The first step of the widely used ‘Dutch Method’ of cattle foot trimming is to trim the dorsal wall of the claw to 75 mm (2.95 inches), derived from the recommendations of Toussaint-Raven (1985) using average values deemed safe for Friesian cows 30 years ago. Other ‘experts’ have recommended trimming the dorsal wall to lengths ranging from 60 to 85 mm. One of the issues underlying these wide-ranging recommendations has been a clear definition of the external upper landmark from which dorsal wall length should be measured. Examples include the ‘proximal end of claw capsule’, the ‘distal edge of the periople’ or imprecise terms such as the coronary band or the coronet. Other issues have been varying recommendations about the appropriate shape of the trimmed toe and the target toe angle.
British researchers recently published the results of a study designed to derive recommendations for minimum dorsal wall length based on detailed analysis of the hoof anatomy of 68 Holstein-Friesian cows from a single herd. Internal structures of the hind claws were visualized using X-ray computed tomography (CT scan) as shown in the image below.
These images made it possible to measure the internal distance from the proximal (upper) limit of the wall horn to the distal (lower) tip of the dermis. A constant 14 mm was added to this measurement to allow for a minimum sole thickness of 5 mm, an average wall thickness of 8 mm and a toe angle of 50°.
Based on these measurements, the researchers classified the 219 claws examined according to the percentage for which various external dorsal wall lengths would have been adequate, measured from the proximal end of the perioptic horn. For example (see table below), an external dorsal wall length of less than or equal to 75 mm would have been adequate for only 5% of all claws examined; a length of ≤ 90 mm would have been appropriate for 100% of claws from cows less than 4 years of age and 95% of those from older cows.
|External dorsal wall length measured from proximal (upper) limit of external horn|
|Percentage of cows for which the external wall lengths above would be adequate|
|Cows < 4 years||4||52||98||100||100|
|Cows ≥ 4 years||3||17||66||95||100|
The authors of the study conclude: “Although this study was carried out on cows from a single farm, in the absence of larger studies to date, the authors propose that the minimum recommended claw length for any Holstein-Friesian adult dairy cow should be increased to at least 90 mm, measured from the proximal limit of wall horn, when trimming the toe to a point. Small reductions can be made for younger animals, for example, 85 mm would be appropriate for the majority of first- and second-lactation cows. If a step is left at the toe, the minimum recommended length should be 85 mm.”
The full research report is available here.