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SUMMARY

In an effort to characterize the activity of serum γ-glutamyltransferase (ggt) in newborn calves before and after suckling and to explore the usefulness of serum ggt as an indicator of failure of passive transfer in calves, blood samples were collected from the first calves of 48 cows at the time of birth and at 1 day of age. Serum was harvested, and concentrations of IgG and protein and activity of ggt were determined. Morbidity and mortality events were monitored from birth to weaning. Calves suckling colostrum had 10 and 1.3 times greater serum concentrations of IgG and protein, respectively, and a 26 times greater serum activity of ggt, compared with concentrations at birth. Increases in ggt activity and protein concentration were correlated to increases in IgG concentration. Calves classified as having failure of passive transfer (< 800 mg of IgG/dl) had a 9.5 times greater risk of becoming sick prior to weaning, compared with calves determined to have partial failure of passive transfer and clinically normal calves (P= 0.0004). The sensitivity and specificity of a cutoff value of 200 IU of ggt/L of serum for diagnosing failure of passive transfer were 80 and 97%, respectively. The sensitivity and specificity of a cutoff value of 4.2 g of protein/dl of serum for diagnosing failure of passive transfer were 80 and 100%, respectively. The Kappa values for diagnosis of failure of passive transfer, using serum concentrations of IgG vs activity of ggt, IgG vs protein, and ggt vs protein, were 0.72, 0.86, and 0.79, respectively. The value of using ggt activities for diagnosis of hepatic lesions is limited during at least the first week of life in calves that consume adequate amounts of colostrum. The most cost-effective and rapid indicator of passive immune status in this study was determination of serum total protein. Serum activity of ggt also gave reliable indications of passive immune status. Procedures used to determine these values were less expensive and gave results sooner than single radial immunodiffusion for IgG.

Free access
in American Journal of Veterinary Research

SUMMARY

A successful attempt was made to mechanically transmit bovine leukosis virus (blv) from a blv-infected cow with a normal lymphocyte count to sheep by inoculation with horse fly (Tabanus abactor) mouthparts. After interrupted natural feeding, horse flies were anesthetized with CO2. Mouthparts were severed and pooled into a tissue grinder containing medium. Five inocula containing the mouthparts of 10 flies each, and 5 inocula containing the mouthparts of 20 flies each, were prepared and inoculated sc in the right axilla of 10 blv antibody-negative sheep. Five additional sheep served as controls. Serum samples were collected at 2-week intervals and tested by agar gel immunodiffusion for blv antibodies.

One sheep injected with 20 mouthparts developed antibodies to blv at 10 weeks after inoculation. Six months after inoculation with fly mouthparts, 1 blv antibody-negative sheep was randomly selected from each treatment group and injected, in the left axilla, with 3 ml of blood from the donor cow to confirm susceptibility of the sheep. All 3 sheep developed antibodies to blv within 4 weeks.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effects of florfenicol injection on the meat characteristics of the cervical muscles in cattle.

Animals—100 steers (mean weight, 380 kg).

Procedure—In 50 calves, florfenicol (25 ml, twice) was injected into the cervical muscles of 1 side of the neck, and saline (0.9% NaCl) solution (25 ml, twice) was injected into the cervical muscles of the other side of the neck. In the remaining 50 calves, florfenicol was injected into the cervical muscles of 1 side of the neck, and nothing was injected into the cervical muscles of the other side of the neck. Animals were slaughtered 132 days later, and samples of the cervical muscles were submitted for histologic evaluation and measurement of shear forces.

Results—2 injection sites used in the present study had extensive lesions, and both of these were sites where florfenicol had been injected. However, histologic scores for the florfenicol injection sites were not significantly different from scores for the contralateral saline solution injection sites and uninjected control sites. In addition, shear force values were not significantly different between sites in which florfenicol had been injected and the contralateral sites.

Conclusion and Clinical Relevance—Results suggest that few reactions should be expected with injection of florfenicol into the cervical muscles in steers and that reactions that do occur will consist mainly of fibrosis and infiltration of adipose tissue. However, shear force values, a measure of tenderness of the meat, should not be affected. (Am J Vet Res 2002;63:64–68)

Full access
in American Journal of Veterinary Research

Objective

To quantify the effects of treatment for clinical respiratory tract disease and pulmonary lesions identified at slaughter on rate of weight gain in feedlot cattle.

Design

Prospective longitudinal study

Animals

469 feedlot steers.

Procedure

Clinical respiratory tract disease was monitored between birth and slaughter. Steers were weaned at approximately 6 months old and entered into the feedlot for a mean of 273 days. Mean daily weight gain (MDG) was monitored during the feeding period. Lungs were collected at slaughter and evaluated for gross lesions indicative of active or resolved pneumonia.

