The effect of age at calving on reproduction, milk production and disease incidence in the first lactation of dairy heifers

Herd health and production records of 1161 Holstein-Friesian heifers from 22 Michigan dairy herds were utilized to study the effect of age at first calving upon reproductive efficiency, milk production and the incidence of disease in the first lactation. Age at first calving was not significantly related to either milk production or reproductive efficiency. Heifers displaying dystocia were significantly older at calving than those that calved without problems. Additionally, the incidence of ketosis was associated with a significantly greater age at first calving. Heifers with diarrhea and those that aborted were significantly younger at calving than their herdmates. Incidence of 12 other common dairy diseases was not related to age at first calving. It would, therefore, appear that the dairy producers we studied could inseminate their heifers at an earlier age, and thereby increase production per day of life, without suffering serious detrimental effects in lactational milk production, reproductive efficiency or overall disease incidence.

Lactose: A definitive guide to polymorph determination

Lactose is a well-known molecule capable of forming a number of different polymorphs with varied chemical and physical properties. To date, no definitive guide for distinguishing between polymorphs using simple analytical techniques has been available. The information presented in this article aims to provide a conclusive guide for identifying the polymorphs of lactose and to successfully unravel years of contradictory research. Data have been collected on single phase polymorphs, prepared from an identical source, adopting the use of in situ and ex situ powder X-ray diffraction, CCD-Raman, FT-IR and (13)C-(1)H cross-polarisation magic angle spinning NMR (CP-MASNMR) spectroscopy, in order to provide simple methods to discriminate between the polymorphs.

Association of Minimum Inhibitory Concentration Cluster Patterns with Dairy Management Practices for Environmental Bacteria Isolated from Bulk Tank Milk

Environmental bacteria have emerged over the past few years to become significant causes of mastitis. Bacteria in this group are often reported by practicing veterinarians to be increasingly resistant to intramammary therapy and responsible for elevated bulk tank somatic cell counts. The purpose of this study was to determine the extent of association of the minimum inhibitory concentrations for selected antimicrobial agents with environmental bacteria isolated from bulk tank milk on California dairies and their housing facilities, husbandry practices, and antimicrobic-use strategies. Bulk tank milk samples were collected from 2 dairy cooperatives that had their milk cultured at the Milk Quality Laboratory, University of California Davis, Veterinary Medicine Teaching and Research Center in Tulare, CA. Samples were collected from July 2001 through March 2002 on 88 d; and 404 environmental bacteria isolated from 93 dairies were found. Minimum inhibitory concentrations were determined on 337 of the isolates for 10 antimicrobial agents. Cluster analysis was performed on the minimum inhibitory concentration values for each organism, and 4 antimicrobial clusters with varying degrees of resistance were found.A 69-question survey questionnaire was completed on-farm for 49 of the 73 dairies that had at least 3 environmental bacterial isolates. The questionnaire sought information on housing facilities, milking management, mastitis prevention, antimicrobial usage strategies, and owner/veterinary involvement in disease control and prevention. Multinomial logistic regression analysis found significant associations between the antimicrobial agent-resistance cluster groups and some of the housing and bedding practices, failure to dry udders before milking, and antimicrobial treatment of nonmastitis conditions. No association was noted for antimicrobial agent treatment of mastitis and the resistance cluster patterns.

Mycoplasma Mastitis: A Review of Transmission and Control

The Mycoplasma sp. that cause mastitis are simple, cell wall-less, bacteria that can colonize and cause diseases in other extramammary sites in the bovine. Prevalence of mycoplasma mastitis appears to be increasing in many locations throughout the world. The best method to identify this group of pathogens is through direct culture on mycoplasma agar media. However, limitations with this culture procedure are the duration of culture, 10 days, special conditions required and thus added expense, and the lack of primary specificity to distinguish between true pathogens and commensal organisms. Thus culture of bulk tank milk samples has been advocated as a primary screening method to determine the mycoplasma status of a herd. This monitoring system is reasonably successful but the sensitivity of detection of Mycoplasma sp. in bulk tank milk is affected by a significant minority of cows that might shed the organism at levels below the threshold of detection. Contagious mastitis control procedures have been effective in controlling outbreaks of mycoplasma mastitis. Yet new methods of control might be warranted, methods that may prevent the outbreak. Current data suggests that a significant number of new outbreaks may occur via internal or animal-to-animal transmission of mycoplasma mastitis pathogens from asymptomatic carriers.

