Abstract

Hereford cattle have a dominantly inherited white face that is characteristic of their breed. A small proportion of Hereford cattle present with regions of pigmentation around the eyes, known as ambilateral circumocular pigmentation (ACOP), which is hypothesised to provide UV-protectant properties to the underlying tissue. ACOP has been associated with reduced incidence of two diseases, bovine ocular squamous cell carcinoma, and bovine infectious keratoconjunctivitis, making it a desirable trait for selection. We conducted a genome-wide association study for ACOP in 605 American Hereford cattle using 43,789 genetic markers, and investigated the phenotypic association between face-colour and ACOP. The most highly associated variant from our genome-wide association study mapped to Chr6 g.71059814G>A and explains most of the variation for this trait. This variant falls in close proximity to the well-known coat-colour patterning gene KIT, suggesting it may be the causal gene for this trait. Our results suggest that ACOP is not directly influenced by face-colour, and may be influenced by non-additive genetic effects. These results provide an opportunity to select for Hereford cattle with ACOP, enhancing welfare, and reducing the incidence of bovine infectious keratoconjunctivitis and bovine ocular squamous-cell carcinoma. Keywords: Hereford cattle; ambilateral circumocular pigmentation; ocular squamous cell carcinoma; infectious keratoconjunctivitis; GWAS; pigmentation traits

S, Jivanjia, T Koscha, M Littlejohn, and DJ Garrick

New Zealand Journal of Animal Science and Production, Volume 81, Online, 39-44, 2021