Wisconsin Mastitis Test Scores Research Articles

Radiotelemetry temperature responses of mammary gland and body to intramammary injection of Escherichia coli endotoxin or Streptococcus agalactiae in lactating dairy cows

Summary To investigate the feasibility of using changes in body or mammary temperature to detect mastitis, radiotransmitters were implanted midway between rear udder quarters and in the peritoneal cavity of 5 Holstein cows (1 to 3 months in lactation) housed in an environmental chamber (16 ± 2 C; lights on 7:00 am to 11:00 pm). After a 6-week control period, Escherichia coli endotoxin (0.5 mg) was injected after the morning milking into left rear teat cisterns via the teat canal. Wisconsin mastitis test score and somatic cell count in all quarters increased significantly (P < 0.01) by the next milking. Effects were greatest in the endotoxin-exposed quarters. Milk yields for all quarters decreased significantly (P < 0.01) by the first milking after endotoxin injection. Udder and body temperatures at milkings were similar and were not affected by treatment. When temperatures were averaged for the 5 cows for each of 120 time points/d, average temperatures, relative to time of injection of endotoxin, were increased by 0.5 C above baseline at 2.75 hours, peaked at +2.9 C at 6.50 hours, and remained high through 9.25 hours after injection. Power spectra calculated for individual cows on a daily basis universally indicated an increase in power at low frequencies on the day of injection. Subsequently, Streptococcus agalactiae (200 colony-forming units) was injected into right rear teat cisterns. Wisconsin mastitis test score increased at the second milking after injection. Cell count and quarter milk yield decreased by the third milking. As with endotoxin, injection of S agalactiae could not be detected via a change in temperature at milkings. Of the 5 cows, 3 had a peak in temperature after injection of S agalactiae. Average temperatures for these 3 cows relative to time of injection, were increased by 0.5 C above baseline at 24.25 hours, peaked at + 1.4 C at 26.25 hours, and remained high through 28.75 hours after injection. Power spectra calculated for the day in which a temperature peak was detected for these 3 cows indicated an increase in power at low frequencies, compared with spectra for all other days. Similar increases in power were also detected for the 2 cows that did not have temperature peaks. When clinical signs of mastitis are obvious at milking, there is little advantage of using body temperature for detection of infection. When clinical signs are not obvious, body temperature is often only minimally increased. Thus, monitoring body temperature at milkings adds little to the ability to detect mastitis. Of more interest is the ability to detect transient temperature increases that often develop in association with less-severe infections. Also, as early treatment increases the likelihood of successful treatment, detection of the onset of temperature increases would be advantageous for treatment of severe infections. Detection of a transient temperature peak requires taking temperature readings every 2 hours. To detect mastitis when a temperature peak does not occur requires measurement every 15 minutes to calculate power spectra. The ability to detect the onset of acute clinical infections and subclinical infections, using frequent temperature readings, indicates that development of a practical radiotelemetry system for use on farms may be warranted, depending on cost. The added potential of using body temperature to monitor general health and to detect estrus enhances the economic feasibility of developing such a system.

Relationship of In Vitro Immune Function with Health and Production in Holstein Cattle

Eighty-seven lactating Holstein cows from the Iowa State University Breeding Research Herd were evaluated for 20 in vitro measures of immune function. Principal component analysis was used to discard redundant assay variables such that the 11 remaining variables were more nearly independent than the original variables. Multiple linear regression in an animal model was used to determine the effects of these 11 variables on lifetime production and on general, udder, and reproductive health traits. A significant joint effect of the 11 immune function variables on California mastitis test scores was observed. California mastitis test scores were positively correlated with antibody-dependent neutrophil cytotoxicity and negatively correlated with antibody-independent neutrophil cytotoxicity. Wisconsin mastitis test scores were also positively associated with antibody-dependent neutrophil cytotoxicity. Cytochrome c reduction was negatively associated with mammary and total health costs. A positive relationship between clinical mastitis and discarded milk and IgG2 was observed, and IgG1 was associated with increased quarter California mastitis test scores and increased production. Thus, certain in vitro immune function assays may serve as indicators of susceptibility to health problems in dairy cattle, particularly for traits associated with udder health.

