素等药物有不同程度的耐药性,对头孢类及苯唑青霉素敏感。综合防治措施的实施可以明显降低桶奶总细菌数,改善牛奶品质。     

Cromoglycate induces a rebound effect on blood/milk permeability in subclinical mastitis

Chronic subclinical mastitis represents a vicious cycle of constant tissue irritation by bacteria and inflammatory response of the host. Antibiotics have proven relatively inefficient in eliminating chronic mastitic infections. The use of anti-inflammatory agents in mastitis is controversial. Theoretically, the inflammation should not be suppressed as this is a host defence mechanism of the body. However, because it is uncertain whether the infection or chronic inflammation causes more harm to the tissue, there have been efforts to use anti-inflammatory agents such as glucocorticoids and antipyretic analgetics. The problem is that there is insufficient evidence as to which inflammatory mediators (histamine, kinins, prostaglandins, leukotrienes, PAF, interleukin-1 etc.) alone or in combination are important in mastitis.     

Bovine Mastitis: A Survey of Ontario Dairy Producers, 1978

A survey to assess the knowledge and perception regarding mastitis of 1200 randomly selected Ontario dairy producers was conducted using a mailed questionnaire. Other data were provided by the Ontario Milk Marketing Board and the Dairy Herd Improvement Association.

In general, producers were less aware of subclinical than clinical mastitis and did not appreciate the losses in production associated with it. Approximately 40% of producers were not familiar with mastitis in its subclinical form.

Many producers have not adopted practices that have been advocated for the integrated control of mastitis. For example, 35.5% of producers surveyed used single service paper towels and 38% regularly used teat dips and dry cow antibiotic therapy.

     

Mouse models to study the pathogenesis and control of bovine mastitis. A review

Mastitis is a major infectious disease affecting high yielding cows in dairy herds. Because of its economic impact and due to the animal welfare policy, the pathogenesis of this intramammary infection was studied extensively over the past 50 years. Still, the costs associated with the use of dairy cows for mastitis research constitute a major drawback. As an alternative, a mouse model of experimentally induced mastitis was developed some decades ago. This model has been increasingly used as it appears to be very suited for studying ruminant mastitis due to similarities between mice and cows. The various techniques for inducing mastitis in mice as well as the different pathogens and initial inoculum doses used are also compared in this review. Moreover, recent findings concerning the administration of antimicrobial and immunomodulatory agents are discussed. In addition, information is provided on the most novel approaches for the study of mastitis including the use of mutant pathogen strains and transgenic mice.     

B‐Mode and Doppler Sonography of the Mammary Glands in Dairy Goats for Mastitis Diagnosis

This study aimed to evaluate the sonographic characteristics of the udder and teats and to determine the Doppler indexes of mammary artery in healthy and undergoing subclinical and clinical mastitis goats. Thirty animals among Saanen and Alpine Brown goats were arranged in three groups, healthy goats (HG), goats with subclinical mastitis (SMG) and goats with clinical mastitis (CMG). Using the B‐mode, the sonographic characteristics (echotexture and echogenicity) and biometry (diameter and area of the udder cistern, diameter and area of the teat cistern and thickness of the teat wall) were evaluated. Using Doppler ultrasonography, the vascular indexes of the mammary artery were obtained. It was observed hyperechogenicity with solid component in the gland cistern when comparing animals with clinical mastitis and healthy mammary tissue. Regarding the echotexture of the breast tissue, there was heterogeneity in the mammary parenchyma on the three groups, for the milk, it was observed homogeneity for animals on HG and SMG and heterogeneity for animals on CMG. Grey‐scale quantitative assessment revealed increase in echogenicity (mean value) for all the structures when comparing the three groups. Biometry did not reveal statistical difference between groups, for none of the evaluated structures. Doppler examination of the mammary artery showed the decrease of end diastolic velocity and raise of pulsatility index between groups. The association of B‐mode and Doppler ultrasonography is useful for the evaluation of the udder of dairy goats with mastitis. It is a sensitive and specific method for the study of this disease. Doppler mode was unable to establish reliable criteria for diagnosis of subclinical mastitis. Moreover, the quantification of echogenicity is a useful technique for the evaluation of the milk in animals with mastitis; therefore, it is suggested that it can be used as complementary technique for the diagnosis of mastitis in goats.     

New Strategies to Prevent Mastitis

Bovine mastitis remains as the disease causing the biggest economic losses to the dairy industry, despite the intensive research and prevention measures at herd level carried out for decades. Antibiotics are widely used to combat mastitis, but focus should be shifted from treatment to more economical and efficient prevention. The bacteriological aetiology of mastitis has changed from contagious to environmental pathogens, which has reduced the efficacy of the traditional mastitis control strategies. Considerable progress in the understanding of epidemiology, immunology, diagnostics and pathogenesis of mastitis has been made. The modern molecular biological methods offer good possibilities for the research of the epidemiological and virulence aspects of bacteria, which may help in building‐up specific mastitis control strategies for dairy herds. Studies on the host response and relationship between somatic cell count and susceptibility to mastitis offer tools for genetic improvement of dairy cows. Biotechnological approaches for mastitis prevention are in the developmental stage, but many problems are associated, e.g. with vaccination of dairy cows against mastitis. Different methods of immunomodulation for the prevention of mastitis have shown promise in experimental trials, but the evidence is not yet enough to support commercial applications. Improving nutrition, housing and environment of dairy cattle are still crucial in the prevention of mastitis, especially during the most susceptible period after parturition. New milking techniques including robotic milking may provide better possibility for proper milking and improved udder health. Mastitis control should be part of the herd health programme in the dairy herds. In this paper, results from recent research and proposals for new prevention strategies in the field of mastitis are reviewed.     

