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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.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE To assess the use of 3-D accelerometers to evaluate behavioral changes in cattle experimentally infected with a low-virulent strain of bovine viral diarrhea virus (BVDV).

ANIMALS 20 beef steers (mean weight, 238 kg).

PROCEDURES Calves were allocated to a BVDV (n = 10) or control (10) group. On day 0, calves in the BVDV group were inoculated with a low-virulent strain of BVDV (4 × 106 TCID50, intranasally), and calves in the control group were sham inoculated with BVDV-free medium (4 mL; intranasally). An accelerometer was affixed to the right hind limb of each calf on day −7 to record activity (lying, walking, and standing) continuously until 35 days after inoculation. Baseline was defined as days −7 to −1. Blood samples were collected at predetermined times for CBC, serum biochemical analysis, virus isolation, and determination of anti-BVDV antibody titers.

RESULTS All calves in the BVDV group developed viremia and anti-BVDV antibodies but developed only subclinical or mild disease. Calves in the control group did not develop viremia or anti-BVDV antibodies. Mean time allocated to each activity did not differ significantly between the BVDV and control groups on any day except day 8, when calves in the BVDV group spent less time standing than the calves in the control group. Following inoculation, calves in both groups tended to spend more time lying and less time walking and standing than they did during baseline.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that behavioral data obtained by accelerometers could not distinguish calves subclinically infected with BVDV from healthy control calves. However, subtle changes in the behavior of the BVDV-infected calves were detected and warrant further investigation.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To characterize clinical and behavioral changes in calves following inoculation with Mycoplasma bovis and evaluate relationships between those changes and pulmonary disease.

Animals—22 healthy Holstein steers.

Procedures—20 calves were inoculated intranasally with < 108 CFU or > 109 CFU of M bovis. Calves were assigned a clinical illness score (CIS) on a scale of 1 through 4 twice daily on the basis of severity of cough, labored breathing, and lethargy. For each calf, distance traveled and time spent near the waterer, feed bunk, or shelter were determined via a remote location monitoring device. Calves were euthanized and necropsied 22 days after inoculation.

Results—13 calves became clinically ill after challenge inoculation; 3 calves were euthanized within 20 days. Among all calves, consolidation was evident in 0% to 79.9% of the lungs; extent of lung consolidation did not differ between the challenge dose groups. Distance traveled and percentages of time spent in proximity to the feed bunk and shelter were associated with CIS; calves with more severe disease traveled less distance and spent less time at the feed bunk and more time in the shelter. Distance traveled by calves was negatively associated with extent of lung consolidation (< or ≥ 10% of lungs affected); this effect was modified by trial day.

Conclusions and Clinical Relevance—Following inoculation with M bovis, calf behavior patterns were associated with both CIS and severity of pulmonary disease. Use of behavior monitoring systems may aid in recognition of respiratory tract disease in calves.

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in American Journal of Veterinary Research

Abstract

Objective—To examine behavioral and physiologic effects of lipopolysaccharide (LPS)-induced mastitis in lactating dairy cows.

Animals—20 Holstein cows.

Procedures—Cows were assigned to 5 blocks (4 cows/block) on the basis of parity and number of days in lactation. Intramammary infusion and IV treatments were assigned in a 2 × 2 factorial arrangement. Cows within each block were assigned to receive intramammary infusion with 25 μg of LPS or sterile PBS solution 3 hours after milking, and treatment with flunixin meglumine or sterile PBS solution was administered IV 4 hours after intramammary infusion. Video monitoring was continuously performed during the study.

Results—LPS-infused cows spent less time during the first 12 hours after infusion lying, eating, and chewing cud, compared with results for PBS solution-infused cows. Behavioral responses were correlated with physiologic responses for the first 12 hours after intramammary infusion. Flunixin meglumine administration after intramammary infusion mitigated some behavioral and clinical systemic responses.

Conclusions and Clinical Relevance—Intramammary infusion of LPS caused changes in both behavioral and physiologic variables in lactating dairy cows. Time spent lying, eating, and chewing cud were negatively correlated with physiologic responses in cows. Evaluation of behavior patterns may provide an ancillary measure, along with evaluation of physiologic variables, for monitoring well-being, clinical responses, and recovery from acute clinical mastitis.