Effect of timing of first clinical mastitis occurrence on lactational and reproductive performance of Holstein dairy cows

Objectives of this study were to determine the influence of timing of first clinical mastitis case occurrence on lactational and reproductive performance in high producing lactating dairy cows during the first 320 days in milk (DIM). Holstein cows, 1001, from two commercial dairy farms in California were retrospectively divided into four treatment groups according to timing of first clinical mastitis case caused by environmental pathogens: control with no recorded clinical cases of mastitis (C; n=501); first clinical mastitis prior to first postpartum AI (MG1; n=250); first clinical mastitis between first postpartum AI and pregnancy diagnosis (MG2; n=147); and first clinical mastitis after diagnosed pregnant (MG3; n=103). Clinical cases of mastitis were identified at every milking by the herd personnel based on abnormal milk or swelling of the mammary gland. A fore sample of milk was aseptically collected from every clinical case for microbiological culture. Mastitis decreased yields of milk, 3.5% fat-corrected milk, and milk components, but the effect was only observed for MG1 and MG2. Cows in the control group had lower linear somatic cell count (SCC) score throughout the lactation. Culling was increased by mastitis, and cows in the mastitis groups left the study earlier than controls. Conception rate at first postpartum AI and pregnancy rate at the end of the study were both decreased by mastitis prior to or after first AI, and MG1 and MG2 cows had extended days open. Furthermore, cows experiencing mastitis during lactation had a higher incidence of abortions. The negative effects of mastitis on reproduction were observed regardless of clinical case being caused by either Gram positive or negative bacteria. Mastitis either prior to or after first postpartum AI impairs lactation performance, increases culling, and decreases reproductive efficiency in high producing Holstein dairy cows.

DairyBeef: Maximizing Quality and Profits—A Consistent Food Safety Message

To respond to meat safety and quality issues in dairy market cattle, a collaborative project team for 7 western states was established to develop educational resources providing a consistent meat safety and quality message to dairy producers, farm advisors, and veterinarians. The team produced an educational website and CD-ROM course that included videos, narrated slide sets, and on-farm tools. The objectives of this course were: 1) to help producers and their advisors understand market cattle food safety and quality issues, 2) help maintain markets for these cows, and 3) help producers identify ways to improve the quality of dairy cattle going to slaughter. DairyBeef. Maximizing Quality & Profits consists of 6 sections, including 4 core segments. Successful completion of quizzes following each core segment is required for participants to receive a certificate of completion. A formative evaluation of the program revealed the necessity for minor content and technological changes with the web-based course. All evaluators considered the materials relevant to dairy producers. After editing, course availability was enabled in February, 2003. Between February and May, 2003, 21 individuals received certificates of completion.

Summary of latent effects in long term survivors of whole body irradiations in primates

The USAF School of Aerospace Medicine, Radiobiology Division, Brooks Air Force Base, Texas presently is maintaining a colony of over 450 primates in which the whole body has been exposed to various types of space radiation including protons and electrons. The majority of the primates (Macaca mulatta) were exposed during 1965. Types of radiation involved are 2 MeV X-rays, 5 MeV-2.3 GeV protons and 1.6 MeV electrons. Low energy proton dose range up to 3000 rad (50-100 rad min-1) whereas the penetrating energy doses range up to 700 rad (15-100 rad min-1). Primates from a simulated solar flare exposure are also included. In late 1970, a small group of primates exposed to 108 and 85 MeV alpha particles (eye and partial body only) were added to the colony. Data are available in the following areas: (i) chronic skin changes; (ii) testicular atrophy; (iii) cataractogenesis; (iv) hematological and serum biochemical analysis; (v) incidence of tumors; (vi) causes of death; (vii) body weight variations; and (viii) summary of alpha particle experiences.

Effect of a commercially available nonspecific immunomodulating biologic product on health of neonatal calves

OBJECTIVE

To determine whether treatment with a commercially available nonspecific immunomodulating biologic product would alter the clinical course of disease in neonatal calves.