Association of Class I Bovine Lymphocyte Antigen Complex Alleles with Health and Production Traits in Dairy Cattle

Ninety-eight Holstein cows from the I-O-State breeding research herd were serologically typed for class I bovine lymphocyte antigens. After exclusion of animals carrying alleles that occurred at frequencies lower than 4%, records from 82 cows that had 161 lactations remained for analysis of major histocompatibility complex allelic effects. A gene substitution model was used to evaluate the additive effects of nine alleles (frequencies of 4 to 20%) at the bovine lymphocyte antigen complex A locus on general health, udder health, and production traits. Allele w14(w8) was associated with decreased quarter milk sample California Mastitis Test scores, composite milk sample California Mastitis Test and Wisconsin Mastitis Test scores, decreased total health costs, and with increased milk yield, fat yield, fat percentage, and income over feed costs. Allele w11 was associated with decreased clinical mastitis, discarded milk, and udder health costs but was also associated with decreased fat yield, fat percentage, and income over feed costs. Allele w31(w30) was associated with decreased fat percentage. These relationships suggest that alleles at the bovine lymphocyte antigen complex A locus may serve as markers for health and production traits. Thus, the potential may exist for enhancement of disease resistance or production in cattle via marker-assisted selection and genetic manipulation techniques using class I genes of the bovine major histocompatibility complex.

Effects of Intermittent Electrical Shock on Responses Related to Milk Ejection

Electrical shock is perceived to be a problem on many dairy farms. Thirteen cows were subjected to intermittent electrical shock (5s on, 25s off) at a.m. and p.m. milkings for 7 days. Seven cows were subjected to 3.6mA shocks starting with preparation (1min udder wash and dry) and six cows to 6.0mA. One additional cow initially in the 6.0mA group had to be removed from the study because of severe behavioral responses to shock. Compared to 5-day preshock and postshock periods, milk yield, milking time, and Wisconsin Mastitis Test scores were not affected by shock. Maximum rate of milk flow increased slightly. The number of behavioral events such as lifting legs during milking increased with a greater increase in the 6.0mA group. Heart rate was elevated (+3 beats/min) only in response to shock during preparation (initial shock). For selected days, time to peak oxytocin response was delayed in the 3.6mA group, and peak prolactin and area under prolactin response curves increased similarly for both groups during shock. There were significant a.m.–p.m. differences in milk yield, milking time, maximum rate of milk flow, heart rate, and responses of oxytocin and prolactin.We think that milk yield can be maintained, at least in the short term, in cows subjected to electrical shock due to power-line problems if dairy producers take exceptional care to accommodate behavioral responses.

Group-Fed Concentrate-Silage Blend Versus Individually-Fed Concentrates and Group-Fed Silage for Lactating Cows

System A provided 7.26kg concentrate per cow daily blended and group fed with silage in 125 total and 97 selected 305-day lactations. System B provided concentrate hand-fed according to each cow's daily production (1kg concentrate/3.25kg milk) separate from group-fed silage in 112 total and 75 selected 305-day lactations. The 305-day records excluded those containing more than 150 days open. Both groups had, when available, 2.27kg hay/cow daily or limited and equal grazing. Combined refusals, 5 to 10% of concentrate-silage blend in A and 5 to 10% of silage in B, plus fresh silage and 2.27kg concentrate/cow daily constituted the common dry cow ration. Milk, milk fat percentage, and 4% fat-corrected milk, respectively, were 6,475kg, 3.80%, and 6,270kg in A and 6,899kg, 3.69%, and 6,566kg in B in the total lactations and 5,900kg, 3.78%, and 5,686kg in A and 6,098kg, 3.70%, and 5,818kg in B in the selected 305-day lactations. Percentages of solids-not-fat and protein in the milk were similar between A and B. Excluding grazing inputs, fat-corrected milk per total digestible nutrients per total lactation was 1.73kg in both systems. Days open, days in milk, mean Wisconsin Mastitis Test score, body weight, net weight change, days to peak daily milk yield, days to minimum body weight, and minimum body weight were not different between systems in either the total or the selected 305-day lactations. Involuntary culling and culling for low production terminated 18 and 17% of the lactations started on Systems A and B.

