Cost benefit analysis of lactation therapy with somatic cell counts as indications for treatment

Advances in Diagnostic Approaches and Therapeutic Management in Bovine Mastitis

Mastitis causes huge economic losses to dairy farmers worldwide, which largely negatively affects the quality and quantity of milk. Mastitis decreases overall milk production, degrades milk quality, increases milk losses because of milk being discarded, and increases overall production costs due to higher treatment and labour costs and premature culling. This review article discusses mastitis with respect to its clinical epidemiology, the pathogens involved, economic losses, and basic and advanced diagnostic tools that have been used in recent times to diagnose mastitis effectively. There is an increasing focus on the application of novel therapeutic approaches as an alternative to conventional antibiotic therapy because of the decreasing effectiveness of antibiotics, emergence of antibiotic-resistant bacteria, issue of antibiotic residues in the food chain, food safety issues, and environmental impacts. This article also discussed nanoparticles'/chitosan's roles in antibiotic-resistant strains and ethno-veterinary practices for mastitis treatment in dairy cattle.

Assessing Financial Impacts of Subclinical Mastitis on Colombian Dairy Farms

Bovine mastitis is a dairy cattle disease with high economic impact. Subclinical mastitis (SCM) contributes to most of the financial losses. Colombia dairy sector accounts for 2.3% of the gross domestic product (GDP) and 24.3% of the livestock GDP. Milk production reaches 6,500 million liters/year from nearly 500,000 cattle farms and is mainly based on small-scale production systems. This study evaluates the financial impact of SCM and the potential for its control in three dairy farm strata in a region in Colombia. The objectives of the study were 1) to determine the perception of farmers about the SCM problem on their farms, 2) to assess prevalence and financial impact of SCM on farms and in the "Area five" sanitary region of the Bogota plateau, and 3) to assess costs and effectiveness of control methods of SCM. Information about disease management and decision-making process was obtained through a participatory epidemiology workshop and applying a semi-structured survey. A two-stage stratified cross sectional epidemiological study was conducted on dairy cattle from a region with approximately 400 farms and 12,000 cows, with a sample size of 55 farms. Prevalence of SCM was calculated by defining a cow as positive for the disease when any quarter had a somatic cell count (SCC) higher than 250 × 10³ cells/ml. The prevalence of SCM in cows was 55.2%; significant differences were found between strata. Assessment of the financial impact of SCM in terms of milk losses was conducted using spreadsheet models. Milk production losses per farm ranged from 1.3% to 13.5%, and the economic impact in the region was estimated over USD $800.000 per year. The financial impact was greater in small- and medium-sized farms than large farms, and it was associated with the severity of SCC per quarter. Principal component analysis showed interactions, irrespective of the individual effect, and suggested three main groups of control interventions: application of basic milking hygiene practices, increase in the level of hygiene practices and veterinary advice, and SCM diagnosis and dry-cow treatment. Lack of information on management and production at farms promotes intuitive decision-making. Further research for the deeper understanding of intervention costs and effectiveness is suggested.

Treatment of mastitis in cattle

The understanding of mastitis, its cause, and the rationale for treatment or nontreatment of mastitis under various circumstances continues to evolve. This article presents research-based evidence about the use or nonuse of drugs to treat mastitis. Nondrug factors involved in decision making about mastitis, including cow characteristics and the epidemiology of mastitis, are also briefly discussed. This article provides information that helps in the making of knowledgeable, evidence-based decisions about therapy for mastitis. Focus is primarily on the use of antimicrobial drugs.

Diagnosis and treatment of subclinical mastitis in early lactation in dairy goats

