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Costs of clinical mastitis and mastitis prevention in dairy herds.

A stratified random sample of 50 Ohio dairy herds, monitored for 1 year between March 1988 and May 1989, was used to estimate the component costs of clinical mastitis per cow-year overall and by organism, the component costs of an episode of clinical mastitis overall and by organism, and the incidence of clinical mastitis by organism. Each herd was visited monthly by a veterinarian who conducted on-farm interviews and completed standardized data-collection forms designed to elicit economic information about the on-farm costs of clinical mastitis and mastitis prevention. Producers collected milk samples prior to treatment of clinical mastitis cases. Culturing methods allowed identification of 18 specific mastitis pathogen classifications. Annual costs estimated were on a per cow-year and clinical episode basis. The monthly mean population of cows monitored was 4,068. Mastitis prevention cost $14.50/cow-year, whereas the cost incurred by producers because of clinical cases of mastitis was $37.91. Organisms prevalent in the cows' environment caused the most costly types of mastitis. Disregarding contaminated samples and episodes for which no milk samples were taken, mastitis for which 2 organisms were isolated accounted for 35.5% of costs of clinical mastitis, followed by cases for which Escherichia coli (21.3%) was isolated, cases for which culturing yielded no growth (8.6%), and cases for which esculin-positive Streptococcus spp (6.4%), Klebsiella spp (5.7%), esculin-negative CAMP-negative Streptococcus spp (5.1%), Enterobacter spp (4.8%), coagulase-negative Staphylococcus spp (4.1%), coagulase-positive Staphylococcus spp (3.0%), S agalactiae (2.5%), and Bacillus spp (1.2%) were isolated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Characteristics of dairy cows during episodes of bacteriologically negative clinical mastitis or mastitis caused by Corynebacterium spp.

OBJECTIVES: To use clinical and lactational characteristics to determine whether bacteriologically negative (BN) clinical mastitis episodes are more apt to be caused by gram-negative or gram-positive bacteria, and to investigate severity of clinical mastitis caused by Corynebacterium spp (COR). DESIGN: Case series. SAMPLE POPULATION: 300 clinical mastitis episodes affecting 123 dairy cows vaccinated against lipopolysaccharide core antigens. PROCEDURE: Cows were examined at onset of clinical mastitis, and 23 characteristics, including rectal temperature, heart rate, rumen contraction rate, degree of dehydration, udder and milk characteristics, lactation number, stage of lactation, and season of year, were recorded. Milk production and milk constituent concentrations before onset of mastitis were obtained from herd records. Values for cows with BN milk were compared with values for cows from which milk yielded gram-negative bacteria (GNB) or gram-positive cocci (GPC); logistic regression was used to predict which pathogen type was causing BN mastitis. Characteristics for cows from which milk yielded COR were compared with those of cows from which milk was BN or yielded GPC. RESULTS: BN clinical mastitis episodes differed significantly from episodes caused by GPC, and were similar to, but milder than, episodes caused by GNB. COR were isolated in a substantial proportion of mastitis episodes, but clinical signs were milder than when GPC were isolated. CLINICAL IMPLICATIONS: Most BN mastitis episodes in cows receiving lipopolysaccharide core antigen vaccines appear to be caused by low-grade infection with GNB, and treatment and management decisions should be made accordingly. The COR may be economically important clinical mastitis pathogens in some herds.

Animals↗

Genetic relationship between body condition score, dairy character, mastitis, and diseases other than mastitis in first-parity Danish Holstein cows.

The aim of this study was to explore the possibilities of using body condition score (BCS) or dairy character (DC) as indicators of mastitis and diseases other than mastitis in first-parity Danish Holsteins. The dataset included 28,948 observations on conformation scores and 365,136 disease observations. The analysis was performed using a multitrait linear sire model. Heritability estimates for BCS and DC were moderate (0.25 and 0.22), and heritability estimates for mastitis and diseases other than mastitis were low (0.038 and 0.022). Between BCS and diseases other than mastitis, the genetic correlation was -0.22, whereas the genetic correlation was -0.16 between BCS and mastitis. The genetic correlation between DC and diseases other than mastitis was 0.43, and between DC and mastitis it was 0.27. The genetic correlation between BCS and DC was -0.61. Residual correlations were close to 0, except between BCS and DC (-0.37). Including DC as an indicator of diseases other than mastitis will increase the accuracy of the predicted breeding value for diseases, especially when the progeny group is small. Using BCS as an additional indicator of diseases did not increase the accuracy. Breeding for less DC will increase resistance to diseases.

Animals↗

Clinical mastitis in two California dairy herds participating in contagious mastitis control programs.

