Search Results

Abstract

Objective—To determine whether vaccinated or conditioned feeder calves sold through special auctions in Ontario commanded a premium, compared with feeder calves sold at conventional auctions, and whether various physical characteristics of the calves were associated with the sale price.

Design—Cross-sectional study.

Animals—14,037 calves sold through conventional and special auctions at the Keady Livestock Market during the fall of 1999 and 2000.

Procedure—Calves were observed as they were sold by lot in the auction ring. Lot characteristics and the price received for each lot were recorded. Multivariate analysis was used to estimate the effect of lot characteristics and sale type on price.

Results—Information was recorded for 2,601 calf lots. Multivariate analysis indicated that various lot characteristics were associated with sale price, with 68% of the variation explained by the model. Overall, lots sold at special auctions received a premium of $0.06/lb (Canadian dollars), compared with lots sold at conventional auctions. However, the premium varied with mean body weight of the lot and year. In addition, frame size, breed, body condition score, uniformity of the lot, weaning status, mean body weight, lot size, sex, year, and sale type were significantly related to sale price.

Conclusions and Clinical Relevance—Results suggested that producers selling calves at special auctions at this market received a premium, compared with producers selling calves at conventional auctions. (J Am Vet Med Assoc 2003;223:670–676)

Abstract

Objective—To compare health performance during the first 28 days in the feedlot for vaccinated or conditioned feeder calves sold through special auctions in Ontario with health performance for calves sold through conventional auctions in the province.

Design—Cohort study.

Animals—12,313 calves sold through conventional and special auctions at the Keady Livestock Market during the fall of 1999 and 2000.

Procedure—Buyers of calf groups were approached at the auction market or contacted by telephone and asked to record the number of calves requiring treatment for bovine respiratory tract disease (BRD) during the first 28 days after purchase.

Results—211 calf groups (≥ 20 calves/group) were followed up for 28 days after purchase. Multivariate logistic analysis indicated that vaccinated calves purchased through special auctions were 0.68 (95% confidence interval, 0.50 to 0.93) times as likely to receive treatment for BRD as were calves purchased at conventional auctions and that conditioned calves were 0.22 (95% confidence interval, 0.12 to 0.38) times as likely to receive treatment. Groups that received antimicrobials by injection on arrival at the feedlot were 0.64 (95% confidence interval, 0.43 to 0.96) times as likely to be treated as were groups that did not.

Conclusions and Clinical Relevance—Results suggest that vaccinated and conditioned calves were less likely to receive treatment for BRD during the first 28 days in the feedlot; however, there was no difference in mortality rate. (J Am Vet Med Assoc 2003;223: 677–683)

Abstract

Objective—To determine the prevalence of Mycoplasma bovis infection in the lungs of cattle at various times after arrival at a feedlot, to measure the relationship between clinical disease status and the concentration and genotype of M bovis within the lungs, and to investigate changes in the genotype of M bovis over time.

Sample—Bronchoalveolar lavage fluid (BALF) from 328 healthy or pneumonic beef cattle and 20 M bovis isolates obtained from postmortem samples.

Procedures—The concentration of M bovis in BALF was determined via real-time PCR assays, and M bovis isolates from BALF were genotyped via amplified fragment length polymorphism (AFLP) analysis.

Results—Prevalence of M bovis in BALF was 1 of 60 (1.7%) at arrival to a feedlot and 26 of 36 (72.2%) and 36 of 42 (85.7%) at ≤ 15 days and 55 days after arrival, respectively. Neither the concentration nor the AFLP type of M bovis in BALF was correlated with clinical disease status. The M bovis AFLP type differed between early and later sampling periods in 14 of 17 cattle.

Conclusions and Clinical Relevance—The findings implied spread of M bovis among calves and suggested that host factors and copathogens may determine disease outcomes in infected calves. Chronic pulmonary infection with M bovis may represent a dynamic situation of bacterial clearance and reinfection with strains of different AFLP type, rather than continuous infection with a single clone. These findings impact our understanding of why cattle with chronic pneumonia and polyarthritis syndrome inadequately respond to antimicrobial treatment.