The objectives of the study were to define the sensitivity and specificity of the California Mastitis Test (CMT) in determining the presence of intramammary infection in postpartum dairy goats and to determine whether antibiotic therapy increased bacteriological cure rate and lowered somatic cell count (SCC) compared with untreated controls. A CMT was performed and milk samples were collected for bacteriology from 211 glands of 106 does between 0 and 10 d after kidding. From a population of 3,239 glands from goats in 4 commercial herds, goats with one or both glands with a CMT score of >1 and from which bacteria were isolated were either assigned to be treated with 3 intramammary infusions at 12-h intervals of 75 mg of sodium ampicillin and 250 mg of sodium cloxacillin (n=57 glands) or left as untreated controls (n=49 glands). Milk samples were collected again 14 ± 3 and 21 ± 3 d later for bacteriology and SCC determination. Composite milk yield, goat SCC, length of lactation, and survival data were collected. A partial budget was constructed to assess the cost effectiveness of treatment. At a cut point of greater than trace, the sensitivity, specificity, and positive and negative predictive values of the CMT were 0.74, 0.74, 0.42, and 0.92, respectively. Treatment increased the bacteriological cure rate compared with no treatment [30/57 (53%) vs. 6/49 (12%)], but there was a pathogen by treatment interaction whereby treatment increased cure proportion in glands infected with minor, but not major, pathogens. Treatment reduced the foremilk gland-level SCC [1,595 (95% CI=1,106-2,300) vs. 3,028 (95% CI=2,091-4,385) geometric mean (× 1,000) cells/mL] but not the SCC at goat level [1,596 (95% CI=1,219-2,090) vs. 1,488 (95% CI=1,132-1,955) geometric mean (× 1,000) cells/mL] compared with no treatment. Milk yield, risk of removal from the herd, and length of lactation were not altered by treatment. Treatment resulted in a loss of NZ$20.39/doe. It was concluded that use of the CMT as a screening test resulted in a higher likelihood of finding a gland that would be infected than selecting a gland at random. Treatment increased bacteriological cure rate and reduced SCC at gland level compared with no treatment. However, at goat level, milk yield, SCC, and survival were not altered, resulting in no economic benefit of treatment.

Treatment of mastitis during lactation

Treatment of mastitis should be based on bacteriological diagnosis and take national and international guidelines on prudent use of antimicrobials into account. In acute mastitis, where bacteriological diagnosis is not available, treatment should be initiated based on herd data and personal experience. Rapid bacteriological diagnosis would facilitate the proper selection of the antimicrobial. Treating subclinical mastitis with antimicrobials during lactation is seldom economical, because of high treatment costs and generally poor efficacy. All mastitis treatment should be evidence-based, i.e., the efficacy of each product and treatment length should be demonstrated by scientific studies. Use of on-farm written protocols for mastitis treatment promotes a judicious use of antimicrobials and reduces the use of antimicrobials.

Therapeutic effects of systemic or intramammary antimicrobial treatment of bovine subclinical mastitis during lactation

The short- and long-term treatment efficacy of administrating penicillin for bovine subclinical mastitis during lactation when using intramuscular (IM; 9.5 mg [15,000 IU]/kg bodyweight of benzyl penicillin potassium) injections twice daily for 5 days, or intramammary (IMM; 0.3g [300,000 IU] penethamate hydroiodide) administration once daily for 5 days was compared with a control group receiving no treatment. One hundred and twenty-six cows met the inclusion criteria, which were lack of clinical symptoms, no recent treatment with antimicrobials, and findings of penicillin-sensitive Staphylococcus aureus, Streptococcus dysgalactiae, or Streptococcus uberis in combination with an inflammatory reaction. At follow-up 42-58 days after treatment, the proportion of cows negative for the original infection was significantly higher in IM and IMM groups compared to controls, but the difference between antimicrobial treatment groups was not significant. The udder quarter milk somatic cell count (SCC) was significantly lower at follow-up in IM and IMM groups than in controls, but milk production did not differ between treatments. The culling rate during the 10-month period following treatment was significantly higher in the group treated with IMM penicillin than in the other two groups, but the risk of new mastitis treatments within 10 months did not differ between the three groups. The cure rate was significantly affected by lactation number (lower in older cows), breed (lower in the Swedish Holstein breed), pathogen (lower for S. aureus), and pre-treatment SCC (higher for above average SCC). In conclusion, beneficial long-term effects of antimicrobial treatment during lactation of subclinical mastitis caused by S. aureus, Str. dysgalactiae or Str. uberis were not found in the present study.

