Estimation of milk production losses due to sub-clinical mastitis in dairy cattle in Costa Rica

Five dairy farms, situated on the slopes of the volcano Poás in the pre-mountain cloud forest ecological zone, Alajuela and Heredia Provinces, Costa Rica, provided data for estimation of the production losses due to sub-clinical mastitis. Within the same farm, cows with proven sub-clinical mastitis were matched with cows without signs of sub-clinical mastitis, according to breed, lactation number and days in lactation. A total of 529 cows were detected with sub-clinical mastitis, of which only 200 could be paired with control cows free of mastitis; each pair was used only once.

Crude milk production losses per cow with sub-clinical mastitis were estimated at 1.56 kg day⁻¹for daily milk yield. Milk production loss per affected quarter due to sub-clinical mastitis was estimated to be 17.6% on average. The decrease in milk production in heifers with sub-clinical mastitis did not differ significantly from the decrease in production in older cows. No significant difference in milk production loss was detected when the data were stratified on parity or the number of quarters affected.     

Costs associated with selected preventive practices and with episodes of clinical mastitis in nine herds with low somatic cell counts

Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Economic aspects of mastitis: new developments

Good udder health is not only important for the dairy farmer but, because of increasing interest of consumers in the way dairy products are produced, also for the dairy production chain as a whole. An important role of veterinarians is in advising on production diseases such as mastitis. A large part of this advice is given around the planning of management to maintain or improve the udder health status of a farm. Mastitis is a costly disease, due to losses (a reduction of output due to mastitis) and expenditure (additional inputs to reduce the level of mastitis). Worldwide, published estimates of the economic losses of clinical mastitis range from ?1 to ?7 per cow on a farm, with large differences between farms, e.g. in The Netherlands, losses due to clinical and subclinical mastitis varied between ?7 and ?98 per cow per year. Moreover, farmers tended to underestimate these costs. This indicates that for a large proportion of farms there are many avoidable losses. In order to provide good support to farmers' decision-making, it is important to describe the mastitis setting not only in terms of disease, e.g. incidence of clinical mastitis, but also in monetary terms; and to make good decisions, it is necessary to provide the dairy farmer with information on the additional expenditure and reduced losses associated with alternative decisions. Six out of 18 preventive measures were shown to have a positive nett benefit, viz blanket use of dry-cow therapy, keeping cows standing after milking, back-flushing of the milk cluster after milking a cow with clinical mastitis, application of a treatment protocol, washing dirty udders, and the use of milkers' gloves. For those measures that included a large amount of routine labour or investment, the reduced losses did not outweigh the additional expenditure. The advisor cannot expect that measures that are cost-effective are always implemented. Reasons for this are the objectives of the dairy farmer can be other than maximisation of profit, resources to improve the mastitis situation compete with other fields of management, risk involved with the decision, economic behaviour of the dairy farmer, and valuation of the cost factors by the dairy farmer. For all decision-makers this means that, although financial incentives do have an effect on the management of mastitis, it is not always sufficient to show the economic benefits of improved management to induce an improvement of management of mastitis.     

Cost estimation of heifer mastitis in early lactation by stochastic modelling

Heifer mastitis, reflected by an elevated somatic cell count (SCC) in early lactation (SCCel), results in a decreased milk production, a higher risk for subclinical and clinical mastitis during lactation, and an elevated culling hazard. The aims of this study were to calculate the costs of heifer mastitis defined as an elevated SCC in early lactation, and to show the variation of these costs in the Dutch/Belgian dairy sector. A stochastic model, in which the variation and uncertainty of heifer mastitis are taken into the account, was developed with input data from literature and expertise. Costs were estimated, using default values. The mean costs for an elevated SCCel that cured were on average euro 13/heifer present on a farm (range: euro 0-118), for an elevated SCC at calving proceeding in subclinical mastitis on average euro 5/heifer present on a farm (range: euro 0-euro 82), and for a clinical heifer mastitis case associated with an elevated SCC after calving on average euro 270. On average this results in euro 13/heifer present on a farm (range: euro 0-137). Combined, these three cost aspects result in a total cost of on average euro 31/heifer present on a farm (range: euro 0-220). The large variation in the costs is very important regarding farm management and farm support. The difference in costs reflects also the difference in room for investment. When the costs that can be prevented are estimated at farm level, these data can be of help in setting goals in herd health advice and farm management.     

