Microbiological colonisation of bovine teat canal--significance and influencing factors

The teat canal of lactating dairy cattle is of particular importance for the defence of facultative pathogenic and pathogenic microorganisms (e.g., staphylococci) invading the bovine udder. Furthermore the canal is usually colonized with microorganisms, too. In addition to microorganisms inhibiting mastitis pathogens the teat canal is colonized by staphylococci. The microbial colonization can be influenced by the environment of the animals, the care and disinfection of the teat skin and indirectly by the effects of forces being associated with machine milking. Because of vacuum fluctuations occurring under the teat tip microorganisms, which colonize the teat canal, can invade the bovine mammary gland and cause infections there. This paper gives a review of the microbial colonization of the bovine teat duct and of influencing factors on the microbial populations as well as of the significance of the teat canal colonization for the development of mastitis.     

Mastitis in Post-Partum Dairy Cows

Transition from the dry period to lactation is a high risk period for the modern dairy cow. The biggest challenge at that time is mastitis. Environmental bacteria are the most problematic pathogens around parturition. Coliforms are able to cause severe infections in multiparous cows, and heifers are likely to be infected with coagulase-negative staphylococci. During the periparturient period, hormonal and other factors make the dairy cows more or less immunocompromised. A successful mastitis control programme is focused on the management of dry and calving cows and heifers. Clean and comfortable environment, proper feeding and adequate supplementation of the diet with vitamins and trace elements are essential for maintaining good udder health. Strategies which would enhance closure of the teat canal in the beginning of the dry period and would protect teat end from bacteria until the keratin plug has formed decrease the risk for mastitis after calving. Dry cow therapy has been used with considerable success. Yet, a selective approach could be recommended rather than blanket therapy. Non-antibiotic approaches can be useful tools to prevent new infections during the dry period, in herds where the risk for environmental mastitis is high. Vaccination has been suggested as a means to support the immune defence of the dairy cow around parturition. In some countries, implementation of Escherichia coli core antigen vaccine has reduced the incidence of severe coliform mastitis after calving.     

Coliform mastitis

Gram-negative bacteria that commonly cause bovine mastitis are classified as environmental pathogens. The point sources of coliform bacteria that cause infections include bedding materials, soil, manure and other organic matter in the environment of cows. Rates of coliform mastitis increase during climatic periods that maximize populations in the environment. The portal of entry into the mammary gland for Gram-negative bacteria is the teat canal. Once in the gland, bacteria must utilize available substrates in the mammary secretion to replicate and evade host defenses. Rates of coliform mastitis are greater during the transitional phases of the non- lactating period than during lactation. The ability to infect the non-lactating gland is directly related to the ability of bacteria to acquire iron from the mammary secretion. The primary host defense against coliform mastitis during lactation is the elimination of bacteria by neutrophils migrating into the gland in response to inflammation. Damage to the host is mediated by the release of endotoxin. The severity and duration of clinical signs associated with coliform mastitis are reduced by the use of core-antigen bacterins.     

Teat canal closure in non-lactating heifers and its association with udder health in the consecutive lactation

Prevention of heifer mastitis is a key element in preventing mastitis. Since pathogenesis of heifer mastitis is not fully understood yet, combating it is arduous. The goal of this study was to examine whether the premature loss of the keratin plug of the teat canal represents an important risk factor for the development of heifer mastitis. 84 dairy heifers (German Holstein) from six high-yielding dairy herds in Northern Germany were examined between March 2005 and June 2006. Each quarter was examined clinically at least three times before calving. If the teat canal of a quarter was open, secretion samples were collected for bacteriological analysis. After calving, four quarter samples were collected during the first lactation. A rapid increase of the proportion of open teat canals was detected in the preparturition period. No teat canals were open till 80 days before parturition, while 60% of the teat canals were open at 60 days before parturition. A time-scheduled infection pattern was observed: during the days 90-61, 60-31, and 30-0 before calving, skin inhabitants (coagulase-negative staphylococci, coryneform bacteria), cow-related, and environment-related microorganisms prevailed, respectively. A total of 77% of intramammary infections encountered at parturition had established previously. No significant association between the duration of open teat canals before calving and the udder health post partum was found. However, the incidence of clinical mastitis during first lactation was influenced largely by the duration of infection ante partum and the mastitis pathogen involved. This study shows that a high proportion of teat canals already opens several months before calving and that opening of the teat canal before calving is an important factor in the aetiology of heifer mastitis.     