The occurrence of clinical mastitis in two large California dairy herds over a 3-yr period is described. Herds had been participating for 15 or 22 yr in mastitis control programs against Streptococcus agalactiae and Staphylococcus aureus, had low bulk tank SCC, and had maintained good standards of hygiene and husbandry, but clinical mastitis remained a serious problem. A total of 1654 clinical mastitis cases were detected; the annual incidence in each herd was 49%. Coliform bacteria and environmental streptococci were etiological agents in 60% of the total clinical mastitis cases; coliforms produced 1.6 times more clinical mastitis than environmental streptococci. A higher susceptibility to clinical mastitis, primarily from coliform bacteria and environmental streptococci, was found in the first months of lactation. Clinical mastitis incidence peaked for cows in lactations 4 and 5 and was lowest during the first lactation. Highest incidence of clinical mastitis due to coliform bacteria and environmental streptococci at each dairy occurred during the rainy season (late fall and winter).

Animals↗

Conversion of chronic staphylococcal mastitis to acute gangrenous mastitis after neutropenia in blood and bone marrow produced by an equine anti-bovine leukocyte serum.

A stock strain of Staphylococcus aureus of mastitis origin, characterized by alpha-, beta-, and delta-toxins, was used to produce chronic mastitis of 20 to 300 days' duration in 6 lactating mammary quarters of 4 cows. Early acute Streptococcus agalactiae mastitis was produced in 1 additional mammary quarter of 1 cow. Equine anti-bovine leukocyte serum (EABLS) was administered to all cows by continuous intravascular drip for 12 to 32 hours. Neutropenia in blood and partial depletion of neutrophil reserve in bone marrow were produced. Chronic subclinical staphylococcal mastitis in 2 quarters of 1 cow changed to gangrenous mastitis by the 40th hour after EABLS administration and led to death of the cow. The disappearance of neutrophil leukocytes from the milk was followed by uninhibited multiplication of S aureus. Probably, staphylococcal leukocidins accelerated the destruction of neutrophils in the milk as S aureus multiplication became intensified. In another quarter of the same cow that was infected with Str agalactiae, neutrophil leukocytes were present in milk as long as 3 days after their disappearance from blood and bone marrow. This may give some indication of the extravascular life-span of the neutrophil in the udder in mastitis. The 2nd cow died at the 16th hour from the start of EABLS administration and at a time when gangrenous mastitis was in the initial stages of development. The S aureus-infected quarters of the 2 remaining cows did not become gangrenous. Administration of EABLS to these 2 cows did not significantly reduce the numbers of neutrophil leukocytes entering the milk of the 3 S aureus-infected quarters. It is concluded that continuous diapedesis of neutrophil leukocytes into the milk in chronic staphylococcal mastitis protects the gland against the development of gangrenous mastitis in the presence of a strain of S aureus capable of alpha-toxin production.

Agranulocytosis↗

Flotation of mastitis pathogens with cream from subclinically infected quarters. Prospects for developing a cream-rising test for detecting mastitis caused by major mastitis pathogens.

Bacterial isolates, originating from 36 subclinically infected quarter milk samples, were labelled with 75Se and checked for cream-rising at various temperatures in a system analogous to the ABR test ("Abortus Bang Ringprobe"; the cream-rising test based on stained brucella organisms for detection of brucellosis). Diagnostic specificity and sensitivity were analyzed in experiments where labelled bacterial isolates were mixed with a number of quarter milk samples with known bacteriological status as well as samples from healthy control quarters. Creaming at 37 degrees C resulted in specific "recognization" as the bacterial isolates showed preferential flotation in the milk samples from which they had been isolated as well as is milk samples harbouring the same bacterial species. At lower creaming temperatures, the specificity was lost since all the isolates became concentrated in the cream phase irrespective of the milk sample. When comparing the specific recognization by cream of the respective bacteria, bacterial species vary: The prospects for developing diagnostic cream-rising tests for Streptococcus agalactiae, Staphylococcus aureus and Escherichia coli seems promising, but less so for coagulase-negative staphylococci, Streptococcus dysgalactiae, and Streptococcus uberis. The mechanism behind the cream-rising of labelled bacteria at 37 degrees C seems to lie in specific fat globule membrane-bound immunity of IgA type. Therefore the milk fat globules from chronically infected quarters function as absorbents for the respective isolates. Flotation of bacteria with cream indicates an in vivo mechanism enabling bacteria to invade the upper parts of milk ducts within the udder.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Experimental mastitis in mice induced by coagulase-negative staphylococci isolated from cases of mastitis in nursing women.