Loss in milk yield and related composition changes resulting from clinical mastitis in dairy cows

Relationships between clinical mastitis and milk yield and composition in dairy cows were reviewed. Requirements for inclusion were: data had to be collected after 1975; dependent variables for milk yield and milk composition had to be defined at the cow level; mastitis cases had to be defined by clinical signs, and at least 250 lactations had to be considered. Twenty studies dealing with milk-yield loss and, for four of them, also with related composition changes were selected. Study populations, design of data collection, and analysis methods differed widely between studies. As expected from these differences – but also due to structural-variation factors such as type of pathogen, animal and production level – estimates for milk-yield losses differed in average magnitude and pattern. Literature data regarding changes in milk-fat % and total-protein % changes were contradictory. Critiques of materials and methods allowed us to propose some final recommendations for values to be used as basic inputs in economic calculations of losses caused by mastitis.     

The economic benefit of treating subclinical Streptococcus agalactiae mastitis in lactating cows

The economic benefits of treating lactating cows for Streptococcus agalactiae mastitis were studied at a large (689 milking cows) central California dairy. Postcure milk production of case cows (infected, treated, and cured) was compared with production of paired control cows (uninfected) and was matched for yield, days in milk, days in gestation, and parity. A simulation was used to plot expected lactation curves for mastitic cows (infected, not treated) with characteristics similar to those of each control cow, and these curves were compared with actual case-cow lactation curves. The difference in actual and expected production was used to calculate net economic benefits of treatment. Comparison of expected with actual production indicated a net benefit from treatment of $396/cow for cows treated in early lactation and $237 for cows treated in midlactation, but a net loss of $55 for cows treated in late lactation. Lactation number did not have a significant impact on economic benefits of treatment. In contrast to other studies indicating no economic benefit from treating mastitis during lactation, this study's positive results may have been attributable to the high cure rate (98%) and the subclinical form of mastitis being treated. Streptococcus agalactiae mastitis treatment during early and midlactation would appear to be an economically justifiable option for dairy managers.     

Milk yield and associated economic losses in quarters with subclinical mastitis due to <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> in Ethiopian crossbred dairy cows

The objective of the study was to estimate the prevalence and losses associated with subclinical mastitis (SCM) caused by Staphylococcus aureus in Ethiopian crossbred dairy cows. A split-udder trial was carried out to determine milk yield losses in udder quarter with S. aureus-caused SCM. Each quarter of the study cows was examined using the California Mastitis Test (CMT) and quarter milk production was measured over a period of 8 days. Milk yield losses for CMT positive quarters were estimated by comparing production of quarters with CMT score 0. Mean milk yield for uninfected healthy quarters was 1.66 kg per milking (95% CI, 1.66–1.55 kg per milking), and the rate of milk reduction for quarters with CMT scores of 1+, 2+, and 3+ was 25%, 33%, and 48%, respectively. Economic losses at different farm-size levels were calculated by multiplying the prevalence of CMT scores with milk yield losses associated with respective CMT scores. In Debre Ziet dairy herds, a quarter with SCM due to S. aureus lost an average of 34.5% of its potential milk production while the total milk yield loss per cow was estimated at 6.8%. Losses were highest in large-scale (13%) farms and lowest (3.7%) in small-scale. Based on the prevalence, the overall financial loss for each cow per lactation was 984.64 Eth Birr (US78.65) and losses in large farms (1,882.40 Eth Birr or US78.65) and losses in large farms (1,882.40 Eth Birr or US150.35) were over 3.5 times the loss in small-size farms. These figures possibly underestimate the potential benefits of mastitis control program as they do not include other direct and indirect costs.     