Results

Mean daily weight gain during the feeding period was 1.30 kg, and ranged from 1.16 to 1.46 kg within individual pens. Thirty-five percent of steers received treatment for respiratory tract disease between birth and slaughter, whereas 72% had pulmonary lesions evident at slaughter. Among steers treated for clinical respiratory tract disease, 78% had pulmonary lesions, whereas 68% of untreated steers had pulmonary lesions. Pulmonary lesions at slaughter were associated (P < 0.01) with a 0.076-kg reduction in MDG during the feeding period. Treatment for clinical disease was not associated with MDG after adjustment for the effect of pulmonary lesions.

Clinical Implications

Treatment of clinically affected feedlot cattle may be inadequate to prevent significant production losses attributable to respiratory tract disease. (J Am Vet Med Assoc 1996;209:814-818)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To quantify haptoglobin response to respiratory tract disease in feedlot cattle, and to investigate its ability to predict disease outcome and response to antibiotic treatment.

Design

Randomized clinical trial.

Animals

60 feedlot calves with clinical respiratory tract disease.

Procedure

Calves were randomly assigned to receive a standard antibiotic treatment regimen (TRT), or to observation pens without antibiotic treatment. Serum haptoglobin concentration was measured at initial and final examinations. Calves were examined for presence of gross pulmonary lesions at slaughter.

Results

Mean ± SD serum haptoglobin concentration at initial examination was 67 ± 108 mg/dl, with range of 0 to 508 mg/dl. Haptoglobin concentration at initial examination was similar for the TRT group and the group that did not receive antibiotic treatment, but at final examination, TRT-group calves had lower (P < 0.01) mean values. Calves receiving antibiotic treatment had haptoglobin concentration at or near zero at final examination. Calves not receiving antibiotic treatment had only slightly lower mean haptoglobin concentration at final examination, compared with initial examination. Within treatment groups, haptoglobin concentration was similar for cases with different outcomes. Calves with gross pulmonary lesions a: slaughter had numerically higher, although statistically similar, haptoglobin concentrations at initial examination, compared with calves without lesions.

Conclusions

Feedlot cattle with clinical respiratory tract disease have a large and variable haptoglobin response. Antibiotic treatment resulted in lower serum haptoglobin values, although low values were not required for full clinical recovery.

Clinical Relevance

Serum haptoglobin concentration may be an indicator of response to antibiotic therapy, although it appears to be unrelated to case severity or need for treatment. (Am J Vet Res 1996; 57:646–649)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To determine serum haptoglobin concentrations in a population of feedlot cattle and evaluate their usefulness in predicting subsequent clinical respiratory tract disease.

Design

Prospective longitudinal study.

Animals

366 beef calves.

Procedure

Serum samples were obtained at feedlot entry and 40 and 65 days on feed (DOF). Calves were observed daily for clinical signs of respiratory tract disease. The lungs of 144 of the calves were evaluated at slaughter for the presence of gross lesions of pneumonia.

Results

58% of the calves had detectable serum haptoglobin concentration in at least 1 sample. The proportion of calves with detectable haptoglobin were similar at each sample collection time. A higher proportion of the calves had values > 10 mg/dl at 40 DOF. The prcportion of calves observed with clinical disease during the 10-day period after the 40 DOF sample increased (P < 0.10) as serum haptoglobin concentration increased. At 65 DOF, calves with serum haptoglobin value > 10 mg/dl had a higher (P < 0.05) rate of subsequent clinical respiratory tract disease than did calves with lower values. The proportion of calves with gross pulmonary lesions slaughter increased (P < 0.05) from 39% among calves without detectable serum haptoglobin concentration in any of the 3 samples to 63% among calves with at least 1 observed value > 10 mg/dl.

Conclusions

We observed associations between serum haptoglobin concentration and subsequent clinical respiratory tract disease and pulmonary lesions at slaughter. However, serum haptoglobin concentration alone is not adequate for prediction of clinical disease.

Clinical Relevance

The usefulness for cross-sectional sampling of serum haptoglobin concentration as a diagnostic tool for clinical respiratory tract disease in feedlot cattle appears to be limited.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To investigate eating and drinking behaviors and their association with bovine respiratory disease complex (BRDC) and to evaluate methods of diagnosing BRDC.

Animals—170 newly arrived calves at a feedlot.

Procedure—Eating and drinking behaviors of calves were recorded at a feedlot. Calves with clinical signs of BRDC were removed from their pen and classified retrospectively as sick or not sick on the basis of results of physical and hematologic examinations. Pulmonary lesions of all calves were assessed at slaughter.

Results—Calves that were sick had significantly greater frequency and duration of drinking 4 to 5 days after arrival than calves that were not sick. Sick calves had significantly lower frequency and duration of eating and drinking 11 to 27 days after arrival but had significantly greater frequency of eating 28 to 57 days after arrival than calves that were not sick. Calves at slaughter that had a higher percentage of lung tissue with pneumonic lesions had significantly lower frequency and duration of eating 11 to 27 days after arrival but had significantly higher frequency and duration of eating 28 to 57 days after arrival. Agreement for calves being sick and having severe pulmonary lesions at slaughter was adequate. Agreement for calves being removed and having pulmonary lesions at slaughter was low.