A Partial Budget Model to Estimate Economic Benefits of Lactational Treatment of Subclinical Staphylococcus aureus Mastitis

Subclinical Staphylococcus aureus mastitis is rarely treated during lactation because it is widely believed to be uneconomical, although there are no economic studies that support this view. Partial budgeting was used to develop a deterministic simulation model to estimate the net cost or benefit of antibiotic treatment of subclinical S. aureus mastitis during lactation. Direct and indirect effects of treatment were taken into account, including prevention of clinical flare-ups and contagious transmission. Input variables were based on literature and on 2003-2004 prices in the Netherlands. When contagious transmission of S. aureus was likely (reproductive ratio R = 5.3), 3- and 8-d treatments resulted in an average net profit of 95.62 euros and 142.42 euros, respectively, compared with no treatment. When the probability of S. aureus transmission was low (R = 0.32), the average economic benefit of 3- or 8-d treatment was -21.12 euros and -57.70 euros, respectively. On low-transmission farms, 3-d treatment was profitable when the appropriate cows were selected for treatment using known risk factors for cure. Sensitivity analysis showed that the 6 most influential input variables in the model were chance of bacteriological cure, R, probability of culling, retention pay-off, and cost of antibiotics and bacterial culture. Although the economic outcome of lactational treatment of subclinical S. aureus mastitis is highly herd-, cow-, and strain-dependent, treatment is economically justified in many situations.

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 dollars 29.1 in dairy herds in secondary towns (DHIST) to US dollars 66.6 in UDF. A total loss of US dollars 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 dollars 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.

Antibioticoterapia para controle da mastite subclínica de vacas em lactação

Avaliou-se a eficiência da antibioticoterapia como estratégia para o controle de mastite subclínica em animais em lactação. Foram tratados 83 tetos infectados de 31 animais de três propriedades leiteiras, divididos em dois estádios da lactação:15 a 100 dias (grupo I) e 101 a 200 dias (grupo II), com aplicação intramamária de 250mg de cefacetril sódico (cefalotina). A droga permaneceu 24 horas dentro dos quartos do úbere dos animais tratados. Vinte e oito tetos de 14 animais infectados foram mantidos como controle, sem tratamento. Os grupos tratados e controle foram avaliados nos dias zero, 14, 25 e 40 após o tratamento por meio de provas de California Mastitis Test (CMT), contagem de células somáticas (CCS), isolamento e identificação de patógenos e produção leite. Staphylococcus aureus e Staphylococcus coagulase-negativo foram os microrganismos mais isolados (43,1%), seguidos por Bacillus spp, Corynebacterium bovis, Streptococcus uberis e Escherichia coli. Quatorze dias após o tratamento houve redução de 61,4% das infecções intramamárias e acentuada diminuição da CCS e de reações positivas ao CMT nos animais tratados, nos dois estádios da lactação. Entre os dias 25 e 40 após tratamento as diferenças não foram significativas (P> 0,05). Ocorreram recidivas ou reinfecções nos tetos tratados. O aumento de produção de leite não foi significativo entre os animais tratados (P> 0,05). A antibioticoterapia durante a lactação não foi efetiva para o controle das mastites subclínicas, mesmo em animais que apresentaram alta contagem de células somáticas.

Environmental gram-positive mastitis treatment: in vitro sensitivity and bacteriologic cure

A clinical trial was conducted in a large dairy herd to determine the efficacy of intramammary pirlimycin hydrochloride administration during lactation for bacteriologic clearance of gram-positive environmental clinical and subclinical mastitis infections. Quarters infected with environmental streptococci that received pirlimycin therapy (13/28) were 1.8 times more likely to resolve infection than untreated quarters (5/14). The small numbers of quarters infected with coagulase-negative staphylococci resulted in inadequate power to assess treatment differences in cure rate. Although the association was not statistically significant, quarters from cows with sensitive environmental streptococci isolates from composite samples (8/13) resolved infection with treatment at approximately twice the rate of treated quarters with resistant isolates (3/10).

A clinical trial to evaluate the effectiveness of antibiotic treatment of lactating cows with high somatic cell counts in their milk

OBJECTIVE

To determine the effectiveness of treatment of lactating cows with high somatic cell counts in milk.

DESIGN

Randomised clinical trial.