Management of dairy heifers and its relationships with the incidence of clinical mastitis

AIM: To describe aspects of management of dairy heifers before calving and determine risk factors for clinical mastitis postpartum in heifers, at the herd level, under pasture-based management systems in the Waikato and Taranaki regions of New Zealand. METHODS: Dairy herdowners (n=578) provided information via a prospective survey about their practices for rearing heifers and management of mastitis. A proportion of herdowners (n=250) subsequently provided data on the cases of clinical mastitis in their herds, including the date, cow identification, age and quarter affected from cases occurring in the 4 months after the planned start of calving (PSC) in the subsequent lactation. The relationship between management factors and the proportion of heifers diagnosed with clinical mastitis within a herd was examined using bivariate and multivariate analyses. RESULTS: The herd average percentage of heifers with clinical mastitis was 13.6 (95% confidence interval (CI)=12.3-14.9)%, and multiparous cows with clinical mastitis was 9.0 (95% CI=8.2-9.8)% in the first 4 months of lactation. There were positive relationships between the proportion of heifers with clinical mastitis and average milk production per cow (kg milksolids/ lactation; p<0.001), number of cows milked per labour unit (p=0.003), stocking rate (<> 3.30 cows/ha; p=0.002), and incidence of clinical mastitis in multiparous cows (%/120 days; p<0.04), in the final multivariate model. The proportion of heifers with clinical mastitis per herd was lower in herds that milked their lactating cows in multiple groups (p=0.02). CONCLUSIONS: The risk of clinical mastitis in heifers was significantly associated with management practices. It may be possible to reduce the incidence of clinical mastitis in heifers by modification of management practices at the herd level, and further studies are required to investigate this.     

Milk losses associated with somatic cell counts per breed, parity and stage of lactation in Canadian dairy cattle

The reduction in milk production caused by subclinical mastitis in dairy cattle was assessed through the regression of test day milk yield on log-transformed somatic cell counts (LnSCC). Data was obtained from Valacta, Quebec, and a total of 312,756 test day records from Ayrshire cows and 1,869,785 test day records from Holstein cows were included in the analyses. A segmented regression was fitted to estimate the cutoff point in the LnSCC scale where milk yield starts to be affected by mastitis. The statistical model used to explain daily milk yield included the effects of herd–year-season of test (random), days in milk, age at calving and LnSCC, and analyses were performed by breed, parity and stage of lactation. The cutoff point where milk yield starts to be affected by changes in LnSCC was estimated from data to be around 2 (approximately 7400 cells/mL) for Canadian Ayrshires and Holsteins. Milk losses per unit increase in LnSCC varied from 0.55 to 0.84 kg/day in first lactation Ayrshires, from 0.33 to 0.55 kg/day in first lactation Holsteins, from 0.74 to 2.45 kg/day in adult Ayrshires and from 0.77 to 1.78 kg/day in adult Holsteins. Daily milk losses caused by changes in LnSCC were dependent on breed, parity and stage of lactation, and these factors should be considered when estimating losses associated with subclinical mastitis.     

The cost of summer mastitis.

The incidence of summer mastitis on 95 dairy farms in southern England was monitored in the summer of 1987. Data on the type of animal infected, the fate of the animals immediately and over the succeeding lactation, and the procedures used in treating the infections were collected for 144 cases. Twenty-five per cent of cases were attended by veterinary surgeons. Most of the animals received parenteral antibiotics and on average each received five tubes of intramammary antibiotic. The incidence of infection was highest in pregnant and calving heifers, more than 2 per cent of the animals at risk, and lowest (0.04 per cent) in calves, although more than twice as many dry cows were infected. Over half of the farms reported summer mastitis, with 36 per cent suffering more than one case. The greatest economic loss, 49 per cent of the total, was from lost milk production; and 37 per cent was from lost animal value, cull and calf losses. The average loss was 192 pounds per case. Using national incidence data from England and Wales, the cost to the UK dairy industry in 1987 was 6.22 million pounds.     

Reduced Milk Production in Udder Quarters with Subclinical Mastitis and Associated Economic Losses in Crossbred Dairy Cows in Ethiopia