Effect of damage to the teat end on the experimental induction of mastitis in dry cows with Corynebacterium pyogenes

The teat ends of 12 dry cows were contaminated with Corynebacterium pyogenes. To determine whether a pre-existing (an)aerobic bacterial infection of the udder was a predisposing factor for a C pyogenes mastitis they included infected and uninfected quarters. Anaerobic bacteria could not be found and mastitis was not induced. When the teats were contaminated with C pyogenes after the teat ends had been injured 30 of the quarters became infected, and anaerobic bacteria were demonstrated in many quarters.     

The association between teat end hyperkeratosis and teat canal microbial load in lactating dairy cattle

Most pathogens that cause bovine mastitis invade the udder lumen through the teat canal. Amino acids and intercellular lipids may support microbial colonisation of the teat canal epithelium by pathogenic microorganisms. The aim of this study was to investigate the association between teat end hyperkeratosis, which is induced by machine milking, and teat canal microbial load. Contralateral teats, which differed in teat end hyperkeratosis scores, were identified in a split-udder experiment. The teat canal's microbial load was evaluated using the wet and dry swab technique. Staphylococcus (S.) aureus, Streptococcus (Sc.) uberis, Escherichia (E.) coli and other coliforms were detected by agar plate cultures. The positive detection of E. coli and the log(10)-transformed E. coli load of a teat canal were significantly associated with the teat end hyperkeratosis score (P<0.05). There were significant differences with respect to positive findings for E. coli, as well as the microbial load of E. coli and Sc. uberis, between the less-calloused and the more-calloused teat of a pair. For S. aureus, no significant associations between hyperkeratosis score and teat canal microbial load were detected. In general, a teat with a highly calloused teat end had an increased teat canal microbial load compared with the contralateral teat, characterised by a lower callosity. The results of the present study indicate that the environmental pathogen load is associated with teat end hyperkeratosis. Further research is needed to identify factors that may affect teat canal microbial load in lactating dairy cattle.     

Basic Concepts of the Bovine Teat Canal

The bovine teat canal is highly specialized in its unique function of preventing both leakage of milk and entry of bacteria and thereby plays a major role in the defence of the udder against mastitis. The teat canal is a longitudinally folded cylinder-shaped body opening, covered with approximately the same type of epithelia as the normal skin and surrounded with a net-like integrated musculoelastic system facilitating its opening and closure. During milking, dead, flattened, enucleated squamae (cellular detritus) are sloughed from the teat canal surface and are continually replaced by inner cells differentiating outwards. The epidermis is characterized by a polarized pattern of epithelial growth and differentiation, with a single layer of proliferating keratinocytes and multiple overlying differentiated layers. Morphologically, the cells transit from the basal layers on the basement membrane of the dermis through stratum corneum before they finally end up as the keratin of the teat canal. The majority of the epidermal protein synthesizing machinery is devoted to making keratin. This is reflected in the fact that keratins are the major structural proteins, constituting up to 85% of a fully differentiated keratinocyte. Epidermal keratin is a 40-70 kDa alpha-helical coiled-coil dimer of the intermediate filament family that, among other marker proteins, characterizes each stage of keratinocyte differentiation. Studies of skin fragility disorders show that the primary role of keratins in epidermal cells is to reinforce them so that they do not lyse upon physical pressure and to provide cells with subtly different properties of resistance and plasticity to equip the epithelial cells for the physical stress of each particular body site. Epithelial cell specialization for function also depends, however, on the lipid composition and organization and on the epidermal architecture. Epidermal architecture depends on epidermal turnover time, which in turn depends on cell number as well as the proliferative condition. Both in vitro and in vivo studies have implicated calcium as a major modulator of epidermal differentiation. Calcium is a factor known to enhance differentiation and promote expression of the differentiation-specific keratin genes. In animals and humans, both topical and systemic retinoids produce acanthosis, hypergranulosis and a relative (but not absolute) decrease in the thickness of the stratum corneum. Despite a high degree of epithelial specialization, we expect a somewhat similar immunological functional importance in the teat canal epithelia as in other stratified squamous keratinized type epithelia.     

In vitro growth inhibition of mastitis pathogens by bovine teat skin normal flora.

