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Biomedical subjects

J H Kirk

Publications and source records attributed to J H Kirk.

At least 19 recordsLinked to original sources
PubMed1994

Milk production in cows with endotoxin-induced mastitis treated with isotonic or hypertonic sodium chloride solution.

Milk production was monitored in 16 cows for 6 milkings after intramammary infusion of 1 mg of endotoxin in a single forequarter. The cows were randomly assigned to 1 of 2 treatment groups; 8 cows were treated with isotonic saline solution and 8 cows were treated with hypertonic saline solution. Saline solutions were administered IV (5 ml/kg of body weight) 4 hours after infusion of endotoxin. Mean cumulative change in milk yield and interval change in milk yield were greater in cows treated with isotonic saline solution than in cows treated with hypertonic saline solution. Significant differences between treatment groups were not detected.

Animals↗
PubMed1993

Advances in the therapy for mastitis.

Methods to enhance mammary resistance to bacterial infection and to reduce the effects of existing infections without the use of antimicrobial agents are becoming more attractive, primarily because of increasing pressure from consumers and regulatory agencies to decrease the risk of drug residues in milk. Because of the difficulty in obtaining satisfactory results with existing drug formulations, new approaches in the treatment of mastitis should emphasize better understanding of mammary gland pharmacokinetics, ameliorating the pathologic effects of infection, and enhancing natural defenses. Efficacy studies should emphasize milk production and long-term survival of cows to allow economic evaluations.

Acute Disease↗
PubMed1991

N-acetyl-beta-D-glucosaminidase as a predictor of milk loss and recovery after clinical mastitis.

Milk samples were collected at onset of 508 episodes of clinical mastitis on a 1,700-cow dairy farm in Michigan. Daily milk production and disease events were recorded for all cows in the herd. Despite statistical association with severity of mastitis, this association was too weak for N-acetyl-beta-D-glucosaminidase (NAGase) activity to be of great value as a prognostic test for clinical mastitis. High milk NAGase activity was significantly (P less than 0.0001) associated with: increased duration of treatment; increased duration of clinical signs of mastitis; decreased daily milk production; and increased risk of the cow being culled because of mastitis. The NAGase value was combined with days in milk production, baseline milk production before mastitis onset, parity, and season of onset to predict the outcome of clinical cases as measured by the first 3 aforementioned variables. Statistical models explained little of the variability among cows in duration of treatment (R2 = 0.11), duration of clinical signs of infection (R2 = 0.11), and milk production change (R2 = 0.09).

Acetylglucosaminidase↗
PubMed1990

Serratia marcescens mastitis in a dairy herd.

Serratia marcescens caused clinical mastitis in 5 cows and nonclinical mastitis in 21 cows of a 190-cow herd. Repeated bacteriologic culture of specimens from the cows, postmilking teat dip, environment, and equipment was performed. Serratia marcescens was not isolated from the dip, environment, or equipment. Progress of the infection in cows was monitored for 10 months. Some cows remained infected with S marcescens for at least 10 months. Economic loss estimates were based on Dairy Herd Improvement Association linear score reports. The average nonclinical loss was about $22/cow.

Animals↗
PubMed1990

Milk production and somatic cell count in Michigan dairy herds.

The established association between milk production and SCC in dairy cattle is increasingly used to estimate lost production due to mastitis. Such cost estimates are used to make decisions regarding cost effective mastitis prevention and control. It is therefore important to verify the relationship between SCC and milk production using data from different areas of the country and by using different analytical methodology. Our study used the 1985 to 1986 Michigan DHIA data base and analyzed daily milk production records rather than lactation summary records as used in the past. One advantage to our approach was that it did not give equal weight to all lactations, regardless of their duration. Also, it enabled inclusion of cows that had incomplete lactations caused by culling, or had other reasons for removal from the herd. A statistical model was constructed to predict milk production on the basis of herd, cow within herd, stage in lactation, month of calving, lactation, and SCC. The data base contained 397,172 milk test records obtained from Michigan DHIA from 504 Holstein herds in Michigan's lower peninsula. Our final model predicted 78% of the variation in milk production. Prediction of milk loss for each herd was highly correlated (r = .98) with the prediction model adopted by most DHIA organizations. Our model predicted that the mean herd lost a mean of 1.17 kg of milk/cow per d associated with SCC.