Effect of Escherichia coli endotoxin-mediated inflammation of one mammary quarter of the bovine udder on diapedesis into other quarters.

Implantation of 1 microgram Escherichia coli endotoxin into one papillary duct of a bovine udder frequently resulted in a mild inflammatory process in the treated quarter which was measured by use of the Wisconsin mastitis test (WMT) on quarter fore milk samples. Inflammation of a fore quarter was usually (18/24) accompanied by a transient elevation in WMT score from the homolateral hind quarter, but rarely (1/25) from the contralateral quarter. Inflammation in a hind quarter rarely (2/26) affected the homolateral fore quarter and never (0/25) the contralateral quarter. The pattern of responses suggests tha absorption and initial removal of endotoxin from the mammary gland occurs via the lymphatic rather than the blood system.

Effects of Vacuum and Pulsation Ratio on Udder Health

Effects of vacuum and pulsation ratio on udder health were studied for 36 first parity animals in a 60-day trial. Treatments consisted of vacuum at 33.3, 41.6, and 50 kPa at pulsation ratios of 50:50, 60:40, and 70:30 at 60 pulsations per min. All teats were exposed to a culture broth of Staphylococcus aureus after machine removal. Numbers of intramammary infections and somatic cells were determined. Analysis for number of intramammary infections indicated no significant differences among treatments for number of infected available quarters. Trend for intramammary infections was that as pulsation ratio widened, the number of infected available quarters increased, especially at the ratio 70:30. As vacuum increased, number of infected available quarters increased. Least squares means of Wisconsin Mastitis Test scores were 6.29, 5.57, and 6.68 for 33.3 kPa; 12.18, 3.82, and 7.86 for 41.6 kPa; and 9.11, 6.40, and 15.02 for 50 kPa at pulsation ratios 50:50, 60:40, and 70:30. There were significant differences among treatments for vacuum and pulsation ratio. Wisconsin Mastitis Test data indicated an interaction between vacuum and pulsation ratio. Optimum predicted vacuum and pulsation ratio based on Wisconsin Mastitis Test data were 27.2 kPa and 62:38.

Effectiveness of Educational Efforts in Implementing Mastitis Control Procedures in Commercial Dairy Herds

One hundred-fifty dairymen in northeastern Ohio, whose herds had a history of persistently high Wisconsin Mastitis Test scores, were invited to participate in this project, with 43 agreeing to do so. These dairymen were divided into two experimental groups and one control group to determine the effectiveness of two intensities of educational effort on adoption of mastitis control procedures and to demonstrate the effectiveness of mastitis control recommendations. A teat dipping and dry cow therapy program was adopted by more herds in the group with intense educational effort than in the intermediate or control group. Per-cents of herds in each group utilizing this program in 1977 (start of project), 1978, and 1979 were 8, 75, and 92 for the intense group; 30, 50, and 50 for the intermediate group; and 10, 27, and 27 for the control group. Prevalence of infection declined more rapidly in the intense group with 42, 28, and 24% of cows infected; 39, 25, and 30% in the intermediate, and 56, 35, and 42% in the control group in 1977, 1978, and 1979. Those herds adopting a teat dipping and dry cow therapy program had infection pevalence of 41, 25, and 20% of cows; bulk tank Wisconsin Mastitis Test scores of 15.5, 14.7, and 11.4; and milk production per cow per day of 18.4, 18.4, and 17.5kg in 1977, 1978, and 1979.