One factor contributing to differences in the susceptibility of cows to mastitis may be differences in the teat skin normal flora, which could inhibit or enhance the growth of pathogenic bacteria. Using in vitro cross-streaking methods, we found that 25% of the isolates of teat normal flora of non-lactating heifers inhibited the growth of selected mastitis pathogens, but enhancers were not detected. Gram-positive pathogens were inhibited to a greater extent than Gram-negative pathogens. Inhibition was not a characteristic of specific genera or species of normal flora, but rather a property of certain variants within a species. This phenomenon of inhibition of mastitis pathogens in vitro by normal flora may be useful as an in vivo biological control method to reduce the incidence of mastitis.     

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

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

Cytologic observations of the bovine teat end

Cells infiltrating from the vasculature and histologic components of internal tissues of teats (mammary papilla) from noninfected udder quarters were studied, using light and electron microscopy. Morphometric analysis demonstrated a progressive increase in number of infiltrating cells from the distal teat cistern (sinus papillaris) to the junction of the Furstenberg's rosette (distal termination and convergence of mucosal folds lining the teat cistern) and the streak canal (ductus papillaris). Plasma cells contributed to cellular increases in subepithelial connective tissue and were the most prevalent infiltrating cell type. Plasma cells also penetrated the basal epithelial lining of the rosette area and occasionally migrated to the luminal surface near the squamocolumnar junction. Neutrophils and monocytes contributed to the increase in cells infiltrating the epithelial lining. Few infiltrating cells were observed in epithelium and underlying stroma of the streak canal. Cytologic comparison demonstrated a reduction in all cell types from lactating to involuting phases of lactation. Greater numbers of plasma cells, lymphocytes, and monocytes were observed in teat end tissues from quarters previously infected with Staphylococcus aureus.     

Milk flow and udder health in cows after treatment of covered teat injuries via theloresectoscopy: 52 cases (2000-2002)

OBJECTIVE: To determine milk flow, somatic cell counts (SCCs), and the incidence of clinical mastitis in cows that had undergone theloresectoscopy for treatment of teat stenosis caused by mucosal detachment in the region of the streak canal or Fürstenberg's rosette. DESIGN: Retrospective study. ANIMALS: 52 cows with teat stenosis that were treated via theloresectoscopy. PROCEDURE: Medical records of eligible cows were reviewed. Additional data regarding milking ease, SCC, development of clinical mastitis of the affected gland, and whether the cow remained in the herd were collected via owner-completed questionnaires. RESULTS: 49 of 52 questionnaires were completed. At referral, teat sinusitis was diagnosed in 29 of 52 cows. Milk flow was normal in 38 of 41 treated teats at discharge and in 24 of 40 during the next lactation. Thirteen of 49 cows were culled during the next lactation because of abnormal udder health. High SCC and teat sinusitis at referral and development of clinical mastitis during the 10-day period after surgery resulted in high SCCs in the remainder of the current lactation. The incidence of clinical mastitis during the remainder of the current and during the next lactation was higher in cows that had teat sinusitis at the time of surgery, compared with those that did not. CONCLUSIONS AND CLINICAL RELEVANCE: Teat stenoses resulting from mucosal lesions in the region of the streak canal or Fürstenberg's rosette may be successfully treated via theloresectoscopy. Inflammation of the teat sinus and gland at the time of surgery may adversely affect udder health.     

Factors for the genesis of bovine subclinical mastitis

The infection risk of the bovine mammary gland is determined by susceptibility of the cow and contamination and invasion by mastitis pathogens. Genetic (e.g. yield) and lactational physiologic (e.g. stage of lactation) factors support the genesis of subclinical mastitis. This paper considers new data on cow individual and milking related influences on defence mechanisms in the teat end tissue acting in prevention of penetration through the teat canal by mastitis pathogens.     

In vitro growth inhibition of major mastitis pathogens by Staphylococcus chromogenes originating from teat apices of dairy heifers

Earlier field observations suggest that teat apex colonization by Staphylococcus chromogenes pre-partum in dairy heifers protects udder quarters against elevated somatic cell counts early post-partum. To explain these findings, the in vitro inhibitory capability of S. chromogenes from teat apices of heifers towards some major mastitis pathogens was tested using a modified cross-streaking method. Two out of 10 S. chromogenes isolates, both originating from two different teats from the same heifer, consistently inhibited growth of all Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus uberis strains, but none of the Escherichia coli strains. The present study, therefore, supports the protective effect of teat apex colonization by S. chromogenes by in vitro production of inhibitory substances.     

