According to a 2014 online questionnaire, lameness appears to be the number one health issue in Canadian dairy farms. On average, 5 to 7% of cows display severe lameness. The prevalence of subclinical lameness is much higher, as well as less severe hoof lesions that do not necessary cause lameness. Data recorded in Europe and North America shows 40 to 70% of cows in dairy herds have at least one type of hoof lesion. In Canada, almost 40% of cows presented to the hoof trimmer suffer from at least one type of hoof lesion. The more common lesion is digital dermatitis (20% of affected cows), followed by sole ulcer and white line lesions (7% and 5.4% of affected cows, respectively).

Data from hoof trimmers

To gain more insight in the prevalence of lameness, the condition was calculated based on data recorded directly by hoof trimmers in the provinces of Alberta, British Columbia and Ontario between 2009 and 2012. However, not all the cows that were in the herds during the trimming period were examined. The percentages of not-examined cows vary between herds, as the frequency of examination is different across them. Many of the not-examined cows are probably cows having no hoof lesions; this is because cows that show hoof problems are more likely to be preferentially sent for examination. Therefore, the prevalence reported is probably overestimated. It was shown that the prevalence of digital dermatitis decreases with lactation number (Figure 1).

On the contrary, horn lesions increase over parity. This increasing prevalence is more related to the decrease of the fatty cushion in thickness and quality as cows get older. Subclinical acidosis was envisaged before, but today experts believe that nutritional management in general is part of the explanation; this may be also due to the presence of irreversible hoof lesions, so that the prevalence accumulate with parity. Individual hoof lesions may represent a more precise measure of hoof health than the presence or absence of lameness itself. Moreover, the presence of a hoof lesion associated with pain will affect not only cows´ welfare, but also animal performance. It has widely been reported that cows affected by hoof lesions produce less milk, rest less by lying down, and have longer calving intervals. Therefore, the presence of hoof lesions represents an economic loss for dairy farmers, not only due to the costs associated with treating the lesions, but also the costs associated with decreased productive and reproductive performance.

Improving management practices

Management practices play a very important role in the development of hoof lesions. Different factors may influence hoof health, including type of floor and its condition (dry/wet, clean/dirty, presence/absence of adequate amount of bedding), nutrition and feeding management (low body scoring cows, overcrowding at feed bunk), as well the type of stall (e.g. higher prevalence of lesions in free-stalls than in tie-stalls). Very important is also the regularity of the trimmer session; it is recommended to trim hooves at least twice a year, ideally during the dry-off and again around 100 days in milk. Decreasing the incidence of hoof lesions can be achieved by improving management practices, but also through genetic selection. Under the same conditions, some cows will develop a lesion, and others will not. In the same way, some of the cows will recover more easily than others, and for some cows the same lesion will occur with a higher frequency or severity over the course of a single lactation. Selecting for resistance to hoof lesions could contribute to decrease their prevalence in dairy herds. Genetic improvement is permanent and desired gains cumulate through generations.

Data pipeline from hoof trimmers

Historically, a consistent selection for feet and leg conformation traits has not resulted in any decrease of hoof lesions. This is due to low genetic correlations between hoof lesions and type classification traits. Therefore we need to find alternative ways to select for more resistant cows, and hoof lesions need to be directly recorded. The objective of this large research project (part of Dairy Cluster 2) is to improve hoof health, by developing a data pipeline from hoof trimmers to Canadian DHI databank and to Canadian Dairy Network, and then to generate breeding values for sires. In order to create a national genetic evaluation system, a necessary step is to develop a data collection scheme that allows for the collection of reliable data in a univocal and consistent way. In order to achieve this goal, collaborative work with hoof trimmers is essential. Hoof trimmers willing to share data have been identified across Canada, and a standard protocol on which data and traits are collected has been developed. The Hoof Supervisor® system (hereafter named ´the system´) (KS Dairy Consulting Wisconsin, USA) has been selected as the electronic device to be used in the project. The software has been adapted to include the permanent cow identification number and DHI herd number, and it is now available in a French and in an English version.

Selecting for hoof health parameters

In Quebec, a pilot group of trimmers has successfully tested the exchange system of files and now, a group of 26 trimmers just started the collection of data in June. Once the system will run smoothly, trimmers across Canada using the system will get on board. Hoof lesions previously recorded with the system in Alberta, British Columbia and Ontario have been analysed in order to evaluate the possibility to use this type of data for selection purposes. Obtained results were promising (Table 1), despite the fact that the volume of data needs to increase in order to allow validation. Despite the low heritability of hoof health traits, the EBVs showed variability between sires, and higher EBVs were observed for sire with lower prevalence of affected daughters, opening the possibility for selecting on the base of hoof health parameters. These promising data show that genetic evaluation will have a real impact on improving hoof health in dairy herds. Along with good management practices, genetic selection will soon be included in the toolbox available for dairy managers looking to improve the hoof health status in their herd.

Table 1 - Percentage of daughters with hoof lesions from all (average),

the best (10% quantile) and worst (90%quantile) sires according to

their EBV for resistance to digital dermatitis, sole ulcer and interdigital hyperplasia.

*Only sires with at least 50 daughters were considered (N = 182)

This project is funded by the Dairy Research Cluster Initiative (Dairy Farmers of Canada, Agriculture and Agri-Food Canada, the Canadian Dairy Network and the Canadian Dairy Commission), the Ontario Genomics Institute, and Alberta Milk.

Francesca Malchiodi, Anne-Marie Christen and Filippo Miglior, CGIL

University of Guelph, Valacta and Canadian Dairy Network

Source: dairyglobal.net