Variation in Wisconsin Mastitis Test Scores of Bucket Milk Samples and Relationship to Bacterial Infections

Sources of variation in the Wisconsin Mastitis Test were studied in 4739 bucket milk samples from 111 cows in one herd during 103 days. Quarters of cows were classified infected or uninfected through bacteriologic assays of quarter milk samples. Quarters were uninfected in 70.4% of the cow-quarter-days and infected with Staphylococcus aureus and Streptococcus agalactiae in 1.4 and .9% of the quarter samples. Scores of all cow-days averaged 8.5. Wisconsin Mastitis Test scores of cow-days having no pathogens averaged 5.8. Correlation of duplicate samples was .97. Repeatability of monthly tests was .67. Days within month of lactation, month within age group, cow within age, and differed. Older cows averaged higher Wisconsin Mastitis Test scores. Scores for uninfected cow-days did not differ with age. Scores were higher by 5.5 units in cows with infected quarters than in those with no infected quarters. The increase was greater with S. aureus or S. agalactiae present than with less virulent pathogens. In a cost-utility analysis, Wisconsin Mastitis Test was inefficient in detecting infected cows with a single test.

Two-year survey of five herds with high Wisconsin Mastitis Test scores

The first objective was to measure the effectiveness of mastitis control practices in herds with high WMT scores.
 The second objective was to measure the effectiveness of 400 mg of novobiocin when used as the nonlactating period infusion component of the program, when novobiocinpenicillin was routinely used for intramammary infusion of infected lactating glands.
 A third objective, in the event a herd did not respond, was to attempt to learn the reason or reasons for this failure.

Feeding and Managing Dairy Cows in Three versus One Production Group

Lactating Guernsey and Holstein cows were assigned randomly to either a statified here with high, medium, and low production groups or a one-group control herd. Complete rations were formulated to meet National Research Council requirements for average milk production of the group (medium and low) or group average plus 10% (high and control). Cows in the stratified herd were regrouped at monthly intervals.Mean body weights and average daily intakes of hay, silage, and concentrate over 3 yr were similar between treatments. Stratified and control herds did not differ significantly in milk production adjusted for age and season, fat, or reproductive performance. Stratified Guernsey in first lactation produced more milk and required fewer services per conception than controls. Lactation persistency of cows in the stratified herd was unaffected by intergroup transfer. Stratified cows had higher mean monthly Wisconsin Mastitis Test scores.

Quarter Milk Variation in Immunoglobulins and Ability to Support Phagocytosis

Milk samples were collected from two quarters in each of 8 cows that had Wisconsin Mastitis Test scores of less than 8.0. After letdown was stimulated, 35ml of foremilk, the sixth 35ml (middle milk), and 45ml of strippings were collected by hand. Measured on each fraction were immunoglobulins, serum albumin, total protein, pH, percentage fat, Wisconsin Mastitis Test, and the ability of skim milk and whole milk to support phagocytosis of Staphylococcus aureus by isolated donor milk neutrophils. Foremilk and middle milk differed in immunoglobulin M (.014 to .018 mg/ml) and in the ability of whole milk to support phagocytosis (32 to 28% S. aureus phagocytosed). The following measures differed from middle milk to strippings: immunoglobulin A (.063 to .083 mg/ml); immunoglobulin G1 (.238 to .302 mg/ml); immunoglobulin M (.018 to .023 mg/ml); fat (3.9 to 7.4%); and Wisconsin Mastitis Test (5.0 to 9.2). Immunoglobulin G2, bovine serum albumin, total protein, pH, and the ability of skim milk and whole milk to support phagocytosis did not change. Although small differences may exist between foremilk and middle milk, foremilk gave reliable estimates.

