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Summary

Capsular polysaccharide (cp) of Pasteurella haemolytica, biotype A, serotype 1, was purified and combined with saline solution, aluminum hydroxide, and Freund's incomplete (oil) adjuvant. Three groups of calves were administered the various antigen preparations. The cp in saline preparation was also administered to 5 mature cows. Second injections were given 4 weeks after the first. Weekly obtained serum samples were analyzed for P haemolytica-specific antibody, using the indirect hemagglutination assay, and cp-specific antibodies were detected, using an isotype-specific elisa. Purified cp stimulated production of cp-specific IgM, IgG1, and IgG2 in calves and predominantly IgM and IgG1 in mature cows. Significant increases in cp antibody titers were not observed after the second injection of cp antigen in either calves or mature cows. The cp in oil adjuvant stimulated the highest mean cp-specific IgG1 and IgG2 responses, whereas the cp in aluminum hydroxide adjuvant stimulated the highest mean cp-specific IgM response.

Free access
in American Journal of Veterinary Research

SUMMARY

An epidemiologic study of Pasteurella haemolytica serovar 1 (Ph1) in market-stressed feeder calves from 7 farms in eastern Tennessee was conducted. The nasal mucus of each calf was cultured sequentially at the farm of origin (day 0), at an auction market (day 133), and at a feedyard in Texas (days 141, 148, 155, and 169). Of the 103 calves tested, 77 were culture-positive, including 1 on day 0, 1 on day 133, 20 on day 141, 57 on day 148, 50 on day 155, and 14 on day 169. From the 143 Ph1 isolates, 20 enzyme profiles were determined by use of a commercial enzyme system that detects 19 enzymatic reactions; 4 antimicrobial susceptibility profiles were obtained, using the disk-diffusion method, which evaluated susceptibility to 11 antibacterial drugs. All isolates were positive for acid phosphatase and alkaline phosphatase, but were negative for α-galactosidase, α-mannosidase, β-glucosidase, β-glucuronidase, cystine aminopeptidase, N-acetyl-β-glucosaminidase, and trypsin. Other positive enzyme reactions included: leucine aminopeptidase, 140 Ph1 isolates; phosphohydrolase, 90 isolates; α-fucosidase, 63 isolates; esterase (C4), 59 isolates; valine aminopeptidase, 30 isolates; esterase lipase (C8), 24 isolates; β-galactosidase, 2 isolates; and α-glucosidase, chymotrypsin and lipase (C14), 1 isolate each. Thirty-four Ph1 profiles were identified, using combined enzyme and antimicrobial susceptibility profiles. The data indicate that the strains isolated during the feedyard period may have been determined more by farm of origin (P ≤ 0.001) than by habitation with calves from other farms while in the feedyard. The combined enzyme and antimicrobial susceptibility profile method is a rapid and simple epidemiologic technique for tracking Ph1 strains in market-stressed feeder calves.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine whether increased conglutinin titers are evident in stressed calves that do not develop respiratory tract disease in feedlots,compared with respiratory tract disease, and to determine the increase in immunoconglutinin titers.

Animals—101 mixed-breed beef calves.

Procedure—Calves were processed at 4 farms of origin and allowed to remain with their dams for another 100 days. Calves from each farm were brought to a centrally located order-buyer barn. In a feedlot, 101 calves were assigned to pens and observed daily for clinical signs of acute respiratory tract disease. When sick calves were detected, they were treated with antibiotics and isolated in a pen for 4 days. Conglutinin and immunoconglutinin titers were determined for all calves.

Results—During the 28-day study, 73 calves developed respiratory tract disease, whereas 28 calves remained healthy. Mean conglutinin titers differed significantly among calves from the 4 farms. Significant differences were not detected in conglutinin titers among calves on the basis of sex, morbidity, or vaccination status against Mannheimia haemolytica at each farm, the order-buyer barn, or the feedlot on days 8, 15, and 28 after arrival. Immunoconglutinin titers in calves differed significantly among farms and morbidity status.

Conclusions and Clinical Relevance—Mean conglutinin titers in calves do not appear to be associated with the incidence of acute respiratory tract disease; however, increased immunoconglutinin titers appear to be associated with recovery of stressed calves from respiratory tract disease during the first 15 days after arrival in a feedlot. (Am J Vet Res 2000;61:1403–1409)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of tilmicosin treatment on number of Pasteurella haemolytica (PH) organisms in nasal secretion specimens of calves with respiratory tract disease.

Animals—206 British mixed-breed beef calves, 2 to 5 months old.

Procedure—In 2 separate studies of outbreaks, calves (study 1, n = 101; study 2, n = 105) that developed respiratory tract disease after transport to a feedlot were treated with tilmicosin. Nasal secretion specimens were examined for PH organisms to determine the status of colonization.