DESIGN

Systematically randomized, controlled cohort study.

ANIMALS

200 Holstein bull calves 1 to 5 days old.

PROCEDURE

Assessments were performed that included evaluation of fecal consistency, attitude, appetite, and hydration status. Calves with abnormal results were enrolled in the study. Calves were systematically assigned to control or treatment groups (100 calves/group). Calves in the treatment group were given a single i.v. injection of the biologic product at the time of enrollment, whereas control calves were not given the product. Calves were assessed daily for 5 days to evaluate fecal consistency, attitude, appetite, hydration status, and rectal temperature. Assessments were made without knowledge of group assignment.

RESULTS

Treatment with the immunomodulating product was not associated with a decrease in the number of calves that had moderate or severe departures from clinically normal conditions for attitude, appetite, or hydration on days 1 though 5, compared with control calves. Fecal consistency scores were significantly greater for treated calves on days 1 (P = 0.03) and 5 (P = 0.02), compared with scores for control calves.

CLINICAL IMPLICATIONS

Administration of the nonspecific immunomodulating biologic product did not significantly affect outcome of clinical disease for calves in the treated group, compared with calves in the control group. On the basis of results of this study, we cannot recommend use of the nonspecific immunomodulating biologic product for the treatment of undifferentiated diarrheal disease in neonatal calves.

Research notes: Prevalence of selected microbial pathogens in processed poultry waste used as dairy cattle feed

Processed poultry litter intended for dairy cattle feed was collected on 13 dairy ranches in the San Joaquin Valley of California and analyzed for the presence of significant bacterial pathogens associated with clinical disease in cattle or foodborne disease in humans. Litter samples were collected from the surface and interior of the litter piles upon arrival on the dairies and 2 to 4 wk later. Litter samples were cultured for Salmonella, Escherichia coli, Campylobacter, and other bacteria. The temperature of the litter piles was obtained on the surface and interior at each sampling. Dry matter was determined for each sample. No Salmonella, E. coli O157, or Campylobacter was identified (n = 104). Other E. coli strains were found in 8 out of 52 samples on arrival and 4 out of 52 samples at 2 to 4 wk after arrival. Although the surface and interior temperatures of the litter pile were different (23 C vs 50 C, respectively), the mean temperatures did not significantly change with time on the ranches. Average dry matter content did not differ between samples. In conclusion, the pathogens under investigation were not detected in processed poultry litter on these California dairy ranches upon arrival at the dairy or 2 to 4 wk later.

Epidemiologic analysis of Mycoplasma spp isolated from bulk-tank milk samples obtained from dairy herds that were members of a milk cooperative

OBJECTIVE

To determine the prevalence of Mycoplasma spp in herds that were members of a milk cooperative.

DESIGN

Epidemiologic study.

SAMPLE POPULATION

267 dairy herds that were members of a milk cooperative.

PROCEDURE

Bulk-tank milk samples were collected monthly during a 6-year period from all dairies in the cooperative. Samples were submitted to the cooperative's laboratory for bacterial culture for Mycoplasma spp, using direct plating. Milk samples positive for Mycoplasma organisms were speciated.

RESULTS

Prevalence of positive samples varied from 1.8 to 5.8% for all species of Mycoplasma and from 1.2 to 3.1% for Mycoplasma spp known to be mastitis pathogens. One mycoplasmal species was isolated initially on 99 of 198 (50.0%) dairies, but 68 of 198 (34.3%) dairies had 2 species isolated. Mycoplasma bovis, M californicum, and M bovigenitalium were consistently isolated, but M bovis (243/499; 48.6%) was the most commonly isolated species. Acholeplasma laidlawii was more prevalent in 1989 and 1995 than other years. Mycoplasma bovigenitalium and M californicum had a seasonal distribution. Less than 50 colonies per plate were isolated for most (317/500; 63.4%) bulk-tank samples. Of the milk samples with > 100 colonies/plate, Mycoplasma bovis was isolated most frequently (73/243; 30.0%).