THE PREVALENCE OF UDDER INFECTION AND MASTITIS IN HERDS PRODUCING BULK MILK WITH EITHER CONSISTENTLY HIGH OR LOW CELL COUNT

Quarter samples from twenty-five dairy herds, representing 223 herds supplying direct to Brisbane, were cultured and submitted to the Wisconsin Mastitis Test (WMT). Thirteen herds had a history of producing bulk milk with a consistently high WMT score (greater than 15 mm) and in twelve herds the WMT score was consistently low. Prevalence of infection was higher in group A herds (22.2% quarters were infected with Staphylococcus aureus or streptococci) than in group B herds (9.8% of quarters were infected). There was considerable scatter of prevalence among both groups of herds. Overall, S. aureus was found in 19% of cows and 7% of quarters, and Streptococcus agalactiae in 15% of cows and 7% of quarters. Quarters from group A herds showed a higher WMT score than those in group B herds whether infected with S. aureus, Str. agalactiae, micrococci or yielded no detectable organisms. It was concluded that regular surveys are required of the high cell count herds to monitor mastitis status in the industry.

Eliminating Stripping in Machine Milking

Cows were divided into two groups to evaluate consequences of eliminating stripping from milking. The seven control cows were machine stripped in the normal manner, but the machines were removed from the nine experimental cows as soon as a sensor indicated flow less than .5 kg/min. Cows in the stripped group averaged .7 kg/milking more than those not stripped. The differences between the two groups diminished as lactation progressed. The small but significant interaction of treatment by stage of lactation indicated that cows not stripped were more persistent. Cows in the stripped group had more mastitis as indicated by the higher Wisconsin Mastitis Test scores and greater amounts of milk discarded.

The Automated Pyruvate Method as a Quality Test for Grade A Milk

Concentrations of pyruvate in Grade A raw and pasteurized milks were determined by an automated procedure. The method was sensitive to 0.1 mg of pyruvate per liter and the coefficient of variation of the method was 1.6% for a sample of milk containing 3 mg/1. Since about twice as much pyruvate was produced in samples incubated 24 h at 20 C compared with 15 C, the higher temperature is suggested for the pyruvate difference test (ΔP); however, psychrotrophs would more likely be detected with an incubation temperature of 15 C. Pyruvate difference tests of pure cultures in steamed milk distinguished between concentrations approximating 102 and 103Pseudomonas fragi, 103 and 104Pseudomonas fluorescens, and between 104 and 105Escherichia coli, Streptococcus faecalis, Lactobacillus acidophilus and Micrococcus luteus, but did not distinguish between 104 and 105 initial concentrations of six other gram-positive bacteria and Salmonella typhi. Both the initial pyruvate (IP) concentration and the ΔP in raw milk were correlated with the logarithm of the Wisconsin Mastitis Test score, suggesting that somatic cells contribute to pyruvate content. Correlations of IP and ΔP with Standard Plate Counts of raw and pasteurized milks were low or insignificant and only with raw milk from normal quarters was there a significant correlation of IP and ΔP with initial Psychrotrophic Plate Counts (PPC). Rates of pyruvate production by pure cultures in steamed milk and by the mixed natural flora of pasteurized milk were consistent with rates of growth. However, certain psychrotrophic bacteria reduced the concentration of pyruvate to undetectable levels after producing 10 or more mg/1. Suggestions are made regarding applicability of the test in controlling keeping quality of pasteurized milk and in receiving of bulk raw milk.

Evaluation of a Hygiene and Dry Period Therapy Program for Mastitis Control

In two trials half of the cows were subjected to a postmilking test dip and and dry period therapy of all quarters while the other half were untreated controls. In the first trial involving 120 cows over 2 years the proportion among treated cows of quarters infected with Streptococcus agalactiae decreased from 21.8 to 1.6% and with Staphylococcus aureus from 9.5 to 2.9% whereas controls showed much smaller changes. The new infection rate was 1.03 infections per cow-year in treated cows and 1.50 in controls. Clinical mastitis was not reduced in treated cows due in part to an increase in coliform infections. Wisconsin Mastitis Test scores of quarter samples were significantly reduced in treated cows.The second trial involved 80 cows over 60 weeks; these cows had a low initial intramammary infection. Among treated cows S. agalactiae infection, new infection rate, and cases of clinical mastitis were reduced from controls, and there was no increase in coliform infections.