Results—In both studies, PH serotypes A1 and A6 were isolated. In study 1, tilmicosin treatment eliminated or markedly reduced the number of PH organisms in calves on days 1, 4, and 5 after treatment. In study 2, tilmicosin treatment eliminated PH organisms in calves on days 1, 2, 5, and 6 after treatment.

Conclusions and Clinical Relevance—Overall, tilmicosin treatment increased the number of culture-positive calves that became culture-negative and decreased the number of culture-negative calves that became culture-positive for up to 6 days after treatment. Tilmicosin treatment decreased the number of PH organisms in nasal secretion specimens, which indicated that fewer PH organisms were available to infect the lungs or to infect other calves. By reducing colonization, prophylactic use of tilmicosin before transport or at the time of arrival at a feedlot is likely to reduce the incidence of acute respiratory tract disease in calves for the initial several days after arrival, which is the period when they are most susceptible to infectious organisms. ( Am J Vet Res 2000;61: 525–529)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine effects of vaccination prior to transit and prophylactic administration of florfenicol at time of arrival at a feedyard on health of cattle and colonization of the nasopharynx by Mannheimia haemolytica (MH).

Animals—121 steers from Tennessee and 84 steers from New Mexico.

Procedure—Half of the steers were vaccinated before transport to a feedyard. Steers from Tennessee were vaccinated with MH bacterin-toxoid, and steers from New Mexico were vaccinated intranasally with modified-live leukotoxin-deficient MH. Half of the vaccinates and nonvaccinates were randomly selected to receive florfenicol on arrival at the feedyard. Steers were observed daily for respiratory tract disease (RTD).

Results—Administration of florfenicol at time of arrival reduced the incidence of RTD, delayed the interval before onset of RTD, and reduced the incidence of MH colonization of the nasopharynx for at least 4 days, but vaccination did not have any effect. Vaccination elicited an increase in serum antibody titers to MH. Administration of florfenicol at time of arrival reduced the development of serum antibody titers in intranasally vaccinated steers and both groups of nonvaccinated steers, but intranasal vaccination did not affect colonization by wild-type MH.

Conclusions and Clinical Relevance—Administration of florfenicol at time of arrival decreased the incidence of MH organisms in the nasopharynx and delayed the onset of RTD. Prophylactic use of suitable antibiotics is likely to reduce the incidence of acute RTD in calves for several days after arrival at feedyards, which is the period when they are most susceptible to infectious organisms. (Am J Vet Res 2002;63:251–256)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine the rate and mode of infectious spread of Pasteurella haemolytica among calves maintained under typical conditions during collection, transport, and the first month of feeding.

Animals

101 two- to five-month-old Angus-crossbred calves.

Procedure

Samples obtained from cattle prior to and after they were transported to a feedlot were used for isolation and characterization of P haemolytica. Samples were also obtained from additional calves, some of which were sick, and these calves were then commingled with the transported calves for 3 days. A strain of P haemolytica that contains a rare deletion of the 4.2-kilobase streptomycin- and sulfonamide-resistance plasmid was inoculated into both palatine tonsils of 12 calves. Nasal secretions were aspirated from the ventral nasal meatus. Tonsillar wash specimens were procured. Pasteurella haemolytica organisms were quantitatively cultured and identified on the basis of colony morphology and response to specific antisera. Plasmids were isolated by an alkaline lysis procedure and identified by agarose gel electrophoresis.

Results

A single plasmid profile was observed from P haemolytica isolated from samples obtained prior to shipment. Commingled calves were shedding P haemolytica containing each known plasmid profile. After shipment, samples contained P haemolytica isolates with each known plasmid profile. The plasmid profile of the unique P haemolytica isolate was recovered from all 12 inoculated calves and 10 other calves. Some calves simultaneously shed P haemolytica isolates with differing plasmid profiles.

Conclusions and Clinical Relevance

Pasteurella haemolytica serotype 1 was horizontally transmitted among calves within days of commingling, which continued after calves were transported to a feedlot. (Am J Vet Res 1998;59:401–405)

Free access
in American Journal of Veterinary Research

Abstract

Objectives

To follow incidence of Pasteurella haemolytica (PH) in the upper respiratory tract of healthy calves at the farm and through the marketing process, and to determine the effect of vaccination on PH colonization of the upper respiratory tract and on the incidence of respiratory tract disease (RTD).

Animals

2- to 5-month-old calves (n = 104) from 4 farms.

Procedure

Calves were vaccinated with a killed PH serotype-1 product. Nasal secretion and tonsil wash specimens were cultured for PH, and serum antibody was measured by indirect hemagglutination. Calves with RTD were treated with tilmicosin phosphate.

Results

At the feedyard, 73 calves had RTD. The incidence of RTD was significantly related to the farm of origin, and was inversely related to the PH serum titer at the farm, but was not influenced by vaccination. Isolations of PH serotype 1 however, were reduced by vaccination. The major serotypes of PH encountered were 1 and 6.