Experimental infection of the udder of ewes due to Mycoplasma bovis

Twelve freshly lactating ewes were experimentally infected with 2 Mycoplasma (M.) bovis strains via the teat canal in the left udder. The M. bovis infection produced a febrile clinical mastitis in all infected animals. M. bovis could be re-isolated regularly from the experimentally infected udder halves and the infection spread to the other halves. Some contact animals and 4 suckling lambs became naturally infected. Antibody titres were detected by means of the indirect hemagglutination test in blood sera 2 to 3 weeks post infectionem. The pathological lesions were similar to those of the M. bovis mastitis of cows. By the end of the trial the ewes had recovered from the clinical mastitis.     

荷斯坦奶牛隐性乳房炎与乳房性状的相关性分析

选择安徽淮南乳品公司为试验试点,随机抽取荷斯坦奶牛472头(1~≥6胎)进行隐性乳房炎与乳房性状相关性分析,测定的乳房性状主要包括前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置和乳头长度。结果表明:淮南地区荷斯坦奶牛隐性乳房炎的乳区阳性率和奶牛阳性率分别为25.79%和53.18%;乳房性状前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的线性评分分别为31.92分、47.02分、29.00分、37.64分、20.02分、39.74分、20.88分。隐性乳房炎的乳区阳性率与前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的表型相关系数分别是-0.0731、0.0211、0.1003、-0.0369、0.0996、-0.0323及-0.0151,其中与后房宽度、乳房深度为显著(P<0.05)的正相关,其余均未达到显著水平(P>0.05);奶牛阳性率与前房附着、后房高度、后房宽度、悬韧带、乳房深度、乳头位置、乳头长度的表型相关系数分别为-0.0427、0.0680、0.0347-、0.0060、0.1071、-0.0119和0.0223,除与乳房深度为显著(P<0.05)的正相关外其余均不显著(P>0.05)。     

Bovine serum albumin and cell counts in the diagnosis of subclinical udder infection

Summary

Puncture of the milk cisterns was performed in 120 bacteriologically positive quarters of forty‐seven lactating dairy cows on three farms. This method was used to determine whether the existing infection was an infection of the teat canal or one of the udder. The results were related to the concentration of bovine serum albumin (BSA) and the cell count in the milk. Of the bacteriologically negative quarters, both BSA levels (in 91 per cent of the quarters the BSA concentration was 0.20 mg. per ml. of milk or less) and cell counts (92 per cent contained less than 500,000 cells per ml. of milk) were low. In cases of udder infection with primary pathogenic bacteria there was a marked increase in cell count (90 per cent more than 500,000 cells per ml. of milk), whereas the increase in BSA was rather small (51 per cent still contained 0.20 mg. BSA per ml. of milk or less). While the difference in cell counts of milk from quarters with udder infections and teat canal infections with primary pathogenic bacteria was significant, the difference between the BSA levels of these two groups was not. Therefore, the cell count supplies more reliable information than does the BSA level of the milk. Of all infections, 23 per cent were found to be infections of the teat canal.     

Udder health in relation to udder and teat morphometry in Holstein Friesian × Sahiwal crossbred dairy cows

The present investigation involved 261 Holstein Friesian (HF) × Sahiwal cows to study the udder health as well as the udder and teat morphometry. The udder health was defined on the basis of bacteriology and California mastitis test of quarter foremilk. The morphometry parameters included udder fore depth (UFD, distance from the point where the fore udder merges within the abdomen to a point in front of the fore teats at the level of the udder base), udder rear depth (URD, distance from the bottom of the vulva to the base of the rear udder), udder depth (UD, level of the udder base with respect to hock joint), height of the udder from the floor, teat length, teat diameter (at mid of the teat barrel), teat-tip to floor distance and distance between the teats. The URD, UD and height of udder from the floor showed a significant (P?<?0.05) relation to the udder health with mastitic cows having larger URD, smaller udder distance from the floor and the udder base placed below the hock joint. The cows with teat length larger than 4.5 cm and teat diameter 3.0 cm or larger had significantly more quarters affected with mastitis. Further, cows with teats placed nearer to the floor were more susceptible to mastitis (P?<?0.01). No significant differences were found between healthy and mastitic udders with respect to UFD and distance between teats. It can be concluded that selection for optimum udder and teat morphometry in breeding programmes may help to reduce susceptibility to intramammary infections in HF × Sahiwal cows.     

