Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 19, 2008
Publication Date: September 26, 2008
Citation: Casas, E., Snowder, G.D. 2008. A putative quantitative trait locus on chromosome 20 associated with bovine pathogenic disease incidence. Journal of Animal Science. 86:2455-2460. Interpretive Summary: This is a report of a putative quantitative trait locus on bovine chromosome 20, associated with incidence of multiple pathogenic diseases in cattle. Diseases under study were bovine respiratory disease (pneumonia), infectious keratoconjunctivitis (pinkeye), and infectious pododermatitis (footrot). It is likely that this region of bovine chromosome 20 harbors a gene that could potentially be involved in the regulation of the Major Histocompatibility Complex Class II. This complex is the immunological defense mechanism of livestock. This report, and reports of additional quantitative trait loci associated with other diseases in the same genomic region suggest that this quantitative trait locus is likely to be real. We propose that this is a quantitative trait loci related to the most costly diseases in cattle production. Health records may be useful to identify loci with consistent influence on the immune system.
Technical Abstract: The objective was to detect QTL associated with the incidence of multiple pathogenic diseases in offspring from half-sib bovine families. Four F1 sires were used to produce offspring: Brahman x Hereford (BH; n = 547), Piedmontese x Angus (PA; n = 209), Brahman x Angus (BA; n = 176), and Belgian Blue x MARC III (BM; n = 246). Treatment records for bovine respiratory disease, infectious keratoconjunctivitis (pinkeye), and infectious pododermatitis (footrot) were available for all the offspring from birth to slaughter. The incidences of these three microbial pathogenic diseases were combined into a single binary trait to represent an overall pathogenic disease incidence. Offspring diagnosed and treated for one or more of the previously mentioned pathogenic diseases were coded as a 1 for affected. Cattle with no treatment record were coded as 0 for healthy. Offspring inheriting the Hereford allele, in the family from the BH sire, and the Angus allele, in the family from the PA sire, were less susceptible to incidence of pathogenic diseases, when compared to those inheriting the Brahman allele and Piedmontese allele, from the BH and PA sires, respectively. A putative QTL for pathogenic disease incidence was detected in the family derived from the BH sire at the genome-wise suggestive level. This was supported by evidence, in the same chromosomal region, of a similar QTL on the family derived from the PA sire. The maximum F-statistic (F = 13.52; P = 0.0003) was located at centimorgan 18. The support interval of the QTL spanned from centimorgan 9 to centimorgan 28. Further studies should explore this QTL using other bovine populations to further confirm the QTL and refine the QTL support interval.