Mastitis pathogens present in bulk tank milk from seven dairy herds in the Waikato region, New Zealand

AIM: To identify and enumerate colony forming units (cfu) of mastitis pathogens in bulk tank milk (BTM) from pasture-fed New Zealand dairy cows in the Waikato region. METHODS: BTM samples from seven seasonal-calving dairy herds in the Waikato region were collected monthly from August to December 2004 (cows calved during July-September). Milk samples were cultured on blood aesculin and MacConkey agar plates for 24 h, and the number of mastitis pathogens identified and counted. RESULTS: Colonies identified in BTM included aesculin-positive streptococci, Staphylococcus aureus, coagulase-negative staphylococci (CNS), and coliforms; counts ranged from zero to >1,000 cfu/ml. Counts>1,000 cfu/ml for total aesculin-positive streptococci, CNS and coliforms were present in 48%, 51% and 11% of BTM samples, respectively. Counts of Staph. aureus ranged from zero to 1,000 cfu/ml, but first appeared in BTM samples only in October. Staphylococcus aureus was repeatedly isolated in BTM from 4/7 farms during the testing period. CONCLUSIONS: Counts of mastitis pathogens in this study appeared high relative to interpretive criteria set by other workers, which may indicate a high prevalence of mastitis risk factors on these farms. Interpretation of results is difficult as aesculin-positive streptococci, CNS and coliforms can be isolated from the environment as well as from cows with clinical or subclinical mastitis. Furthermore, Staph. aureus is inconsistently excreted from infected bovine mammary glands. More extensive study of this method is required in New Zealand to attempt to further validate the interpretation of results of bacterial culture of BTM. CLINICAL RELEVANCE: This method may be used to monitor challenge from mastitis pathogens over time as part of milk quality control programmes. The technique may be of use as a screening test to provide information to veterinarians, affording them the opportunity to have an input into mastitis control on dairy farms in New Zealand.     

Preliminary studies on the prevalence of Mycoplasma bovis mastitis in dairy in cattle in Australia

A highly sensitive and specific PCR (MB-PCR) was used in preliminary studies to detect M. bovis in milk samples to investigate its association with high somatic cell count (SCC), an indicator of subclinical mastitis and one of the factors in down grading the quality of milk. A total of 186 and 167 herds were tested with 43% and 62% of herds positive for M. bovis in Victoria and North Queensland, respectively. The quarter milks from 52 cows with persistently high SCC were tested by MB-PCR and culture to investigate the association of M. bovis with major mastitis pathogens (MMP). M. Bovis was detected in 77% of cows of which 19% alone had M. bovis without any other bacteria, 17% had M. bovis in combination with major mastitis pathogens and 40% had M. bovis in combination with non-major mastitis pathogens. We believe that M. bovis is widespread in dairy cattle and has the potential to produce disease alone or to predispose the udder to disease caused by major mastitis and environmental pathogens. These studies have revealed a hitherto unrecognised high prevalence of M. bovis in dairy cattle in North Queensland and Victoria in Australia. These initial studies also give a clear association between M. bovis and elevated somatic cell counts.     

Acute phase proteins in milk in naturally acquired bovine mastitis caused by different pathogens

The concentrations of haptoglobin (Hp) and serum amyloid A (SAA) and the activity of N-acetyl-β-D-glucosaminidase (NAGase) in milk from 234 cows with spontaneous mastitis caused by different pathogens were measured to assess whether they corresponded with the clinical signs of mastitis and whether there were any differences between pathogens. Ninety-eight of the cows had clinical mastitis and 136 had subclinical mastitis. There were statistically significant positive correlations between the concentrations of SAA and Hp and the activity of NAGase. Significant differences in the concentrations of acute phase proteins and NAGase activity were found in milk from cows with mastitis caused by different pathogens. The highest concentrations of Hp and NAGase were found in cases of mastitis caused by Escherichia coli and Arcanobacterium pyogenes, and the lowest concentrations were from cases of mastitis caused by coagulase-negative staphylococci. Very low SAA concentrations were found in milk from the cases caused by A pyogenes, in contrast to cases caused by other major mastitis pathogens. The median concentration of SAA was over 10 times higher in cases of mastitis caused by E coli than in mastitis caused by other pathogens. There were significant differences in the mean Hp concentration and NAGase activity between clinical and subclinical mastitis. In approximately one-third of the samples, the Hp concentration was below the detection limit, potentially compromising the use of Hp as a mastitis marker.