Conclusions and Clinical Relevance—Eating and drinking behaviors were associated with signs of BRDC, but there was not an obvious predictive association between signs of BRDC in calves and eating and drinking behaviors. Fair to poor agreement was observed between antemortem and postmortem disease classification. (Am J Vet Res 2000;61:1163–1168)

Full access
in American Journal of Veterinary Research

Abstract

Objectives—To determine the effect of location for administration of clostridial vaccines on behavior, growth performance, and health of calves at a feedlot, the relative risk of calves developing an injection-site reaction or being misdiagnosed as having bovine respiratory disease complex (BRDC), and the percentage of subcutaneous injection-site reactions that were detectable on carcasses after the hides were removed.

Animal—170 newly arrived calves at a feedlot.

Procedure—Eating and drinking behaviors of calves during the initial 57 days after arrival were observed at a commercial feedlot, using an electronic monitoring system. Calves were assigned randomly to receive a clostridial vaccine (base of ear or neck). Data on reactions at the injection site were collected.

Results—Mean daily gain (MDG) for the initial 57 days did not differ significantly between treatments. Risk of being misdiagnosed as having BRDC was not associated with location for administration of vaccine. Calves vaccinated in the base of the ear were at higher risk of having an injection-site reaction at day 57 or at slaughter. Eighty-nine percent (95% confidence interval, 52 to 100%) of injection-site reactions in the neck could not be located on the carcasses after hides were removed. Calves vaccinated in the neck drank significantly fewer times per day during the first 57 days than calves vaccinated in the base of the ear.

Conclusions and Clinical Relevance—Location for administration of a clostridial vaccine did not significantly affect health, growth performance, or eating behavior. Most subcutaneous injection-site reactions were not detectable after the hide was removed. (Am J Vet Res 2000;61:1169–1172)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To describe patterns of seroconversion to bovine coronavirus (BCV) and shedding of BCV from the respiratory tract in feedlot cattle.

Animals—1,074 calves in feedlots in Ohio, Texas, and Nebraska.

Procedure—Nasal swab specimens were obtained at time of arrival (day 0) and at various times during the initial 28 days after arrival at feedlots. Specimens were tested for BCV, using an antigen-capture ELISA. Serum samples were obtained at time of arrival and again 28 days after arrival; sera were analyzed for antibodies to BCV, using an antibody-detection ELISA.

Results—Samples from 12 groups of cattle entering 7 feedlots during a 3-year period revealed that 78 of 1,074 (7.3%) cattle were shedding BCV (range, 0 to 35.9% within specific groups). At time of arrival, 508 of 814 (62.4%) cattle had low (< 50) or undetectable BCV antibody titers. Seroconversion to BCV during the initial 28 days after arrival was detected in 473 of 814 (58%) cattle tested (range, 20.3 to 84.1% within specific groups). In cattle shedding BCV from the nasal passages, 49 of 68 (72.1%) seroconverted, and 472 of 746 (63.3%) cattle that were not shedding the virus seroconverted.

Conclusions and Clinical Relevance—Bovine coronavirus can be detected in populations of feedlot cattle in the form of viral shedding as well as seroconversion to the virus. Although only a few cattle were shedding the virus at the time of arrival at a feedlot, most of the cattle seroconverted to BCV by 28 days after arrival. (Am J Vet Res 2000;61:1057–1061)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the association between respiratory tract infection with bovine coronavirus (BCV), treatment for respiratory tract disease, pulmonary lesions at slaughter, and average daily gain in cattle in feedlots.

Animals—837 calves in feedlots in Ohio and Texas.

Procedure—Nasal swab specimens were obtained from cattle at arrival in a feedlot (day 0) and at various times during the initial 28 days after arrival. Specimens were tested for BCV, using an antigencapture ELISA. Serum samples were obtained at arrival and again 28 days after arrival and tested for antibodies to BCV, using an antibody-detection ELISA. Information was collected regarding treatment for cattle with respiratory tract disease and average daily gain during the feeding period. Pulmonary lesions were evaluated at slaughter.

Results—Cattle shedding BCV from the nasal cavity and developing an antibody response against BCV were 1.6 times more likely to require treatment for respiratory tract disease than cattle that did not shed the virus or develop an immune response against BCV. Additionally, cattle that shed BCV from the nasal cavity were 2.2 times more likely to have pulmonary lesions at slaughter than cattle that did not shed the virus. The BCV shedding or seroconversion status did not affect average daily gain.

Conclusions and Clinical Relevance—Bovine coronavirus infects feedlot cattle and is associated with an increased risk for cattle developing respiratory tract disease and pulmonary lesions. Development of appropriate control measures could help reduce the incidence of respiratory tract disease. (Am J Vet Res 2000;61:1062–1066)

Full access
in American Journal of Veterinary Research