Genetics Selection Evolution: genomic selection improves resistance to hoof disease

Approximately one in three dairy cows in the UK suffers from lameness. Reducing the prevalence of this disease is a key priority for the country's dairy industry .

Scientists from a number of UK universities conducted a genome-wide association search (GWAS) for a group of hoof diseases in Holsteins - hoof horn lesions (CHL), including sole hemorrhage (SH), sole ulcer (SU) and white line disease (WL ) . Quantitative trait candidate loci (QTLs) were identified on the BTA3 and BTA18 chromosomes for all traits under consideration.

Hoof horn lesions are complex traits with a polygenic type of inheritance. The heritability estimates for susceptibility to SH and SU (the likelihood that the animal will get sick) were 0.29 and 0.35, respectively. Estimates of heritability of severity (how severe the lesion would be if the animal got sick) were 0.12 and 0.07, respectively.

it turned out that the genetic correlation between SH and SU is high - 0.98 for the predisposition to the lesion and 0.59 for the severity of the lesion. The heritability of WL was found to be comparatively lower, meaning that the environment has a stronger influence on the development of white line disease than the other two diseases. However, the genetic correlations of SH and SU with WL were also positive.

In addition, CHL-associated candidate genomic regions have been found to contain annotated genes that are associated with immune system function and inflammatory responses, lipid metabolism, calcium ion activity, and neuronal excitability.

The scientists conclude that the incidence of lesions of the hoof horn is moderately heritable, and resistance to them can be increased using genomic selection. It should be noted that under different conditions, animals will show resistance in different ways, so it can be increased only on local assessments and when fixing disease phenotypes in their own enterprise.