Conclusion

Vaccination can reduce the frequency of colonization of the uoper respiratory tract by PH. (Am J Vet Res 1936;57:1317-1320)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To identify cytocidal viruses and Pasteurella spp that could be isolated from cattle involved in 2 natural outbreaks of shipping fever.

Design—105 and 120 castrated male 4- to 8-monthold feedlot cattle involved in 1997 and 1998 outbreaks, respectively.

Animals—Nasal swab specimens and blood samples were collected, and cattle were vaccinated on arrival at an order-buyer barn from 4 local auction houses. Four days later, they were transported to a feedlot, and additional nasal swab specimens and blood samples were collected. Nasal swab specimens were submitted for virus isolation and bacterial culture; blood samples were submitted for measurement of respiratory bovine coronavirus (RBCV) hemagglutinin inhibition titers.

Results—93 of 105 cattle and 106 of 120 cattle developed signs of respiratory tract disease during 1997 and 1998, respectively, and RBCV was isolated from 81 and 89 sick cattle, respectively, while at the orderbuyer's barn or the day after arrival at the feedlot. During the 1997 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 4 cattle 14 days after arrival at the feedlot. During the 1998 outbreak, bovine herpesvirus 1 was isolated from 2 cattle at the order-buyer's barn and on arrival at the feedlot and from 5 cattle 7 and 14 days after arrival at the feedlot, and parainfluenza virus 3 was isolated from 1 animal the day of, and from 18 cattle 7 and 14 days after, arrival at the feedlot. Pasteurella spp was cultured from 4 and 6 cattle at the order-buyer's barn and from 92 and 72 cattle on arrival at the feedlot during the 1997 and 1998 outbreaks, respectively.

Conclusion and Clinical Relevance—Results suggest that RBCV may play a causative role in outbreaks of shipping fever in cattle. More than 80% of the sick cattle shed RBCV at the beginning of 2 outbreaks when the Pasteurella spp infection rate was low. (J Am Vet Med Assoc 2000;216:1599–1604)

Full access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To detect bovine adenovirus serotype 7 (BAV-7) infections in calves by use of viral isolation and serologic testing.

Animals—205 postweaning calves.

Procedure—121 calves were assembled by an order buyer through auction markets in eastern Tennessee and transported to New Mexico where they were commingled with 84 healthy ranch-reared calves. Tests included viral isolation in cell culture from peripheral blood leukocytes (PBL) and detection of serum BAV-7 antibodies by use of microtitration viral neutralization.

Results —BAV-7 was isolated from PBL of 8 calves and seroconversion to BAV-7 was detected for 38 of 199 (19.1%) calves. Concurrent bovine viral diarrhea virus infections were detected in most calves from which BAV-7 was isolated.

Conclusions and Clinical Relevance —Results of our study indicate that BAV-7 infections can be found in postweaning commingled calves and may develop more commonly in calves with concurrent infections with viruses such as bovine viral diarrhea virus (BVDV). (Am J Vet Res 2002;63:976–978).

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of transportation stress on serum concentrations of oxidative stress biomarkers of calves.

Animals—105 crossbred beef steer calves (mean [± SD] body weight, 207 ± 21.2 kg).

Procedure—Calves were assembled at 1 location in Tennessee, and pretransit (day –3) blood samples were collected. Calves were allotted randomly by body weight into 2 groups. Calves were transported 1,930 miles to a feedlot in Texas, and 1 group received tilmicosin phosphate (33 µg/kg, SC) upon arrival. Calves were weighed and blood samples collected on the day of arrival (day 1) and on days 15, 22, and 28. Calves were scored daily for signs of bovine respiratory disease (BRD). Serum total antioxidant capacity (TACA) and serum malondialdehyde (MDA) concentrations were determined.

Results—Transportation stress significantly decreased mean serum TACA concentrations (from 147 ± 31.2 U/mL to 133 ± 20.1 U/mL) and significantly increased serum MDA concentrations (from 10.9 ± 18.3 µg/mL to 30.2 ± 50.5 µg/mL). Calves that died had a 43% increase in serum MDA concentration on day 1, compared with calves that lived (42.2 ± 67.0 µg/mL vs 29.4 ± 49.4 µg/mL, respectively). Calves that had ≥ 3 episodes of BRD had 2-fold higher serum MDA concentrations on day 1 than healthy calves. Tilmicosintreated calves had a 20.8% significantly greater average daily gain and significantly greater serum TACA concentration than nontreated calves on day 28.

Conclusions and Clinical Relevance—Transportation stress increases serum concentrations of oxidative stress biomarkers that are related to episodes of BRD and mortality in calves. (Am J Vet Res 2004;65:860–864)

Full access
in American Journal of Veterinary Research