Coagulase-negative staphylococci are frequently isolated from the milk of women with signs of puerperal mastitis. In order to evaluate the pathogenicity of these bacteria, strains of S. epidermidis and S. saprophyticus isolated from cases of mastitis in nursing women were inoculated into the mammary glands of lactating mice. Although clinical signs of mastitis were absent, by histological examination, mastitis was demonstrated in 78-93% of the glands. Abscesses were found in a few cases only. The inoculated bacteria were re-isolated in 41-61% of the cases, and when inoculated in numbers of 10(2) to 10(4) c.f.u. the bacteria multiplied above input levels in several cases. It is concluded that coagulase-negative staphylococci isolated from the milk of women with puerperal mastitis can produce mastitis in mice and should be considered as a possible etiologic agent of mastitis in nursing women.

Animals↗

The New South Wales mastitis control program. 1. Field aspects and their effect on clinical and subclinical mastitis.

A mastitis control program based on teat dipping and dry cow therapy was evaluated in 35 herds over a 3 year period. The incidence of subclinical mastitis as detected by the Rapid Mastitis Test (RMT) fell from 34% to 12% quarters positive, a reduction of 65%. Clinical mastitis was reduced from 37 clinical cases per 100 cows in the first 3 month period to 12 clinical cases per 100 cows in the last 3 month period, a reduction of 68%. Variations in response to the program in the reduction of subclinical and clinical mastitis are discussed and the results compared with similar trials conducted overseas. The Modified Whiteside Test was used on bulk milk samples from the control herds and these results were significantly correlated with the prevalence of subclinical mastitis assessed by RMT individual quarters.

Animals↗

Chronic granulomatous mastitis: review of 26 cases with special reference to chronic lobular mastitis.

Twenty six cases of chronic granulomatous mastitis are reported in a 5 year period and the slides are reviewed. They are sub-classified into Chronic lobular mastitis (CLM), Plasma cell mastitis and subareolar granuloma. There are 10 cases each of CLM and plasma cell mastitis and one of subareolar granuloma. All the three conditions are associated with duct ectasia. Fat necrosis and infective granulomas were 2 each and one of foreign body granuloma. These lesions can be easily differentiated by histology. While most of the CLM occurred in younger age group, plasma cell mastitis is seen in older women. Histologically, there is a florid inflammatory cell reaction of the stroma with dilatation and destruction of some ducts, with microabscess formation. In plasma cell mastitis, the lesion is more chronic with predominance of plasma cells and involutionary changes of the ducts are seen.

Adult↗

Therapy of bovine mastitis: the intramammary tissue compatibility of mastitis remedies administered intracisternally to cows.

Eight different mastitis remedies were administered intracisternally on a rotational basis to the 48 quarters of 12 mastitis negative cows. The resulting intramammary reactions were monitored by determining the Somatic Cell Count (SCC) and Bovine Serum Albumin (BSA) levels in milk. The reactions observed indicate that the intramammary cellular reactions frequently elicited by the local treatments in the treated and sometimes even in the untreated quarters of the treated udders are not necessarily inflammatory in nature. Evaluation of the intramammary tissue compatibility of a mastitis remedy mainly in terms of SCC values therefore seems unreliable. Moreover, it may do injustice to a product unless the SCC values are augmented by BSA or other determinations providing a more accurate indication of truly mastitic reactions. The investigation also implies that the patterns of cellular reactions related to individual mastitis remedies require further elucidation before they can be used as indications of an advantageous or disadvantageous intramammary tissue compatibility of a product. Intramammary tissue compatibility, as such, of mastitis remedies and comparable agents requires definition. It seems more expedient, however, that such a definition and the necessary standardization of mastitis remedies in terms of their intramammary tissue compatibility be attempted by the International Dairy Federation (IDF).

Animals↗

Patterns of intramammary infection and clinical mastitis over a 5 year period in a closely monitored herd applying mastitis control measures.

The udder health of a research herd of between 160 and 220 Friesian cows run on a commercial basis has been monitored closely, including detailed bacteriological study, over 5 years. The five point mastitis control plan had been in use for several years prior to this study and was continued with minor alterations to the management of the plan, more detailed bacteriological monitoring and increased encouragement to apply it. It has proved possible to make a substantial improvement in the udder health of the herd. The percentage of infected cows fell from 21.9 to 12.0 and the percentage of infected quarters from 7.3 to 3.3. The main benefit has been a drastic reduction in the rate of clinical and subclinical mastitis caused by coagulase-positive staphylococci. However the total incidence of clinical mastitis did not change substantially, averaging around 30 cases/100 cows per year. This was largely because environmental mastitis organisms were responsible for 65% of all clinical cases. The results showed marked differences in the patterns of infection due to the environmental mastitis pathogens, Gram-negative bacteria and aesculin-hydrolysing streptococci, suggesting different mechanisms of invasion of the gland.