The objective of the study was to estimate the losses associated with subclinical mastitis (SCM) in crossbred dairy cows in the Central Highlands of Ethiopia. A split udder investigation was performed with 30 cows to determine production losses associated with SCM. Each quarter of the study cows was examined using the California Mastitis Test (CMT) and quarter milk production was measured over a period of 8 days. Production losses were determined for different CMT scores by comparing production of quarters with CMT score 0 to quarters with CMT scores trace, 1, 2 and 3, respectively. Using data from a recently published study, economic losses were determined for different farm sizes and production subsystems by multiplying the prevalence of the respective CMT scores with the production losses associated with these CMT scores. Mean quarter milk production was 0.82 + 0.40 kg per milking in the split udder trial. Milk production was reduced by 1.2%, 6.3%, and 33% in quarters with CMT scores 1+, 2+, and 3+, respectively. Using data from the published study, a quarter with SCM lost an average of 17.2% of its milk production. Production losses associated with SCM were estimated at 5.6% for the Addis Ababa Milk Shed. Stratified losses were highest (9.3%) in urban dairy farms (UDF) and small-scale farms (6.3%). The estimates of the financial losses ranged from US$29.1 in dairy herds in secondary towns (DHIST) to US$66.6 in UDF. A total loss of US$38 was estimated for each cow per lactation. Reducing mastitis in UDF (highest prevalence) to the level of DHIST (lowest prevalence) could reduce the loss by US$35. As this does not include costs associated with treatment or culling of diseased cows, this figure probably underestimates the possible benefits of control measures.     

Incidence and economics of clinical mastitis in five Holstein herds in the Czech Republic

Data on clinical mastitis (CM) collected between 1996 and 2003 on five Holstein dairy farms in the Czech Republic were analyzed. Lactational incidences of CM, averaged across farms and calculated only from cows with complete lactations, were 0.35, 0.45 and 0.57 for the first, second and third plus subsequent lactations, respectively. The mean numbers of CM cases per cow and lactation were 0.63, 0.94 and 1.22, and the incidence of CM cases per cow-year at risk were 0.68, 1.00 and 1.27 for the first, second and third plus subsequent lactations, respectively. Longitudinal analysis of CM prevalence based on daily records showed the highest proportion of infected cows in the first 10 days of lactation. The within-farm incidence of CM cases per cow per year, averaged over lactations, ranged from 0.53 to 1.56 with a mean value of 0.94 in the whole data set. Direct financial losses from CM per cow per year within farm ranged from 43.63 to 84.84 euros. They included losses from discarded milk, cost for drugs, veterinary service, herdsman's time, cost for an extra milking machine and cost for antibiotic drying of cows. The economic value of CM incidence (change in direct losses per cow per year when increasing CM incidence by one case above the average value) ranged from 58.3 to 80.1 euros per CM case per cow per year with the mean value of 62.6 euros per CM case per cow per year in the total data set. Daily prevalence rate of CM was shown to be the best among various indicators of CM susceptibility, because it accounted for the censored character of the data and for repeated cases of CM within lactations. In order to reduce the incidence of clinical mastitis for dairy cattle in the Czech Republic, we recommend that it should be included as a goal in the breeding program.     

Effects of clinical mastitis on reproductive and milk performance of Holstein cows in Morocco

The aim of this study was to determine the influence of clinical mastitis and time of first mastitis occurrence on reproductive and milk performance of Holstein cows. Data were collected in a dairy farm from 2008 to 2012 on 1725 cows, among which 464 cows with mastitis. To determine the influence of clinical mastitis on reproductive and milk performance, models included fixed effects of parity, calving season, calving year, and group (cows with and with no mastitis). To determine the effect of time of 1st mastitis occurrence on reproductive performance, the mastitic cows group was further reclassified into three groups: prior to 60 days, between 60 and 90 days and greater than 90 days postpartum. For milk performance, the mastitic cows group was divided into two groups: before and after peak milk yield. Clinical mastitis had significant effects on calving to first AI interval, milk yield, and fat yield, but a non-significant effect on days open, number of inseminations per conception, and milk fat percentage. Mastitic cows had a calving to first AI interval 6.1 days longer and 549.6 kg milk and 20.4 kg fat per 305 days of lactation lower than those with no mastitis. Time of 1st mastitis occurrence did not have any significant effect on reproductive performance. Further, milk and fat yields of cows diseased before peak milk yield were 506 kg and 23.9 kg, respectively, lower than those of cows affected after peak milk yield. Extra attention needs to be paid to mastitis during the early postpartum period.

     

乳酸菌防治奶牛乳房炎的作用效果及前景展望

乳房炎是奶牛常见的疾病之一,患病奶牛因其废弃奶的产生,以及治疗和淘汰等相关费用的增加,给奶牛养殖业带来了巨大的经济损失.目前,对于奶牛临床性乳房炎的治疗主要依赖于抗生素,而抗生素的长期大量使用会导致耐药性病原菌的产生和牛奶中的药物残留等问题.作为抗生素的潜在替代品,乳酸菌在防治病原微生物方面很有潜力,现综述了乳酸菌防治...     

