|Title||Genetic background of claw health in dairy cattle|
|Author(s)||Spek, D. van der|
|Source||Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Henk Bovenhuis. - Wageningen : Wageningen University - ISBN 9789462573475 - 158|
Animal Breeding and Genomics
|Publication type||Dissertation, internally prepared|
|Keyword(s)||melkvee - klauwen - diergezondheid - voetziekten - genetische parameters - heritability - genomica - selectief fokken - dierveredeling - dairy cattle - claws - animal health - foot diseases - genetic parameters - heritability - genomics - selective breeding - animal breeding|
|Categories||Cattle / Animal Breeding and Genetics (General)|
Van der Spek, D. (2015). Genetic background of claw health in dairy cattle. PhD thesis, Wageningen University, the Netherlands.
Claw disorders affect cow welfare and profitability of farms and as such are important traits relevant to dairy cattle breeding. Aim of this thesis was to increase our understanding of the genetic background of claw disorders to enable selection for reduced claw disorder incidence. The claw disorders were: abscess, corkscrew claw, (inter-)digital dermatitis or heel erosion (DER), double sole (DS), hardship groove, interdigital hyperplasia (IH), interdigital phlegmon, sand crack, super-foul, sole hemorrhage (SH), sole injury, sole ulcer (SU), white line separation (WLS), and yellow discoloration of the sole. Data was collected on Holstein cows kept in dairy herds in France. Individual claw disorder frequencies ranged from 0.1% to 23.8% and more than half of the trimmed cows had at least one claw disorder in at least one hind leg between 2007 and 2012. Heritabilities were estimated for DER, DS, IH, SH, SU, and WLS, and ranged from 0.02 to 0.14. Repeatabilities ranged from 0.02 to 0.33. The need for trimming (“trimming status”) was found to be heritable as well with a heritability of 0.09. A high need for trimming the claws of cows is unfavorable and therefore trimming status is an interesting trait to include in genetic evaluation. Most claw health traits had similar heritabilities and were genetically the same trait in different parities, lactation stages and herds with different trait frequencies. Claw disorder frequency in Montbeliarde cows ranged from 9.4% to 41.1% and 73% of the cows had at least one claw disorder in at least one hind leg between 2007 and 2013. Heritabilities ranged from 0.01 to 0.09. Heritability for trimming status was 0.06, confirming that trimming status is a heritable trait.
To identify genomic regions associated with claw disorders and trimming status, a genome wide association study was performed. In total, 11 significant and 46 suggestive SNP were detected. Three of the suggestive SNP could be validated using a dataset of genotyped bulls. The detected SNP were spread across the genome and a major gene was not found.
In the general discussion, alternative ways of measuring claw disorders were discussed. Accuracy of progeny testing and genomic selection for claw disorders was compared and a breeding program to reduce claw disorders was simulated in order to estimate selection response. Reducing the incidence of claw disorders is achievable with selection, but at a cost of a decrease in production.