METHODS

Single pooled quarter samples of milk were obtained from cows with somatic cell counts above 500,000 cells/mL on fifty farms. Milk samples were cultured for known mastitis bacterial pathogens. Cows were randomly allocated to treated and untreated groups. Treated cows received both intramammary cloxacillin and parenteral erythromycin. Single pooled quarter milk samples were obtained at 6 weeks after treatment and were cultured for the presence of pathogenic bacteria. The percentage of samples with no growth at the post-treatment culture was used as an estimate of the bacteriological cures for each pathogen type and for each treatment group. Somatic cell counts of cows were compared between treatment groups and within pathogen group. The number of cows that completed a full lactation were compared between each treatment group and within each pathogen group.

RESULTS

Treatment had no effect upon bacteriological cures, irrespective of pathogen present or the presence of bacteria during the previous lactation. There was no effect of treatment upon somatic cell count except for cows infected with Streptococcus dysgalactiae in which treatment caused a significant lowering of cell counts. This effect was not present in the subsequent lactation. Treatment of chronically infected cows did not alter the probability of a cow completing a full lactation but did improve the probability of newly infected cows being retained for the next lactation. Twenty-eight of 214 treated cows developed clinical mastitis in more than one quarter after treatment, thus indicating a poor technique by farmers for the insertion of intramammary antibiotics.

CONCLUSIONS

Treatment during lactation of cows with high somatic cell counts in milk is ineffective in reducing bacterial infections and in reducing somatic cell counts to acceptable numbers.

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.

Economics of mastitis and mastitis control

Mastitis is the most costly disease of dairy cows. The major economic loss of all forms of mastitis results from reduced milk production. Because of the difficulty in controlling environmental mastitis organisms, mastitis will maintain this role in the foreseeable future.

New technologies and decision making in high producing herds

New technologies have evolved for improved management of on-farm records and their use in decision making. Computerized on-farm record systems, coupled with automated monitoring of individual animal performance and electronic transfer of data between the on-farm database and mainframe systems, have enhanced the capability for herd management. Electronic aids for decision making may be embedded into on-farm management programs to allow more detailed data to be available with ease and convenience. Technological advances and their application toward improved operational decisions concerning production monitoring, reproductive management, genetic improvement, feeding, and health in a 300-cow dairy herd are presented as examples. Substantial advances have been made in technologies that improve management and decision making. Evolving technologies promise to enhance further the capabilities for improved management and decision making in high producing herds.

Comparison of probiotic and antibiotic intramammary therapy of cattle with elevated somatic cell counts

The effects of treating subclinical mastitis with intramammary infusions of either a Lactobacillus or an antibiotic preparation on intramammary infection cure rate and on milk SCC were compared. Cows with two consecutive monthly DHIA composite SCC greater than 300,000 cells/ml (5.4771 log10/ml) were defined as high SCC cows. Twenty-six subclinical cows were randomly assigned to one of two treatments. Quarter foremilk samples were obtained from all quarters at d 0, 7, and 14 following infusion to determine the microbiological status and SCC. Composite milk SCC were determined monthly by DHIA and at d 0, 7, and 14 of the study. Coagulase-negative staphylococci were the predominantly isolated pathogens. Treatment of cows with Lactobacillus cured 21.7% of infected quarters, whereas 73.7% of infections treated with antibiotic were eliminated. Treatment of quarters with antibiotic did not reduce quarter SCC unless infected quarters were cured. Intramammary infusion of quarters with Lactobacillus increased quarter SCC, mainly because of an increase in SCC of initially uninfected, low SCC quarters. Monthly composite SCC were similar between treatments. The results indicate that administering Lactobacillus or antibiotic treatment to all quarters based on elevated composite SCC should not be adopted. Lactobacillus treatment increased SCC with no effect on infection rate.