Animals↗

Impact of mastitis control measures on milk production and mastitis indicators in smallholder dairy farms in Kiambu district, Kenya.

Bovine mastitis and mastitis control were investigated on smallholder farms in central Kenya. After an initial observational study, a clinical trial to assess the impact of three different mastitis control strategies--(1) improved udder hygiene, (2) treatment of subclinical cases, and (3) a combination of these--was conducted on 100 randomly selected farms with 332 lactating cows. Before the implementation of control measures, the milk yield was low (mean 6.5 kg/day; median 6 kg/day) and somatic cell counts (SCC) were high, with 80% and 43% of cows having milk with SCC greater than 250 x 10(3) cells/ml and 600 x 10(3) cells/ml, respectively. Infectious pathogens were also commonly isolated, with 63% of cows being positive for pathogenic bacteria. Neither intervention strategy alone had any effect on mastitis indicators or milk yield. In combination, the measures had some impact, lowering the prevalence of contagious pathogens by 18%, but this was not reflected in a significantly increased milk yield, lowered SCC or reduced incidence of clinical mastitis.

Animal Husbandry↗

Production effects related to mastitis and mastitis economics in dairy cattle herds.

Mastitis is the most prevalent production disease in dairy herds world-wide and is responsible for several production effects. Milk yield and composition can be affected by a more or less severe short-term depression and, in case of no cure, by a long-acting effect, and, sometimes, an overlapping effect to the next lactation. Summary values in the literature for losses of milk production were proposed at 375 kg for a clinical case (5% at the lactation level) and at 0.5 kg per 2-fold increase of crude SCC of a cow. Due to the withdrawal period after treatment, composition changes in milk can almost be neglected in economic calculations. Lethality rate for clinical mastitis is very low on the average, while anticipated culling occurs more frequently after clinical and subclinical mastitis (relative risk between 1.5 and 5.0). The economics of mastitis needs to be addressed at the farm level and, per se, depends on local and regional epidemiological, managerial and economic conditions. To assess the direct economic impact of mastitis, costs (i.e. extra resource use) and losses (i.e. reduced revenues) have to be aggregated. To support decision making for udder health control, it is necessary to use a marginal approach, based on the comparison of the losses avoided and the additional costs of modified plans, compared to the existing ones.

Animals↗

Genetic improvement of mastitis resistance: validation of somatic cell score and clinical mastitis as selection criteria.

Mean daughter deviations for clinical mastitis among second-crop daughters were regressed on predicted transmitting abilities for clinical mastitis and lactation mean somatic cell score in first-crop daughters to validate the predictive ability of these traits as selection criteria for reduced incidence of clinical mastitis. A total of 321 sires had 684,897 second-crop daughters, while predicted transmitting abilities were calculated for 2159 sires, based on 495,681 records of first-crop daughters. Predictive ability, as a measure of efficiency of selection, was 23 to 43% higher for clinical mastitis than for lactation mean somatic cell score. Compared to single-trait selection, predictive ability improved 8 to 13% from utilizing information on both traits. The relative weight that should be assigned to standardized predicted transmitting abilities from univariate genetic analyses were 60 to 67% for clinical mastitis and 33 to 40% for lactation mean somatic cell score. No significant nonlinear genetic relationship between the two traits was found.

Analysis of Variance↗

Prevalence of mastitis pathogens in herds participating in a mastitis control program.

Bacteriological data from herd surveys by the Massachusetts Mastitis Laboratory were analyzed. Comparisons of percent cows and quarters with major mastitis pathogens and types of bacteria isolated were between Streptococcus agalactiae-positive (1105 cows from 17 herds) and Streptococcus agalactiae-negative herds (1088 cows from 17 herds). Major mastitis pathogens were isolated from 58.5% of cows and 37.0% quarters in Streptococcus agalactiae-positive herds. The most frequently isolated bacteria were Streptococcus agalactiae and Staphylococcus aureus, and together these accounted for 87% of organisms isolated. In contrast, major mastitis pathogens were isolated from only 26.3% of cows and 10.2% of quarters in Streptococcus agalactiae negative herds. Streptococci other than Streptococcus agalactiae, Staphylococcus aureus, and coliforms were the predominant organisms isolated. Seventeen additional Streptococcus agalactiae negative herds were surveyed annually over 6 yr. An average of 25.8% of cows and 10.3% of quarters were positive for major mastitis pathogens during this time. The predominant bacteria isolated were streptococci other than Streptococcus agalactiae, Staphylococcus aureus, and coliforms. There was little variation between years.