CLINICAL IMPLICATIONS

Distribution of Mycoplasma spp varied by year, number of colonies isolated per sample, season, and herd. Therefore, it may be necessary to routinely sample bulk-tank milk, and all isolates should be speciated. Culture results from milk cooperatives should be used with other monitoring information to determine the Mycoplasma status of herds.

Effects of antimicrobial treatment at the end of lactation on milk yield, somatic cell count, and incidence of clinical mastitis during the subsequent lactation in a dairy herd with a low prevalence of contagious mastitis

OBJECTIVE

To determine whether treating cows with antimicrobials at the end of lactation would lower the incidence of clinical mastitis, improve milk production, and decrease somatic cell count (SCC) in the subsequent lactation.

DESIGN

Randomized blind field trial.

ANIMALS

233 Holstein cows from a single herd. All cows were in lactation 2 or greater.

PROCEDURE

Cows were randomly assigned to treatment groups. Treated cows were given procaine penicillin G and novobiocin by intramammary infusion. Control cows were not treated. Farm personnel recorded cases of clinical mastitis. Milk yield and SCC were recorded during the subsequent lactation.

RESULTS

Treatment did not significantly reduce the incidence of clinical mastitis when data for all cows were grouped or when data were stratified by lactation groups (lactation 2 vs lactation > or = 3) or by last SCC (< or = 500,000 cells/ml vs > 500,000 cells/ml). Somatic cell counts (first, mean of first 5, maximum of first 5) for treated and control cows were similar, and proportions of treated and control cows with SCC > 500,000 cells/ml at least once were not significantly different. Treated cows produced 179 kg (394 lb) more milk during the first 17 weeks of lactation than did control cows.

CLINICAL IMPLICATIONS

Treating cows with antimicrobials at the end of lactation increased 17-week milk production during the subsequent lactation and, at current milk prices, was financially preferable to not treating them.

Sensitivity and specificity analysis for somatic cell count (SCC) used to predict bacteriologically positive subclinical mastitis at calving in a dairy herd with low SCC

OBJECTIVE

Validate, by sensitivity and specificity analyses, use of somatic cell count (SCC) to predict bacteriologically positive subclinical mastitis in a California dairy herd with low SCC.

DESIGN

Study of monthly dairy herd improvement SCC obtained from the immediate preceding lactation and individual cow composite milk sample microbiologic isolates collected at calving.

ANIMALS

515 California dairy cows with SCC and culture data.

PROCEDURE

Somatic cell count sensitivity and specificity analyses with combinations of SCC parameter and at various thresholds were done, using the bacterial isolates as the standard.

RESULTS

Combination of SCC threshold and SCC parameters could not be developed that had sufficient sensitivity and specificity to be a useful predictor of cows that would calve with subclinical mastitis.

CLINICAL IMPLICATIONS

Under the conditions at this particular dairy, SCC could not be used as a basis of prediction of cows that would calve with bacteriologically positive subclinical mastitis or require selective nonlactating-cow antibiotic treatment.

Comparison of maternal blood and fetal liver selenium concentrations in cattle in California

Selenium concentration was measured in paired maternal blood samples and fetal liver specimens collected at a San Joaquin County, Calif, slaughterhouse (beef = 19, dairy = 54) and from bovine aborted fetuses submitted to the California Veterinary Diagnostic Laboratory System (CVDLS; beef = 20, dairy = 20). Of the slaughterhouse samples and specimens, dairy maternal blood selenium concentration was significantly (P < 0.001) higher (mean +/- SD; 0.22 +/- 0.056 microgram/ml) than that for beef breeds (0.137 +/- 0.082 microgram/ml). The CVDLS mean maternal blood selenium concentration for the dairy-breed samples (0.192 +/- 0.028 microgram/ml) was similar to that for the slaughterhouse dairy-breed samples, but was greater than that for the slaughterhouse beef-breed samples. Slaughterhouse mean fetal liver selenium content also was higher (P < 0.001) for the dairy breeds (0.777 +/- 0.408 microgram/g), compared with the beef breeds (0.443 +/- 0.038 microgram/g). Mean fetal liver selenium content for slaughterhouse specimens was higher (P < 0.002) than that for the CVDLS specimens (beef, 0.244 +/- 0.149 microgram/g; dairy, 0.390 +/- 0.165 microgram/g). At the CVDLS, dairy fetal liver content was greater (P < 0.001) than that for beef breeds. Mean ratio of fetal liver selenium content to maternal blood selenium concentration was 3.53 +/- 1.89 for dairy breeds at the slaughterhouse (liver-to-blood correlation [r] = 0.38), and was 2.11 +/- 1.00 for dairy breeds at the CVDLS (r = 0.31) and 3.43 +/- 1.50 for beef breeds (r = 0.58). Both slaughterhouse breed ratios were significantly (P < 0.002) greater than the CVDLS dairy-breed ratio. On the basis of these results, breed and source location should be taken into account when interpreting selenium values. Fetal liver selenium content should only be used as a screening test and combined with whole blood selenium concentration from clinically normal herdmates to evaluate herd selenium status.

