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  • Author or Editor: David E. Amrine x
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Abstract

Objective—To assess biometric tools for gait analysis in healthy calves by use of pressure mat sensors, a handheld algometer, and serial circumferential measurements of selected joints.

Animals—20 six- to eight-week-old healthy male Holstein calves.

Procedures—Calves were evaluated over a 4-day period. Gait analysis was performed by training calves to walk over a pressure-sensitive mat, which recorded quantitative measurements. An algometer was applied perpendicular to each joint until an aversion response was observed or a preset limit of 50 N/cm2 was obtained. Circumference measurements of the carpal and tarsal joints were obtained by the application of a flexible measuring tape to defined areas of each limb. Variability between joint circumference measurements and pressure mat variables were analyzed with a standard least squares means model. Algometer measurements were dichotomized, and logistic regression was used to assess the probability that a calf reacted to algometer-applied pressure.

Results—1 calf was removed from the study because of lameness. Mean carpal and tarsal joint circumference measurements were reliable and consistent among calves. Algometry results suggested that healthy calves were more sensitive to pressure applied to the elbow and stifle joints, compared with pressure applied to the carpal, tarsal, and metacarpophalangeal or metatarsophalangeal joints. Pressure mat variables of stance time and stride velocity varied greatly among calves, whereas impulse and maximum forces varied little.

Conclusions and Clinical Relevance—Findings can serve as reference points for other studies and be used for comparison with results for calves with lameness or altered gaits.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To determine the precision of a clinical illness score (CIS) system for identification of clinical signs in calves with experimentally induced Mycoplasma bovis pneumonia and to evaluate the accuracy of CISs in relation to pulmonary consolidation scores assigned at necropsy.

Animals—178 Holstein bull calves that were 52 to 91 days of age at the time of pneumonia induction.

Procedures—5 trials involved calves challenged with M bovis and scheduled for euthanasia and necropsy 12 to 24 days afterward. Nine veterinarian observers with various degrees of experience simultaneously assigned CISs to calves within 48 hours before necropsy. The precision of the CIS system among observers was evaluated via the Cohen κ statistic. The accuracy of each observer's CISs relative to 6 cutoffs (≥ 5%, ≥ 10%, ≥ 15%, ≥ 20%, ≥ 25%, and ≥ 30%) of percentage pulmonary consolidation was determined by comparing prenecropsy CISs with the gross pulmonary consolidation scores assigned at necropsy. Estimates for sensitivity and specificity were calculated relative to the 6 pulmonary consolidation cutoffs.

Results—A slight level of agreement was evident among observers (κ range, 0.10 to 0.21 for the individual trials) and overall (κ = 0.16; 95% confidence interval, 0.10 to 0.24). Median sensitivity and specificity changed with pulmonary consolidation score cutoff. Median sensitivity for all observers ranged from 81.7% to 98.9%, and median specificity ranged from 80.8% to 94.9% over all cutoff values.

Conclusions and Clinical Relevance—Agreement among observers assigning CISs to calves was low; the accuracy of the CIS system in relation to that of pulmonary consolidation scoring varied with the severity of consolidation considered to represent bovine respiratory disease.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate associations between weather conditions and management factors with the incidence of death attributable to bovine respiratory disease complex (BRDC) in high-risk auction-sourced beef calves.

ANIMALS

Cohorts (n = 3,339) of male beef calves (545,866) purchased by 1 large cattle feeding operation from 216 locations and transported to 1 of 89 feeding locations (backgrounding location or feedlot) with similar management protocols.

PROCEDURES

Associations between weather conditions and management factors on the day of purchase (day P) and during the first week at the feeding location and cumulative BRDC mortality incidence within the first 60 days on feed were estimated in a mixed-effects negative binomial regression model.

RESULTS

Significant factors in the final model were weaning status; degree of com-mingling; body weight; transport distance; season; precipitation, mean wind speed, and maximum environmental temperature on day P; environmental temperature range in the first week after arrival at the feeding location; and interactions between distance and wind speed and between body weight and maximum environmental temperature. Precipitation and wind speed on day P were associated with lower cumulative BRDC mortality incidence, but wind speed was associated only among calves transported long distances (≥ 1,082.4 km). Higher mean maximum temperature on day P increased the incidence of cumulative mortality among calves with low body weights (< 275.5 kg).

CONCLUSIONS AND CLINICAL RELEVANCE

Several weather conditions on day P and during the first week after arrival were associated with incidence of BRDC mortality. The results may have implications for health- and economic-risk management, especially for high-risk calves and calves that are transported long distances.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To determine the relationship between rectal temperature at first treatment for bovine respiratory disease complex (BRDC) in feedlot calves and the probability of not finishing the production cycle.

Design—Retrospective data analysis.

Animals—344,982 calves identified as having BRDC from 19 US feedlots from 2000 to 2009.

Procedures—For each calf, data for rectal temperature at initial treatment for BRDC and various performance and outcome variables were analyzed. A binary variable was created to identify calves that did not finish (DNF) the production cycle (died or culled prior to cohort slaughter). A mixed general linear model and receiver operating characteristic curve were created to evaluate associations of rectal temperature, number of days in the feedlot at time of BRDC diagnosis, body weight, quarter of year at feedlot arrival, sex, and all 2-way interactions with rectal temperature with the probability that calves DNF.

Results—27,495 of 344,982 (7.97%) calves DNF. Mean rectal temperature at first treatment for BRDC was 40.0°C (104°F). As rectal temperature increased, the probability that a calf DNF increased; however, that relationship was not linear and was influenced by quarter of year at feedlot arrival, sex, and number of days in the feedlot at time of BRDC diagnosis. Area under the receiver operating characteristic curve for correct identification of a calf that DNF was 0.646.

