Project Overview
Commodities
- Animals: bovine
- Animal Products: dairy
Practices
- Animal Production: animal protection and health, genetics, livestock breeding, preventive practices
- Education and Training: extension, participatory research, workshop
- Sustainable Communities: quality of life
Proposal abstract:
Rationale: Lameness affects 36% of dairy cows in the US (USDA, 2016) and is associated with
reduced milk production and premature culling, raising welfare and economic concerns.
Lameness is often caused by claw lesions that manifest as open wounds in the soft tissue behind
the hoof, commonly foot warts (FW) and sole ulcers (SU). To enable genomic selection against
these conditions, the genomic regions that govern susceptibility to FW and SU must first be
identified.
Research question: What are the genomic regions associated with increased susceptibility to
FW and SU in dairy cattle?
Significance: Genomic regions identified in this study can be incorporated into selection indices,
allowing producers to select for cows genetically protected against FW and SU. These future
generations of healthier and more efficient cows will produce milk with a smaller environmental
footprint.
Methods: DNA from healthy and affected cows will be used in a genome wide association
(GWA) analysis for identification of chromosomal regions linked to case/control status. We will
use hoof scoring phenotypes and genotypes from the high-density single nucleotide
polymorphism (SNP) panel (800K SNPs) using FW n = 30, SU n = 30, controls n = 60. The
GWA will be performed using stratified allelic and pedigree-based association.
Expected outcomes: Because FW and SU are complex traits dictated by many loci (van der
Spek et al., 2015), stratified allelic and pedigree-based GWA analyses will likely reveal multiple
chromosomal regions associated with the affected status. Despite the different analyses, we
expect some of the chromosomal regions from the different analyses will agree, validating those
regions.
Outreach: We will communicate our findings directly with local producers at conferences and
vicariously through the extension team in the Animal Science Department at the University of
California, Davis. We will also share our findings through trade publications.
Project objectives from proposal:
The broad, long-term goal of this proposal is to reduce the incidence of lameness and
improve hoof health of Holstein dairy cattle. Thus, the objectives for this proposal are to:
1. Perform a genome wide association analysis to identify QTL regions contributing to
genetic susceptibility to FW and SU
Western SARE.
2. Utilize the the SNPs of largest effect to develop a predictive model to reduce
susceptibility to FW or SU that can be used in conjunction with the current selection tools
for milk production attributes to reduce the prevalence of FW and SU within a herd while
maintaining overall milk quantity and quality