Intramammary treatment of clinical mastitis of dairy cows with a combination of lincomycin and neomycin, or penicillin and dihydrostreptomycin

AIM: To compare clinical and bacteriological cure rates of clinical mastitis following treatment with intramammary preparations containing either lincomycin and neomycin or penicillin and dihydrostreptomycin. METHODS: Cases of clinical mastitis were sourced from four seasonal-calving dairy herds in the central Waikato region of New Zealand during the first 120 days of lactation. Affected quarters were infused three times at 12 h intervals with either 333 mg lincomycin plus 100 mg neomycin (lin/neo; 197 glands),or 1,000 mg penicillin plus 500 mg dihydrostreptomycin (pen/DHS; 207 glands). Milk samples were collected for bacteriology from each quarter immediately before and approximately 21 days after initiation of treatment. Additionally, a composite milk sample from each cow was collected, on average, 54 days after enrolment for assessment of milk yield, composition and somatic cell count (SCC). The probability of bacterial cure was initially analysed using Chi-squared analysis, and factors that were associated (p<0.2) were offered to a reverse stepwise logistic regression model. Continuous variables (e.g. milk solids production and log10 SCC) were analysed using general linear models. RESULTS: A total of 404 quarters diagnosed with clinical mastitis, from 282 cows in the first 120 days of lactation, were included. Streptococcus uberis, coagulase-negative staphylococci and Staphylococcus aureus were isolated from 56.5%, 18.8% and 10.0% of the bacteriologically positive quarters. There was no difference in the bacteriological cure rate (76.7% vs 76.7%, OR=0.94; p>0.8), the log10 SCC (2.1, SE 0.1, vs 2.0, SE 0.1; p>0.3) or milk production (1.2, SE 0.1, vs 1.2, SE 0.1, kg milksolids/cow/day; p>0.7) between lin/neo vs pen/DHS treatments, respectively. However, the proportion of cows re-treated following initial treatment was higher for the lin/neo compared to pen/DHS-treated group (16.3% vs 5.2%, OR=3.46; p<0.05). CONCLUSIONS: No difference in bacteriological cure rate, milk production or SCC was evident between lin/neo and pen/DHS intramammary treatments for clinical mastitis in dairy cows during the first 120 days of lactation. KEYWORDS: Dairy cow, mastitis, intramammary, antibiotic, treatment, somatic cell count.     

Effects of an additional nonsteroidal anti-inflammatory therapy with carprofen (Rimadyl Rind) in cases of severe mastitis of high yielding cows

This field study focuses on the possible effects of a combination of nonsteroidal anti-inflammatory treatment (carprofen) and a local and parenteral antibiotic on cure rates, survival rate and return to milk production of severe clinical mastitis cases. 69 cows in 3 herds (blocked by parity) with severe clinical mastitis during the first 120 d of lactation (median = 28 d) were treated with antibiotics and one-half of these cows were treated with 1.4 mg/kg bodyweight carprofen (Rimadyl Rind, Pfizer GmbH Tiergesundheit, Germany). Double milk samples for bacteriology were collected from clinically affected udder quarters before treatment and at 14 (+/- 3) and 21 (+/- 3) days after commencement of treatment for cytomicro-temperature, clinical, bacteriological, cytobacteriological cure rate and in the number of cows that were defined as treatment failures (i.e., died, re-treated, relapse). Six (22.2%) vs. seven (19.4%) cows in the carprofen and control groups failed, respectively. The milk yield was significantly higher in the carprofen-treated group compared with the control group after treatment. The present work gives first indications that treatment of cows with severe clinical mastitis with a combination of carprofen and antibiotics could result in a faster return to milk production compared to treatment with antibiotics alone. If this effect can be affiliated to the administration of carprofen alone has to be examined in further studies.     

