A genetic evaluation tool for Hoof Health is now available for the Holstein breed. The tool promotes increased resistance to eight key foot lesions.
The selection for Hoof Health index was made possible through a research project financed under the Dairy Research Cluster 2 (a partnership between Dairy Farmers of Canada, Agriculture and Agri-Food Canada and the Canadian Dairy Network (CDN)) that spanned from 2014 to 2017, targeted at improving hoof health in Canadian dairy herds. After only one year since the project’s completion, CDN is able to transfer the research to the field with genetic evaluations for Hoof Health.
Two other key outcomes from the research project were also delivered. The first is the development of a data collection pipeline from hoof trimmers, to Canadian DHI, and then on to CDN, where it is stored in a national database. The second outcome includes the development of an interactive DHI hoof health management report, which will be available to dairy farmers in the coming months.
From Genetic Evaluations for Digital Dermatitis to an Overall Hoof Health Index
Genetic selection for increased resistance to Digital Dermatitis has been possible since December 2017. The new Hoof Health (HH) evaluation will replace Digital Dermatitis as the primary selection tool – a logical transition since Digital Dermatitis is one of the eight lesions that make up the Hoof Health index. The full list of lesions included in Hoof Health are included in Table 1. The frequency of Digital Dermatitis is the highest among the eight lesions, at approximately 17%. Of cows presented to the hoof trimmer, 46% experience at least one hoof lesion in their lifetime.
|Table 1: Frequencies, Heritabilities, Correlations and RBV Translation for the Eight Hoof Lesions Included in the Hoof Health index|
|Lesion||Frequency (%)||Heritability (%)||Correlation with Hoof Health index (%)||Expected % increase in Healthy Daughters for each 5 point increase in Hoof Health|
|Heel Horn Erosion||2.9||8||76||0.1|
|White Line Lesion||4.7||4||9||1.4|
The heritability of each individual lesion is included in Table 1, ranging from 3% to 8%. The heritability of the overall Hoof Health index is 9%, meaning 9% of the variation for hoof lesions seen in Holsteins can be attributed to genetics. Correlations of the individual lesions with the overall Hoof Health index are also presented in Table 1. Infectious lesions like Digital Dermatitis, Interdigital Dermatitis and Heel Horn Erosion have high correlations with Hoof Health. The correlations between Hoof Health and the non-infectious lesions like Sole Ulcer, Toe Ulcer, White Line Lesion, Sole Hemorrhage and Interdigital Hyperplasia are more variable. Toe Ulcer and White Line Lesion have the lowest correlations with Hoof Health since they each have a small negative genetic correlation with the three infectious hoof lesions.
Overall, the correlation between Hoof Health and both the Lifetime Profit Index and Pro$ is 58%, meaning selection for either national index will result in improvement for Hoof Health.
In the coming months, a separate Relative Breeding Value for each of the eight lesions will appear on the CDN website when selecting the “Health” tab for any Holstein sire.
For a copy of the full article, you can download it here: Genetic Selection for Improved Hoof Health is Now Possible!