A case-control study of Nocardia mastitis in Nova Scotia dairy herds   总被引：1，自引：0，他引：1       下载免费PDF全文

Ferns L  Dohoo I  Donald A 《The Canadian veterinary journal. La revue veterinaire canadienne》1991,32(11):673-677

A case-control study was conducted to identify herd production, housing, and hygienic and therapeutic factors associated with a diagnosis of Nocardia mastitis in dairy herds in Nova Scotia. The data were collected by on-farm interviews with owners of 54 case and 54 control herds.

Logistic regression was used to study risk factors. The use of dry cow products containing neomycin, including two specific dry cow products, was strongly associated with a diagnosis of Nocardia mastitis in a herd. Other factors which increased the risk of Nocardia mastitis were higher levels of production, larger herd size, and a large percentage of cows treated with dry cow products. These results are compared to results from a similar study carried out in Ontario.

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Animal productivity and health information network   总被引：4，自引：3，他引：1       下载免费PDF全文

Dohoo IR 《The Canadian veterinary journal. La revue veterinaire canadienne》1988,29(3):281-287

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Cost of extended open period in dairy cattle   总被引：4，自引：2，他引：2       下载免费PDF全文

Dohoo IR 《The Canadian veterinary journal. La revue veterinaire canadienne》1982,23(7):229-230

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Relationships between bulk-tank antibodies to Ostertagia ostertagi and herd-management practices and measures of milk production in Nova Scotia dairy herds     

Guitián FJ  Dohoo IR  Markham RJ  Conboy G  Keefe GP 《Preventive veterinary medicine》1999,47(1-2):79-89

Monthly bulk-tank milk samples were obtained from 415 Nova Scotia dairy herds in each of the months of July-September 1998 and tested using an indirect microtitre ELISA against a crude saline-extract, whole-worm Ostertagia ostertagi antigen. ELISA results (optical densities (ODs)) were consistent across months (r=0.85) but there was considerable variation among herds. A questionnaire was sent by mail to all producers; information on management factors that would potentially influence parasite burdens in the herds was obtained from 239 farms. Data on annual milk production, summer milk production (July-September) and seasonal decline in milk production were obtained from the Animal Productivity and Health Information Network (APHIN) database. Associations between management practices and ODs, and between ODs and milk-production parameters were studied. Some management practices known to be associated with parasite burdens had expected directions of association with the ODs, giving supporting evidence that the ELISA is a reasonable measure of parasite burden. Most notably, ODs were increased with greater exposure of heifers or milking cows to pasture. ODs were not associated with either annual milk production or seasonal decline in milk production. However, there was a substantial relationship between the herd OD value and the level of milk production during the summer. An increase in the OD from 0.58 to 0.83 (the interquartile range of ODs) was associated with a reduction in production of 1.25kg/cow/day.  相似文献   

A bulk tank milk survey of Ostertagia ostertagi antibodies in dairy herds in Prince Edward Island and their relationship with herd management factors and milk yield          下载免费PDF全文

Sanchez J  Dohoo I 《The Canadian veterinary journal. La revue veterinaire canadienne》2002,43(6):454-459

The objective of this study was to quantify the relationship of the levels of antibodies to Ostertagia ostertagi in bulk-tank milk samples from Prince Edward Island (PEI) dairy farms to milk production and to herd-management practices potentially related to gastrointestinal nematode infections. The milk samples were obtained from 289 to 322 dairy farms during 2000; production and management data were available from 197 and 200 farms, respectively. Cow exposure to pasture and whole-herd anthelmintic treatment were the only herd management variables significantly associated with antibody levels in the fall of 2000. An increase in antibody levels from the observed 25th percentile to the 75th percentile (interquartile range) was associated with a drop in milk production of 1.2 kg/cow/day. The results of this study indicate that the enzyme-linked immunosorbent assay for O. ostertagi antibody is a potentially useful technique to measure parasite exposure in adult dairy cows and that parasite burdens in lactating cattle in PEI have an important impact on milk production.  相似文献   

A longitudinal study of gastrointestinal parasites in Canadian dairy farms. The value of an indirect Ostertagia ostertagi ELISA as a monitoring tool     