Age Factors↗
PubMed1989

Cost of mastitis and its prevention in four dairy cattle herds on St Croix, US Virgin Islands.

Nonclinical mastitis in the dairy herds on St Croix, US Virgin Islands, represents a prevalent (97%) and severe problem (44% of quarters had California Mastitis Test results of 2 or 3). Streptococcus agalactiae (26%) and Staphylococcus aureus (22%) were the most prevalent pathogens. More than half (54%) of all organisms isolated and tested for resistance were resistant to ampicillin and benzyl penicillin; 29% were resistant to trimethoprim/sulfadiazine. Estimates of the loss of milk production suggested that there was a loss of 4.40 to 13.33 lb/cow/day. The yearly economic cost of prevention was estimated for each cow ($22.07); yearly income loss attributable to mastitis was estimated to be from $339 to $1,022/cow/yr. Suggestions for the prevention and control of mastitis are included.

Animals↗
PubMed1989

Failure to detect antibody to bovine respiratory syncytial virus in bovine fetal serum.

Sera obtained from 147 bovine fetuses estimated to be between 120 and 270 days of gestation at an abattoir were tested for antibody to bovine respiratory syncytial virus. Antibody to bovine respiratory syncytial virus was not detected in any of the sera examined. Based on the results of this study and a review of the literature, it appears that transplacental infection by bovine respiratory syncytial virus does not occur, or is uncommon.

Animals↗
PubMed1984

Stray voltage on Michigan dairy farms.

Stray voltage investigations were performed on 59 Michigan dairy farms at the request of dairymen, veterinarians, and county extension agents. On 32 farms, sources of stray voltage were detected. When the voltage exceeded 1 volt alternating current, there were increased numbers of dairy cows that had abnormal behavior in the milking facility and increased prevalence of clinical mastitis. Recovery from the stray voltage-induced abnormalities was related to the type of abnormality and the magnitude of the exposure voltage.

Animals↗
PubMed1984

Nonclinical Pseudomonas aeruginosa mastitis in a dairy herd.

Atypical Pseudomonas aeruginosa mastitis in a dairy herd was characterized by nonclinical mastitis that responded to antibiotic treatment, but only for the cows to become reinfected because of a persisting source of contamination in the milking parlor wash water. At least 36% of the cows were infected during a 37-month period. The source of infection was contaminated water, wash hoses, and spray nozzles in the parlor. After the source of infection was removed and long-term control measures were instituted, the nonclinical infections became less severe and shorter in duration and they occurred for a lesser percentage of the lactation period.

Animals↗
PubMed1984

Programmable calculator program for linear somatic cell scores to estimate mastitis yield losses.

A programmable calculator program calculates loss of milk yield in dairy cows based on linear somatic cell count scores. The program displays the distribution of the herd by lactation number and linear score for present and optimal goal situations. Loss of yield is in pounds and dollars by cow and herd. The program estimates optimal milk production and numbers of fewer cows at the goal for mastitis infection.

Animals↗
PubMed1982

Bovine cystic ovarian disease: hereditary relationships and case study.

Cystic ovarian disease (COD) was studied in a closed 300-cow dairy herd, using Dairy Herd Improvement Association and individual health records for a 7-year period (1974-1980). There were 2,112 calvings by 649 cows during the period. Cysts were found in 130 cows. Of the 649 cows that calved, 110 (16.9%) produced at least 1 daughter in which COD developed. Two bulls sired 17.6% of the daughters with COD, which was more than anticipated inasmuch as they sired only 11.6% of all daughters (P less than 0.05). These bulls were removed from the breeding program in an attempt to reduce code in the herd.

