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Veterinary Archives, Vol.79 No.4 July 2009. -

The objective of this retrospective cohort study was to evaluate the efficacy of selected Johne’s-disease control measures on a dairy farm. The Dairy Comp 305 archive files for 455 Holstein dairy cows born in 1996, 1997 and 1998 were used. The tested heifers were grouped into annual birth cohorts. Kinetic ELISA KELA results and fecal-culture results for solid- HEYM and liquid-media systems ESP Culture System II were described and compared between birth cohorts. Only one animal had a high KELA score. Nevertheless, the

fecal-culture results showed that there were animals shedding in the highest category even in test year 2001 in all birth cohorts. The 1997 birth cohort showed a lower rate of fecal positive culture results compared to the 1996 and 1998 cohorts. Out of 455 cows in the study, 43 were culled because of Johne’s disease clinical signs or high fecal-culture results. This cause-specific cull risk was 20% 21-105 animals in 1996, 12% 12-100 animals in 1997 and 10% 10-100 animals in 1998. Survival analysis, where animals were classified according to the KELA and fecal-culture results for all animals tested as heifers, showed that heifers with the highest KELA value and-or the highest fecal-culture results had the shortest survival time in the herd. Analysis of birth cohorts led to an enhanced understanding of the response to the Johne’s-control procedures. In this herd, early shedding led to short herd-survival.

Johne’s disease; control; dairy farm; fecal culture



Autor: Goran Bačić - ; Clinic for Reproduction and Obstetrics, Faculty of Veterinary Medicine, Zagreb, Croatia Korana Stipetić - ; De

Fuente: http://hrcak.srce.hr/



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