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.

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.

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).

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.

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.

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.

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.

Repeated insemination in Michigan Holstein-Friesian cattle: Incidence, descriptive epidemiology and estimated economic impact

Twenty-two Michigan dairy herds participating in a computerized herd-health program were studied to determine the incidence and epidemiologic characteristics of repeat-breeder syndrome. A cow with repeat-breeder syndrome was defined as having been inseminated three or more times within the same lactation. Repeat-breeder syndrome was observed in 24% of 3,309 lactations. Cost components associated with unsuccessful inseminations included costs of delayed conception, extra inseminations, extra veterinary service and losses due to culling. Lactations with repeat-breeder syndrome were associated with a loss of approximately $385. An estimated extra cost of $140 was associated with a second insemination, $279 with three inseminations, $429 with four inseminations and $612 with five inseminations.

Factors associated with neonatal lamb mortality

Three factors were associated with lamb neonatal mortality: birthweight (P<0.003), number of lambs born per ewe (P<0.001) and lamb sex (P<0.32). Lamb birthweight had the greatest predictive power for survival during the neonatal period. The neonatal mortality rate was 14.3%. The age specific mortality for lambs one day old was 7.9% (P<0.05). Seventy-nine percent of the lambs that died, did so by the end of the fourth post-natal day. Starvation was associated with 58.3% (P < 0.05) of the lamb deaths.

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.

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.

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.

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.

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.

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.

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).

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.

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.

Effects of feeding cull domestic onions (Allium cepa) to sheep

Twenty crossbred Panama yearling ewes were used to determine the effects of feeding cull onions (Allium cepa) to sheep. Ten test ewes were fed onions free choice with supplemntal alfalfa hay and grain, whereas ten control ewes were fed only alfalfa hay and grain. Anemia developed within 3 weeks in the test ewes, but was not seen in the controls. All ewes remained clinically normal during the study. Onions were fed for about 130 days. Recovery of the erythrocyte system began before the end of the feeding period. Even though onions were fed during most of the gestation period, the numbers of lambs born in the test and control groups were essentially the same.

Endometriosis in four irradiated rhesus monkeys

Four Rhesus monkeys that had been irradiated at 1 year of age and developed extensive endometriosis of the pelvic and peritoneal cavities 7 years later. Endometriosis was characterized by aggressive viable nonanaplastic endometrial epithelial cells in ectopic sites throughout the genital organs. Theories of pathogenesis for man may not be valid for nonhuman primates. Retrograde flow of endometrial fragments via the oviducts may be the source of the extrauterine lesions since in monkeys 1, 2, and 4 the ovaries were in the main extrauterine masses. Whether the extrauterine endometrium is metaplastic or metastatic, there is little doubt that endometriosis is linked to the cyclic hormones of the female's reproductive cycle. The cases reported occurred at 8 years of age, and the deaths may illustrate shortening of life as a latent effect of irradiation.

Hartmannellosis in a bull

A case of Hartmannella sp. (Acanthamoeba) infection in a 1 1/2-year-old Holstein bull is reported. The disease was manifested by multifocal necrohemorrhagic nodules throughout the lung. Diagnosis was made on a morphologic basis by observing typical organisms within these nodules. The suggested mode of entry of the organism was via inhalation of the organisms or by direct extension from an inapparent nasal infection.