Coagulase-negative staphylococci-emerging mastitis pathogens

Coagulase-negative staphylococci (CNS) have become the most common bovine mastitis isolate in many countries and could therefore be described as emerging mastitis pathogens. The prevalence of CNS mastitis is higher in primiparous cows than in older cows. CNS are not as pathogenic as the other principal mastitis pathogens and infection mostly remains subclinical. However, CNS can cause persistent infections, which result in increased milk somatic cell count (SCC) and decreased milk quality. CNS infection can damage udder tissue and lead to decreased milk production. Staphylococcus simulans and Staphylococcus chromogenes are currently the predominant CNS species in bovine mastitis. S. chromogenes is the major CNS species affecting nulliparous and primiparous cows whereas S. simulans has been isolated more frequently from older cows. Multiparous cows generally become infected with CNS during later lactation whereas primiparous cows develop infection before or shortly after calving. CNS mastitis is not a therapeutic problem as cure rates after antimicrobial treatment are usually high. Based on current knowledge, it is difficult to determine whether CNS species behave as contagious or environmental pathogens. Control measures against contagious mastitis pathogens, such as post-milking teat disinfection, reduce CNS infections in the herd. Phenotypic methods for identification of CNS are not sufficiently reliable, and molecular methods may soon replace them. Knowledge of the CNS species involved in bovine mastitis is limited. The dairy industry would benefit from more research on the epidemiology of CNS mastitis and more reliable methods for species identification.     

Risks factors associated with subclinical mastitis in water buffaloes in Pakistan

The present study was carried to ascertain the association of various risk factors of mastitis in water buffaloes. The milk samples from buffaloes were collected and screened through California Mastitis Test for the presence of mastitis. In the present study, 15.2 % prevalence of subclinical mastitis was recorded both at the government (13.4 %) and private farms (15.5 %). The chi-square analysis showed significantly higher involvement of the right rear and front quarters. The analysis of variance technique showed significant difference in live body weight, milk yield, teat end to floor distance (P?<?0.001), udder depth, teat length, and teat diameter in mastitic and healthy buffaloes. The frequency analysis also revealed significant difference between various groups including lactation stage, teat and/or udder pathology, teat shape, and udder shape (P?<?0.001). The logistic regression analysis revealed significant positive association of mastitis with milk leakage, live body weight, milk yield, parity, calf suckling, pendulous udder, number of attendants at the farm, dirty hind legs, and udder depth.     

Clinical and ultrasonographic findings in the mammary gland of sheep

AIM: To compare clinical and ultrasonographic findings and assess the value of ultrasonography for evaluating the structure and condition of the teat and teat canal of sheep. METHODS: The mammary glands of 30 lactating ewes were examined clinically and using ultrasonography. The distance from the teat tip to the ground was measured and diagnostic images of the body of the gland, gland cistern and teat cistern were obtained using an 8.5 MHz frequency ultrasonic transducer. A California mastitis test (CMT) and bacteriological culture were performed on milk samples collected from each half of each udder. RESULTS: Udder parenchyma and teats were palpably normal in 27/30 (90%) ewes. Milk clots or abnormalities were evident in 4/30 (13%) udders, lesions in the glandular parenchyma and/or teats were evident by palpation in 3/30 (10%), and pathogenic bacteria were cultured from 2/30 (7%). In both of the latter cases, mastitis was diagnosed based on clotted and discoloured appearance of milk and highly positive CMT reactions. Ultrasonographic examination in these udders revealed non-homogenous regions in the glandular tissue and alternating areas of hyperechogenic and hypoechogenic tissue. Overall, highly positive CMT reactions were evident in milk from 14/30 (47%) left halves and 9/30 (30%) right halves (p=0.02). No relationship between teat-to-ground distances and CMT results was evident (p>0.05). Teat canal lengths ranged from 5.7-10.3 mm (mean=8.6; SD=1.3 mm) and the widths from 1.8-3.1 mm (mean=2.3; SD=0.4 mm). Milk sampled from ewes that had long (> or = 9 mm) or wide (> or = 2 mm) teat canals was highly positive to the CMT in 75% and 83% of cases, respectively. CONCLUSIONS: Ultrasonographic measurements of the length and width of the teat canal appeared to correlate with CMT results. The use of ultrasonography in evaluating the health of the udder of small ruminants holds promise for the future.