The association between antibody titres againstCampylobacter fetus and milk production efficiency in dairy cattle |
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| Authors: | S Akhtar H P Riemann M C Thurmond C E Franti |
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| Institution: | (1) Department of Epidemiology and Preventive Medicine, School of Veterinary Medicine, University of California, 95616 Davis, CA, USA;(2) Present address: Animal Science Institute, National Agricultural Research Centre, Park Road, 45500 Islamabad, Pakistan |
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| Abstract: | The association between serological evidence of exposure toCampylobacter fectus and milk production performance was studied in 178 lactating cows from three California Dairy Herd Improvement Association herds using a cross-sectional study design in December 1986. ELISAs were used to determine the antibody titres againstCampylobacter fetus, Haemophilus somnus andLeptospira hardjo, which were classified as either negative or positive. The status of a cow as negative or positive againstC. fetus andH. somnus represents the serological evidence of natural exposure to the corresponding bacteria. However, the status againstL. hardjo was assumed to be the level of vaccinal titre against this organism since all the cows studied had been vaccinated against this agent. The data on demographic and productivity variables relating to the current lactation of the cows were obtained from Dairy Herd Improvement Association individual cow records for December 1986. Four measures of milk production efficiency for the current lactation were used. The status againstL. hardjo and other covariates suggested by previous studies were included in modelling the relationships of interest. Stepwise multiple linear regression was used to study the adjusted relationship ofC. fetus with each measure of milk production efficiency.Multivariate analyses revealed that the adjusted relationships ofC. fetus with the test-day's milk production, the extended 305-day milk production and the relative value of milk production were not significant (p>0.1). However, after adjusting for possible covariates,C. fetus-positive cows had an average of 7.43% lower mature equivalent milk production thanC. fetus-negative cows (p=0.02). Among the covariates, the serological status againstL. hardjo had a strong and independent relationship with the percentage mature equivalent milk production, the unstandardized partial regression coefficient being 4.53.We conclude from this cross-sectional study that the association ofC. fetus seropositivity with one index of milk production is the first indication that latentC. fetus infection may be associated with subclinical mastitis, perhaps through a hypersensitivity reaction. However, this needs further investigation.Abbreviations BMDP
Biomedical Computer Programs
- DHIA
California Dairy Herd Improvement Association
- ELISA
enzyme-linked immunosorbent assay; other abbreviations are shown in Table I |
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| Keywords: | antibody Campylobacter fetus cattle milk production serosurvey subclinical disease |
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