Relation of Milk Fat-Depressing Rations and Subclinical Mastitis to Milk Proteins

Two continuous feeding trials involving 28 cows were used to study the influence of a pelleted, high-grain ration, of dietary supplementation with unsaturated oils (safflower and cod liver oil), and of subclinical mastitis under these conditions, on milk total proteins, casein, whey proteins, solids-notfat (SNF), and fat. Milk samples from 512 udder quarters were analyzed. Total milk protein and casein contents were elevated by each nutritional regime. Whey protein and SNF contents increased while feeding the high-grain ration, but both showed only minor changes during the oil supplementation. A net gain in milk protein synthesis of 15% was obtained during the high-grain regime, but protein yields during the oil regime were lower because of reduced milk production. Milk fat percentages and fat yields were depressed by each regime.Ratios of casein content to total protein content of milk were significantly related to Wisconsin Mastitis Test (WMT) scores (r = —0.45). Intraclass correlation coefficients within udder quarters for WMT scores on whey protein per cent, SNF per cent, casein yield, milk yield, total protein yield, fat per cent, casein per cent, whey protein yield, and total protein per cent were, in decreasing order, 0.45, —0.41, —0.34, —0.33, —0.29, —0.19, —0.18, —0.14, and 0.08, respectively.

Relationships Between Wisconsin Mastitis Test Scores and Cell Counts in Milk

Wisconsin Mastitis Test (WMT) scores and cell content were determined on milk samples of quarter and tank origin over a period of five days. Wisconsin Mastitis Test scores utilized for analysis ranged from 4 to 34 and cell content of the samples from 87,000 to approximately 4million per ml.The relationship between WMT score and cell content was the same for milk of quarter or tank origin when the samples were of similar age, except possibly for tank milk collected on a 48-hr pickup schedule.A direct relationship between WMT score and cell content was obtained when the cell content, divided by 105, was converted to its common logarithm and then plotted against the WMT score. The conversion of WMT score to cell content as originally suggested was found to underestimate the cell content of the sample by approximately 38%. Our best estimate of the line of regression for WMT scores on cell content of milk 0–24 hr old is YWMT = 0.352 + 21.17 log10 (cells×10−5).Wisconsin Mastitis Test score and cell content of milk did not decrease proportionately with age of milk and scores decreased faster than cell numbers. Therefore, the estimated line of regression for fresh milk cannot be used for milk older than 24 hr, if an estimate of the original cell content of the milk is desired. The regression line YWMT = −.231 + 19.51 log10 (cells×10−5) is our best estimate for converting WMT scores of milk between 25 and 48 hr old to cell content at time of milking.Additional regression lines are presented for older milk and for comparison between laboratories. Implications of the changing relationship between WMT score and cell content of milk samples are discussed.

Effect of Milk Age, Storage, and Testing Temperatures upon the Wisconsin Mastitis Test Score

Wisconsin Mastitis Test (WMT) scores were determined on milk samples of varying cell counts for five days. The samples were subjected to different conditions of storage and testing, and irrespective of these conditions, the daily decrease of WMT score was, with one exception, significant (p≤.05).After a 29-hr storage period, there was no significant (p≤.05) difference between three storage and testing conditions. For samples stored longer than 29 hr, best results were obtained with those refrigerated until shortly before testing, when they were equilibrated to room temperature (about 25C), then tested with the reagent, also at room temperature. This method of storing and testing resulted in a significantly (p≤.05) slower decrease in WMT score with increasing age of milk than did the two other methods evaluated.