Animals↗

[Methods of diagnosing subclinical mastitis in dairy cow mastitis control programs].

The number of somatic cells and the isolation of the causative agents of mastitis in quarter, composite, bucket, and bulk tank samples of cow's milk was determined four times during a six-month period. The number of somatic cells in milk samples indicated a degree of mastitis infection and was influenced neither by the year season nor by the length of lactation. At a repeated examination of 28 dairy cows an increased number of somatic cells in milk was found once in 68 udder quarters and with three successive samplings only in 21 quarters. The etiological agents of mastitis were detected once in 31 quarters and three times in succession only in five quarters. The number of cows positive by the number of cells in quarter samples of milk increased from 52.9-58.8% at a single examination to as much as 100% at four examinations. The etiological agents of mastitis were isolated in a single examination in 17.6% of cows and at four examinations in 58.8% of cows. The composite and bucket samples of milk containing 200 to 300 thousand cells per ml are recommended to be considered as mastitis-positive: in 68 to 78% they came from cows having more than 500 thousand cells per ml at least in one quarter sample. The number of cells in a bulk sample was in correlation with the percentage of cows having a positive NK-test (similar to CMT) and positive isolation of S. agalactiae from quarter milk samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Herd incidence of bovine mastitis in four Danish dairy. districts II. Evaluation of the effect of the mastitis control scheme.

Bacteriological and cytological examinations have been carried out on samples from 6,808 cows belonging to 339 herds in four Danish dairy districts. After a discussion of differences between the districts as regards intensivity of mastitis control, public health surveillance, etc., definitions are given of certain terms, such as presence of bacteria, infection, pathogenic versus non-pathogenic (less pathogenic) organisms. The rate of infection with pathogenic organisms varies between districts from 23% to32% on a cow basis, and from 8% to 12% on a quarter basis. A comparison, on a cow basis, of the occurrence of pathogens as recorded in 1955/58 in three Danish surveys comprising 11 dairy districts, with the occurrence as recorded in four districts in 1972, showed a decline in incidence of between 7 and 9 percentage units. Together with the decline in incidence a definite change in the composition of the udder flora has taken place during that period. In particular, there was a pronounced fall in the occurrence of Group B, C, G, and L streptococci, and a relative increase in the occurrence of Staphylococcus aureus. A comparison, on a quarter basis, with the occurrence of pathogens in 30 English herds subjected through three years to intensive mastitis control, including systematic treatment of dry cows, teat dipping, and weekly inspection, showed that by such a programme a slightly lower level of infection was reached than in the 399 Danish herds which had been subjected to collective control for 10-15 years. The annual financial loss per cow suffering from mastitis being estimated at D.kr. 600.-, the reduction noted in the occurrence of bacteria in cows' udders implies an annual national saving of D.kr. 42 million on account of the Danish mastitis control. The total annual expenditure on Danish mastitis control is estimated at D.kr. 9million expenses would rise to some 70 million D.kr. if all registered cows were to be treated on drying-off, and if general teat dipping was to be carried out.

Animals↗

Prevalence of contagious pathogens of bovine mastitis and use of mastitis control practices.

A cross-sectional study of 1,032 dairy herds in Ohio was conducted to determine the prevalence of the major contagious pathogens of mastitis (Streptococcus agalactiae and Staphylococcus aureus) and the use of common mastitis control measures. Herd owners were surveyed by mail concerning their use of mastitis control measures. The survey focused on treatment of nonlactating cows, postmilking teat dipping, culling practices, milking machine maintenance, treatment for clinical mastitis, and premilking hygiene practices. Nearly 90% of questionnaires were returned. The prevalence of Streptococcus agalactiae and Staphylococcus aureus was determined by use of bulk-tank milk samples. Most herds (n = 802) met the criteria for classification into 1 of 4 groups: (1) Free of contagious pathogens, as determined by inability to isolate coagulase positive staphylococci (CPS) and esculin-negative CAMP positive streptococci (ENCPS) from 3 bulk-tank milk samples, (2) CPS, but not ENCPS, isolated from at least 1 sample, (3) ENCPS, but not CPS, isolated from at least 1 sample, (4) both ENCPS and CPS isolated from at least 1 sample. The number of herds in which both ENCPS and CPS were isolated was low; therefore, these herds were grouped with herds in which ENCPS alone was isolated for the evaluation of mastitis control practices related to herd pathogen status. Herd somatic cell count (SCC) was determined using Dairy Herd Improvement Association data by calculating the geometric mean SCC from individual cow test day SCC. Twelve months of SCC data from 741 herds were included in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