Animals↗
PubMed1982

Border disease virus isolation from postpartum ewes.

The prevalence of border disease virus in a flock of Targhee sheep in southern Idaho was determined by serologic and virologic techniques. Of 249 ewes, 73 (29%) were seropositive to the antigenically related togavirus, bovine seropositive to the antigenically related togavirus, bovine viral diarrhea virus (BVDV). Concurrent testing of sera from 337 neonatal lambs indicated that 172 (51%) were seropositive for BVDV. It was observed that a high percentage (35%) of the BVDV-seropositive lambs were derived from seronegative ewes. Immunotolerance of the ewe was considered as the explanation for the lack of serologic relationship between seropositive lambs and their seronegative dams. Eleven cytopathogenic viruses were isolated from nasal and vaginal specimens obtained from 80 clinically healthy ewes within 24 hours of parturition. The viral isolates were demonstrated to be antigenically related to BVDV by direct immunofluorescence. Six of the 11 isolates were obtained from BVDV-seronegative ewes.

Animals↗
PubMed1981

Relationship of neonatal mortality in lambs to serologic status of the ewe for Toxoplasma gondii.

The indirect hemagglutination method was used to determine the seroprevalence of Toxoplasma gondii in a random sample (250) of lambing ewes from a large (4,226 ewes) western range flock. Agglutination (greater than or equal to 2+) at the 1:64 serum dilution was considered a positive reaction; the seroprevalence was 20.8%. The neonatal mortality for lambs born to seropositive ewes was 30.7%, which was significantly greater than that for seronegative ewes (13.6%). The average age at death for lambs born to seropositive ewes was 24.8 hours, which was significantly less than that for lambs born to seronegative ewes (31.2 hours).

Animals↗
PubMed1981

Serologic prevalence of ovine progressive pneumonia in a western range flock of sheep.

Of 254 sheep examined for antibodies to the virus of ovine progressive pneumonia, 162 (63.8%) were seropositive. The mean age of the seropositive ewes was 4.9 +/- 1.8 years, which was significantly greater than that for the seronegative ewes (4.1 +/- 2.3 years). The age-specific prevalence increased with ewe age, from 25% among yearling ewes to 85% among 7-year-old ewes. Seropositive ewes produced more pounds of live lamb at birth than did seronegative ewes.

Animals↗
PubMed1981

Application of programmable calculators to Mastitis control programs.

Three programs pertaining to subclinical mastitis losses and control are described for use in handheld programmable calculators. Subclinical mastitis losses are calculated on the basis of lost milk estimates for California Mastitis Test evaluations. A cost profile for control programs using costs of single use towels, teat dips, and dry cow treatment is described. The cost-benefit value of a mass lactating cow antibiotic treatment regimen is presented. The programs quickly calculate the magnitude of the present subclinical mastitis loss, estimate the cost of control programs, and present information to aid in deciding whether to treat all the infected cows during lactation in an effort to reduce herd infection. User instructions and program listings are included.

Animals↗
PubMed1980

Mastitis and udder abnormalities as related to neonatal lamb mortality in shed-lambed range ewes.

Bacterial isolations were attempted from milk samples taken from 242 range ewes in a southwestern Idaho shed lambing enterprise. Eighty-five percent of the ewe milk samples had no pathogenic bacterial growth at lambing and 3 weeks later. The few organisms that were isolated did not appear to affect udder condition of the ewe or contribute to lamb mortality. Shed conditions did not affect the frequency of isolation of potentially pathogenic bacteria. The prevalence of udder abnormalities, however, did appear to have a positive association with ewes that lost theim lambs. The most frequent abnormality was a diffuse homogeneous induration of the udder. This hardening was apparently unrelated to bacterial isolation or the age of the ewes. Mastitis, either subclinical or clinical, did not appear to be a serious problem in this particular flock. Mastitis was not related to lamb mortality.

Animals↗