Conclusions and Clinical Relevance—Rectal temperature of feedlot calves at first treatment for BRDC had limited value as a prognostic indicator of whether those calves would finish the production cycle.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine the effect of transportation during periods of high ambient temperature on physiologic and behavioral indices of beef heifers.

Animals—20 heifers (mean body weight, 217.8 kg).

Procedures—Ten heifers were transported 518 km when the maximum ambient temperature was ≥ 32.2°C while the other 10 heifers served as untransported controls. Blood samples were collected from transported heifers at predetermined intervals during the transportation period. For all heifers, body weights, nasal and rectal temperatures, and behavioral indices were measured at predetermined intervals for 3 days after transportation. A week later, the entire process was repeated such that each group was transported twice and served as the control twice.

Results—Transported heifers spent more time near the hay feeder on the day of transportation, had lower nasal and rectal temperatures for 24 hours after transportation, and spent more time lying down for 2 days after transportation, compared with those indices for control heifers. Eight hours after transportation, the weight of transported heifers decreased 6%, whereas that of control heifers increased 0.6%. At 48 hours after initiation of transportation, weight, rectal temperature, and time spent at various pen locations did not differ between transported and control heifers. Cortisol concentrations were higher 4 hours after initiation of transportation, compared with those determined just prior to transportation.

Conclusions and Clinical Relevance—Results indicated transportation during periods of high ambient temperatures caused transient changes in physiologic and behavioral indices of beef heifers.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To assess a commercially available point-of-care assay for measurement of bovine cardiac troponin I (cTnI) concentration in blood and plasma samples.

Sample—Prepared bovine plasma standard samples with known concentrations (0 to 1.0 ng/mL) of cTnI and blood and plasma samples obtained from 28 healthy 2.5-month-old Holstein calves.

Procedures—Coefficients of variation were calculated for concentrations of cTnI in prepared standards determined with the point-of-care assay, and values were compared with the known concentrations. The cTnI concentrations in blood samples obtained from calves determined with the point-of-care assay were compared with cTnI concentrations in plasma samples obtained from those animals determined with a validated immunoassay.

Results—The coefficients of variation of cTnI concentrations determined for prepared standards by use of the point-of-care assay were low (< 20%) for standards with cTnI concentrations ≥ 0.025 ng/mL. The blood cTnI concentrations determined with the point-of-care assay were not significantly different from the plasma cTnI concentrations determined with the validated immunoassay.

Conclusions and Clinical Relevance—Results of this study indicated the point-of-care assay had high precision for determination of cTnI concentrations in most evaluated prepared bovine plasma standard samples. The point-of-care assay may be useful for determination of circulating concentrations of cTnI in cattle.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To determine associations of blood analysis variables and orbit and nasal planum surface temperatures with the onset and severity of Mycoplasma bovis pneumonia in calves.

Animals—28 healthy calves.

Procedures—Calves were challenged with M bovis (n = 24) on day 0 or not challenged (4). Blood samples were obtained for cardiac troponin I, CBC, and serum biochemical analyses on various days. Orbit and nasal planum surface temperatures were determined with infrared thermography on various days. Calves were euthanized, gross necropsies were performed, heart and lung samples were collected for histologic evaluation, and microbial cultures of lung samples were performed on day 14. Pneumonia severity was categorized as mild (< 10% lung consolidation) or moderate (≥ 10% lung consolidation). Associations between measured variables and severity of pneumonia or sample collection day were determined.

Results—Plasma cardiac troponin I concentration for the 28 calves was significantly higher on day 14 than it was on day 0 or 7 (least squares mean, 0.02, 0, and 0 ng/mL, respectively). No other variables changed significantly during the study. No substantial gross or histologic abnormalities were identified in cardiac muscle samples. Day 14 plasma fibrinogen concentration was significantly different between calves with mild pneumonia and those with moderate pneumonia (mean, 0.44 and 0.74 g/dL, respectively). Calves with moderate pneumonia had significantly lower least squares mean surface temperature of the dorsal aspect of the nasal planum (18.7°C) versus calves with mild pneumonia (22.9°C).

Conclusions and Clinical Relevance—Results indicated the evaluated variables had low value for assessment of bovine respiratory disease complex in calves.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine whether animal-to-animal and community contact patterns were correlated with and predictive for bovine respiratory disease (BRD) in beef steers during the first 28 days after feedlot entry.

ANIMALS 70 weaned beef steers (mean weight, 248.9 kg).

PROCEDURES Calves were instrumented with a real-time location system transmitter tag and commingled in a single pen. The location of each calf was continuously monitored. Contact between calves was defined as ≤ 0.5 m between pen coordinates, and the duration that 2 calves were within 0.5 m of each other was calculated daily. Bovine respiratory disease was defined as respiratory tract signs and a rectal temperature > 40°C. Locational data were input into a community detection program to determine daily calf contact and community profiles. The number of BRD cases within each community was determined. A random forest algorithm was then applied to the data to determine whether contact measures were predictive of BRD.

RESULTS Probability of BRD was positively correlated with the number of seconds a calf spent in contact with calves presumably shedding BRD pathogens and number of calves with BRD within the community on the day being evaluated and the previous 2 days. Diagnostic performance of the random forest algorithm varied, with the positive and negative predictive values generally < 10% and > 90%, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that direct transmission of BRD pathogens likely occurs among feedlot cattle. The relative contribution of animal-to-animal contact to BRD risk remains unknown and warrants further investigation.

Restricted access
in American Journal of Veterinary Research