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Genetic Susceptibility to Neospora caninum Infection in Holstein Cattle in Ontario

¹ CGIL, Department of Animal and Poultry Science, University of Guelph, Ontario, Canada N1G 2W1
² Department of Population Medicine, University of Guelph, Ontario, Canada N1G 2W1
³ California Animal Health & Food Safety Laboratory System, University of California, Davis 95616
⁴ Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Lennoxville, Quebec, Canada J1M 1Z3
⁵ Department of Pathobiology, University of Guelph, Ontario, Canada N1G 2W1

Corresponding author: A. S. Peregrine; e-mail: aperegri{at}ovc.uoguelph.ca.

Neospora caninum has been reported to be an important cause of endemic fetal loss and occasional abortion epidemics in cattle around the world. This study examined 12,016 sera collected from 9723 Holstein cows on 125 herds across Ontario in 1998, 1999, and 2000. An enzyme-linked immunosorbent assay was used to examine the sera for antibodies to N. caninum. The overall prevalence of N. caninum antibodies in the cattle was 11.2% and the prevalence in individual herds varied from 0 to 70.4%. Among 3109 daughter-dam pairs, 619 positive dams had 252 positive daughters, giving a detected vertical transmission rate of 40.7%. In contrast, there were only 6.7% positive daughters from negative dams (167 of 2490). Pedigree edits left 8031 cows with 1463 sires for estimation of heritability. Five genetic models (sire model, animal model, sire-dam model, a sire-maternal grandsire model, and a maternal effects model) with fixed effects of bleeding year-month, age of the animals, and herd were fitted to the data. The estimated heritability of susceptibility to N. caninum ranged between 0.084 and 0.124. The sire-maternal grandsire model and the maternal effects model provided better fit than the other models because the maternal genetic variance was much greater than the direct genetic variance. To reduce the incidence of N. caninum infection, more emphasis should be placed on management practices than on genetic selection.

Key Words: Neospora caninum • genetic susceptibility • dairy cattle

Abbreviation key: AIC = Akaike information criterion, AM = animal model, AMM = animal maternal effects model, MSE = mean square error, SDM = sire-dam model, SGM = sire-maternal grandsire model, SM = sire model, S/P = sample-to-positive.

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				J. P. Dubey, G. Schares, and L. M. Ortega-Mora Epidemiology and Control of Neosporosis and Neospora caninum Clin. Microbiol. Rev., April 1, 2007; 20(2): 323 - 367. [Abstract] [Full Text] [PDF]