title: Evaluation of anti-Ostertagia ostertagi antibodies in individual milk samples as decision parameter for selective anthelmintic treatment in dairy cows.
abstract: The aim of this study was to explore whether anti-Ostertagia ostertagi antibody levels measured by ELISA in individual milk samples hold promise as a decision parameter for either herd-level decisions or selective anthelmintic treatments by investigating (1) the relationship between individual and bulk-tank milk ELISA results; (2) the relationships of individual milk ELISA results with non-parasitic cow factors and (3) the relationship between individual milk ELISA results and the milk production response after anthelmintic treatment. Twelve farms were randomly allocated to a whole-herd treatment with eprinomectin or a placebo in October 2004 and individual milk samples and a bulk-tank milk sample were collected 1 month before and 1 month after treatment. Linear mixed models were used to investigate the associations of ELISA results with (a) breed, actual milk production, lactation stage, somatic cell count, age and sampling month and (b) the milk production response after anthelmintic treatment. There was a reasonable correlation between the mean individual and bulk-tank milk ELISA results (r=0.72). Individual cow ELISA results increased with higher lactation number and were lower in November than September. The associations with the other non-parasitic factors were weak and not significant. Milk yield responses to anthelmintic treatment were greater when treatment was given in early lactation and increased with the pre-treatment ELISA result and cow age. However, these latter two interaction terms were not significant when they were put in the model together. We conclude that (1) O. ostertagi ELISA results from individual milk samples may provide more information on the herd's parasitic status than a single bulk-tank milk result; (2) lactation number should be taken into account when interpreting ELISA results from individual milk samples and (3) the value of the O. ostertagi antibody level in individual cow milk samples to predict individual production responses after anthelmintic treatment remains equivocal.
authors.affiliation: Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium. johannes.charlier@ugent.be
authors.forename: Johannes
authors.initials: J
authors.lastname: Charlier
authors.forename: Jozef
authors.initials: J
authors.lastname: Vercruysse
authors.forename: Jonathan
authors.initials: J
authors.lastname: Smith
authors.forename: Raphaël
authors.initials: R
authors.lastname: Vanderstichel
authors.forename: Henrik
authors.initials: H
authors.lastname: Stryhn
authors.forename: Edwin
authors.initials: E
authors.lastname: Claerebout
authors.forename: Ian
authors.initials: I
authors.lastname: Dohoo
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D000909:Antibodies, Helminth / Q000032:analysis*; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007559:Ivermectin / Q000031:analogs & derivatives / Q000627:therapeutic use; D007774:Lactation; D008892:Milk / Q000276:immunology* / Q000378:metabolism; D010028:Ostertagia / Q000276:immunology; D010029:Ostertagiasis / Q000188:drug therapy / Q000453:epidemiology / Q000503:physiopathology / Q000662:veterinary*; D011897:Random Allocation; D016896:Treatment Outcome
chemical_list: D000871:Anthelmintics; D000909:Antibodies, Helminth; D007559:Ivermectin; C101434:eprinomectin