Effectiveness of intramammary antibiotic therapy based on somatic cell count

The Virginia Tech dairy herd was used in a 10-mo study to determine the effect of intramammary antibiotic therapy of quarters with elevated SCC on milk production, subsequent DHIA SCC, and infection status. Cows were assigned randomly to experimental or control groups. Animals in both the control and experimental groups with SCC scores greater than or equal to 5 for the first time during that lactation were quarter sampled, milk was cultured to detect presence of mastitis pathogens, and SCC was determined. All experimental cows with quarter SCC greater than or equal to 5 were treated with an intramammary cephapirin product only in those elevated quarters (DHIA SCC greater than or equal to 5), regardless of clinical symptoms. Control cows received antibiotic therapy when symptoms were clinical, regardless of SCC. Treatment group had no significant effect on milk production, SCC, or infection status of the cow. Treatment of cows in the experimental group cured 70% of infected quarters, whereas only 50% of infections in the control group were eliminated.

Use of dairy herd improvement somatic cell information by Ohio dairy producers and their perceptions of mastitis

A telephone survey was conducted of 149 current recipients of the Ohio DHIA SCC option, 30 past recipients of the SCC option, and 30 producers who had never received the SCC option. Producers were questioned to ascertain their knowledge of mastitis, how they used SCC information, their treatment and prevention of mastitis, and their use of veterinary services. Producers' perceptions of mastitis indicated a high awareness of the consequences of mastitis. However, 10% of producers on DHI still did not practice postmilking teat dipping, and 16% did not handle mastitic cows any differently during milking. Current recipients of SCC data used the data more frequently than did past recipients of the SCC data to evaluate mastitis treatment or control, choose cows to cull, identify cows to dry off early, indicate herd infection, and evaluate mastitis control. The major reason given by nonrecipients for never having enrolled in the SCC program was that they did not perceive a need for it. Further educational programs explaining SCC and its use to producers seems warranted.

The potential use of cell count linear scores in veterinary herd health and production control on dairy farms. A preliminary report

Subclinical mastitis is a major problem in udder health control. Reduction of this infection is hard to achieve because subclinical mastitis is not obvious to the farmer. This study examined the value to the farmer of regularly supplying somatic cell counts from individual cows for the control of subclinical mastitis. The use of linear scores, i.e. logarithmic transformations of cell counts, appeared to be appropriate when combined with other relevant information on udder health and included in a herd health computer programme.

Effective use of dairy herd improvement somatic cell counts in mastitis control

The single most important factor affecting somatic cell count in milk is mammary gland infection status. In comparison, all other factors are minor. Consideration needs to be given to diurnal effects on Dairy Herd Improvement a.m.-p.m. sampling schemes. Somatic cell count linear score of 5 (283,000) appears to be a good choice of threshold for mastitis control applications. A greater understanding of the nonbacteriological factors affecting somatic cell count is needed so that relative thresholds could be used to improve the clarity of somatic cell count interpretation. Linear score loss estimates are effective educational tools providing motivation for mastitis control implementation. Infection status or milk loss estimates based on single somatic cell count tests on individual cows are weak. A lactational average linear score on individual cows or linear score compilations across a herd provide credible estimates. Treatment of subclinical mastitis based on somatic cell count levels is not economically beneficial and is not recommended. Usefulness of Dairy Herd Improvement somatic cell count data as a mastitis management tool requires measures of mastitis level, new infection rate, and mastitis pattern within the herd over time.

Animal health and management and their impact on economic efficiency

Relationships between animal health and economic efficiency were examined using data from genetic investigations and management studies. Genetic investigations have indicated that cows bred for high production do require more health care, but that increased costs for health care negate only a small fraction of the greater returns from cows that are genetically superior for yield traits. These same studies have identified age of cow and stage of lactation as important sources of variation in health care costs. Health care costs increase with age and are highest at parturition and immediately thereafter, and decrease to much lower levels as lactation progresses. Animal health issues considered from a management perspective were macro-environment (climate, housing, facilities), nutrition-reproduction complex, replacement management, mastitis and udder health, and herd health preventive medicine programs. Most advances in management of animal health were beneficial, but some are economical only for large herds. Improvement of udder health through continued and expanded research on milking procedures and equipment design is an area of unusual promise. Additional research appears needed to cope with stress and fatigue to legs and feet in modern facilities. Preventive medicine programs become more cost effective as herds become larger and should be used by a larger percentage of dairy producers. The economic efficiency of many management practices is uncertain due to a paucity of data. Animal scientists should plan to incorporate economic comparisons into much more of their research.