Dinitrochlorobenzene contact hypersensitivity as a marker trait for selection to improve disease resistance in calves.

Measurements of double skin fold thickness (mm) were used to assess the feasibility of use of cutaneous delayed-type hypersensitivity response as a marker trait to select for genetically improved disease resistance. Data were from a sample of 149 7-wk-old Holstein calves, from 15 sires, that previously had been sensitized to the contact allergen dinitrochlorobenzene. Response was monitored 24 and 48 h postchallenge. Analysis was by least squares according to a model that included fixed managerial effects, disease prevalence, and severity categories and sire of calf. Double skin fold thickness increased about 50% by 24 h, followed by a 4% decrease between 24 and 48 h. Season of birth was the only consistently significant fixed effect. Calves born in fall showed larger skin changes at each stage of response than calves born in spring. Restricted maximum likelihood estimates of paternal half-sib heritability were moderate to high for all stages of response, and phenotypic and genetic correlations between stages were significant and positive. Although the prevalence and severity of naturally occurring pneumonia and diarrhea did not significantly affect quantity of response, there is need to study further this relationship for intracellular pathogens. Delayed-type hypersensitivity response to dinitrochlorobenzene can meet requirements for a successful marker on which to base sire selection for disease resistance, if it is related to economically important, intracellularly characterized, pathogenic bovine diseases.