Initial experience with the intravenous administration of colloidal carbon to cattle in relation to the incidence of mastitis

The influence was studied of intravenous application of colloid carbon to ten dairy cows of Bohemian Spotted breed in the seventh to eighth months of gravidity, as exerted on the health condition of mammary glands and on milk yield in the subsequent lactation. The cure consisted of three i. v. installations in 72-hour intervals; one dose contained 150 mg carbon in 20 ml of 20% glucose. No adverse by-effects were observed in the course of application and after it. During the subsequent lactation period (nine months) the test cows exhibited a better health condition of mammary glands if compared with the control group (ten dairy cows). In the test group no case was recorded of the clinical form of mastitis while in the control group one case of acute mastitis and two cases of chronic mastitis occurred. S. agalactiae was not isolated at all in the test group while in the control group it was isolated in two cows. S. aureus was also isolated more times (in 32 cases) in the control cows than in the test ones (in 27 cases). A higher average counts of cells in udder-quarter milk samples were found in the test group only at the onset of lactation (from the third month after calving), the average counts of cells over the whole period under study were however lower in the test group (1 380 000 per ml) than in the control group (1 234 000 per ml). The average daily milk yield per cow in the test group exceeded the average milk production in the control group in the period of study. An increase by 1.630 1 as compared with the untreated cow was observed in the average milk yield. It has been demonstrated by the results that by the intravenous instillation of colloid carbon nonspecific natural defensive mechanisms of dairy cows, mainly leucocytes, are stimulated, which enhanced the cell readiness to react to infectious process (mastitis) and overall injury of the organism (sepsis).     

Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows

The aim of this study was to evaluate the effect of postpartum mastitis between first calving and subsequent conception on production and reproduction performance as well as culling of Holstein cows. A data set of 9,183 first lactation cows was used. Results showed that the first cumulative 100?days' milk production and the milk yield standardized to 305?days were affected by the interval from calving to first mastitis (P??0.05). Calving year, calving difficulty score, and cumulative first 60?days milk production had significant impacts on mastitis risk (P?相似文献   

Resistance mechanisms of the bovine udder: new implications for mastitis control at the teat end

Investigations on bovine teat-end defenses and their role in mastitis control were reviewed. Alteration of teat canal keratin by method of intramammary drug infusion through the teat canal influenced the number of new infections. At the beginning of the nonlactating period, 2 methods of administering antibiotic were studied: full insertion of treatment syringe cannulas into teat cisterns and expelling contents and partial insertion of cannulas into the distal 2 to 3 mm of teat canals and slowly infusing contents. Partial cannula insertion reduced new infections by 50% and is an easily adopted management tool to reduce prevalence of mastitis. Intramammary devices used during lactation and the nonlactating period increased leukocyte concentrations in mammary secretions. An abraded polyethylene coil device reduced clinical mastitis and increased milk yield. Staphylococci colonize teat canal keratin and lacteal secretions of dairy heifers as early as 9 months of age, leading to intramammary infection at time of calving and persisting into lactation. Subsequent somatic cell counts are associated with milk production losses. Previously, such infections were shown to be associated only with older, mature animals.     

Growth and Development Symposium: Inflammation: Role in the etiology and pathophysiology of clinical mastitis in dairy cows

Genetic selection for increased milk production in dairy cattle was not associated with an attenuated inflammatory response. The systemic and local inflammatory responses contribute to altered metabolism, reduced production performance, and increased cull rate of lactating dairy cows with clinical mastitis. More aggressive inflammatory responses were observed during the peripartum period when compared with cows in late lactation after an intramammary challenge with purified lipopolysaccharide. The epidemiology of clinical mastitis indicates that the greatest incidence is observed during the peripartum period; therefore, an enhanced inflammatory response with concomitant suppression in other immune responses may be involved in the etiology and severity of the clinical mastitis observed in peripartum cows. Milk production losses and compositional changes are observed among all mammary quarters from a cow with clinical mastitis, but the responses are more severe and sustained among infected quarters. The infected mammary quarters reflect both the systemic and local reactions, whereas uninfected quarters represent only the systemic response. The systemic effects of the inflammatory response include reduced DMI, hyperthermia, and changes in whole-body nutrient partitioning affecting mammary epithelial substrate availability, whereas local inflammatory effects include energetic requirements of the increased inflammatory leukocyte pool, decreased synthetic capacity of mammary epithelium independent of substrate availability, and paracellular leakage of milk components from the alveolar lumen into the extracellular fluid. Research has focused on improving host immunological defenses, attenuating the inflammatory response, or improving the resolution of the disease state to limit the deleterious effects during clinical mastitis. This paper highlights the role inflammation plays in the etiology and pathophysiology of clinical mastitis as well as potential management strategies to reduce or prevent those losses.