Sanchez J  Dohoo I  Nødtvedt A  Keefe G  Markham F  Leslie K  DesCôteaux L  Campbell J 《Veterinary parasitology》2002,107(3):209-226

The general objective of this study was to evaluate a crude Ostertagia ostertagi antigen enzyme-linked immunosorbent assay (ELISA) for monitoring gastrointestinal parasites in lactating dairy cattle. A longitudinal study of gastrointestinal parasites in lactating dairy cows was carried out in 38 herds in four provinces of Canada (Prince Edward Island, Quebec, Ontario and Saskatchewan) from September 1999 to October 2000. Bulk tank milk, cow milk, serum and fecal samples were collected monthly or quarterly from all these farms. Information on herd management factors was collected by a standard questionnaire and individual cow production data were obtained from an electronic database. The overall mean optical density ratio (ODR) was 0.30 and ranged from -0.05 to 1.55. Although a clear seasonal pattern was not observed, the ODR values tended to decrease during the housing period and start increasing in the spring before the cows went out to pasture. The second and third or greater lactation cows had significantly higher ODR values compared with first lactation animals. The individual cow ODR had a very low correlation with individual squared root fecal egg counts but showed a reasonably high correlation when herd averages values were computed (r=0.73). A moderate correlation (r approximately 0.50) between the bulk tank and herd average ODR was observed. Milk yield was negatively associated with individual cow milk ODR and a quadratic effect on ODR was observed for days in milk. Twenty-eight of the herds participated in a clinical trial of eprinomectin (Ivomec Eprinex) treatment at calving. The cow level ODR values determined late in the previous lactation had a marginally significant effect (P=0.07) on treatment response, suggesting that high OD cows responded better to the anthelmintic treatment. However, because of the small sample size available in this model, more research is needed to better understand this relationship. In conclusion, the indirect ELISA using an O. ostertagi crude antigen appears useful as a technique for monitoring gastrointestinal parasite burdens in adult dairy cows and holds promise as a potential predictor of response to anthelmintic treatment.  相似文献   

Age pattern of mortality in eight breeds of insured dogs in Sweden     

Egenvall A  Bonnett BN  Shoukri M  Olson P  Hedhammar A  Dohoo I 《Preventive veterinary medicine》2000,46(1):1-14

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Application of Quantitative Methods in Veterinary Epidemiology          下载免费PDF全文

Ian Dohoo 《The Canadian veterinary journal. La revue veterinaire canadienne》1998,39(6):372

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A survey of sheep diseases in Canada.   总被引：2，自引：1，他引：1       下载免费PDF全文

I R Dohoo  R A Curtis    G G Finley 《Canadian journal of veterinary research》1985,49(3):239-247

A mail survey of disease occurrence in Canadian sheep flocks was conducted. The survey, which covered the period from September 1982 to August 1983, utilized flocks on the Record of Performance (ROP) sheep program and relatively complete data were available from 116 flocks. Data about lambing rates, incidence of a variety of lamb and ewe diseases and reasons for culling were obtained. At the same time a retrospective evaluation of records of diagnoses of sheep diseases recorded at diagnostic laboratories across the country was performed. Data from the years 1978 to 1982 were obtained and summarized. A lambing percentage of 153% (1.53 lambs live born per ewe lambing) was observed and an additional 0.05 lambs were stillborn. The major identified causes of mortality amongst lambs were starvation, pneumonia, scours and accidents. Pasteurella spp. were the etiological agents most commonly associated with pneumonia in lambs and Escherichia coli had the same predominant position with regards to nonparasitic scours. A large discrepancy existed between the proportional mortality rates for internal parasites and coccidiosis as determined from the farm survey data compared to diagnostic laboratory data. This suggests that clinical parasitism may not be adequately recognized at the farm level. Abortions in ewes occurred in approximately half the flocks, but generally at a low level and no severe abortion storms occurred. Pneumonia was the most commonly identified cause of mortality in ewes and although Pasteurella spp. appear to be the most important etiological agents, regional differences were apparent.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Report of the Meeting of the Section Virology at Wageningen (The Netherlands), 7–11 June 1971     

Dr IR J. A. De Bokx 《Potato Research》1971,14(3):237-242

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