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in American Journal of Veterinary Research

Abstract

Objective—To describe daily, hourly, and animal-to-animal effects on lying behavior in steers.

Animals—25 crossbred beef steers.

Procedures—Wireless accelerometers were used to record behavioral data for cattle housed in a drylot cattle research facility during two 20-day periods (winter 2007 [n = 10 steers] and spring 2008 [15]). Behavioral data were categorized into lying, standing, and walking behaviors for each time point recorded. Logistic regression models were used to determine potential associations between the percentage of time spent lying and several factors, including time (hour) of day, day of trial, and steer.

Results—Lying behavior was significantly associated with hour of day, and a distinct circadian rhythm was identified. Steers spent > 55% of the time between 8:00 pm and 4:00 am lying and were most active (<30% lying behavior) during feeding periods (6:00 am to 7:00 am and 4:00 pm to 5:00 pm). Model-adjusted mean percentage of time spent lying was significantly associated with study day and was between 45% and 55% on most (27/40 [67.5%]) days. Lying behavior varied significantly among steers, and mean ± SD percentage of time spent lying ranged from 28.9 ± 6.1 % to 66.1 ± 6.6%.

Conclusions and Clinical Relevance—Cattle had distinct circadian rhythm patterns for lying behavior, and percentage of time spent lying varied by day and among steers. Researchers need to account for factors that affect lying patterns of cattle (ie, time of day, day of trial, and individual animal) when performing research with behavioral outcomes.

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in American Journal of Veterinary Research

Abstract

Objective—To determine the accuracy of accelerometers for measuring behavior changes in calves and to determine differences in beef calf behavior from before to after castration.

Animals—3 healthy Holstein calves and 12 healthy beef calves.

Procedures—2-dimensional accelerometers were placed on 3 calves, and data were logged simultaneous to video recording of animal behavior. Resulting data were used to generate and validate predictive models to classify posture (standing or lying) and type of activity (standing in place, walking, eating, getting up, lying awake, or lying sleeping). The algorithms developed were used to conduct a prospective trial to compare calf behavior in the first 24 hours after castration (n = 6) with behavior of noncastrated control calves (6) and with presurgical readings from the same castrated calves.

Results—On the basis of the analysis of the 2-dimensional accelerometer signal, posture was classified with a high degree of accuracy (98.3%) and the specific activity was estimated with a reasonably low misclassification rate (23.5%). Use of the system to compare behavior after castration revealed that castrated calves spent a significantly larger amount of time standing (82.2%), compared with presurgical readings (46.2%).

Conclusions and Clinical Relevance—2-dimensional accelerometers provided accurate classification of posture and reasonable classification of activity. Applying the system in a castration trial illustrated the usefulness of accelerometers for measuring behavioral changes in individual calves.

Restricted access
in American Journal of Veterinary Research

Abstract

Objective—To investigate the relationship of litter box location as it relates to cats' use of space in the house, elimination problems, and certain behaviors associated with elimination.

Sample Population—40 cats in single-cat house-holds with or without elimination behavior problems (20 cats/group).

Procedures—Camcorders were used to record the cats' behaviors at the litter box and other areas in which they eliminated during a 72-hour period. Use of space in the house was recorded by direct observation during 400 minutes of the 72-hour period. Elimination behaviors and other cat- and litter box–associated variables were compared between groups; litter box location with respect to inappropriate elimination was assessed.

Results—Litter box location did not differ between cats with and without elimination behavior problems. An inverse correlation was found between time spent sniffing and the distance of the litter box from the central core area. Cats with elimination problems spent significantly less time digging at the litter box than cats without elimination problems. There was no significant difference in the time spent pawing in litter box, sniffing, or covering excreta after elimination between the 2 groups of cats.

Conclusions and Clinical Relevance—Times spent digging in litter boxes by cats with and without elimination problems have been determined, and data suggest that actual digging times could be used as a means to test for litter preference and litter aversion. This information may also be used to identify cats with litter aversion prior to the development of an elimination problem.

Restricted access
in American Journal of Veterinary Research