Update on the costs of sole ulcers through a review of the recent literature

The costs of lameness were reported by Willshire and Bell (2009), but input costs have changed substantially and there are more reports of performance losses associated with different stages of disease. The following is a concise summary of some of the scientific literature from Nick Bell, with contributions from James Wilson and review from Sara Pedersen.

Defining a sole ulcer

The sole ulcer is defined as the classic ulceration in the “typical site” which sits midline and axially in zone 4 (Figure 1) and almost always in the lateral hind claws or medial fore claws. When recording it is important we differentiate these lesions from heel ulcers (more commonly found in the medial hind claw and referred to by trimmers as sole fractures or heel fractures) which run from the zone 4 margin into zone 6, a toe ulcer in zone 5, axial wall fissures in zone 1 (running into 5), and white line lesions in zone 1-3.

Figure 1: Hoofmap zones (taken from the AHDB App, to be launch this year). Sole ulcers are found in zone 4 at the point marked with a red X, axial of midline.

Milk Yield depression

Milk yield accounts for a substantial component of estimated performance losses in most studies. In a Spanish study involving 804 herds and 108,468 trimmings Charfeddine and Pérez-Cabal (2017) identified a yield reduction of 65kg per day and 120kg over 2 months for mild/severe lesions respectively. This is somewhat lower than the 570kg milk reported by Amory et al (2008) study which might be for a few reasons. Firstly, milk yield depression appears to start 4 months prior to a lameness event and can persist for 5 months afterwards (Green et al 2002) so the Amory et al (2008) study captured a longer period of milk loss. Secondly, Amory et al (2008) reported farmer treatments whereas the Spanish study used trimmer reports and so the severity of lesion is likely to be milder in the Spanish study and the efficacy of treatment superior with using professional trimmers, particularly if following best practice treatment protocols are adopted (see later). Lastly, Amory et al (2008) considered milk yield vs expected, as higher yielding cows were more likely to go lame, with yields regressing to the average.

Randall et al (2016) identified a reduction of an average 2.68kg milk per day in heifers with sole ulcers, and this included both a reduction in daily milk yield, and a reduced amount of time spent in the herd (reduced by 326 days). Cha et al (2010) estimated milk yield losses based on work by Warnick et al (2001) to be around $83 (approximately £55 in sterling) while a large Spanish study (Charfeddine and Perez 2017) found a similar milk yield loss of between $42.4-98.6. However, we still consider the Amory et al (2007) estimate which reported 570 litres lost per lactation as most robust and representative of most UK herds.

Fertility

In the Willshire and Bell (2009) partial budget the cost per day open was calculated. Hudson et al (2015) used models to estimate a cost of £5.50 per day open which is liley to be even higher with current input costs and milk price. When accounting for costs of disease it is important to minimise risk of double accounting by focussing on the primary disease to be managed – in this case primary lameness leading to secondary infertility, and not vice versa.

Charfeddine and Pérez-Cabal (2017)  identified that animals with mild and severe sole ulcers would have an increased calving to first service interval (+5 and +8 days respectively). However, looking at days open, they reported +1.6-17 days in cows with sole ulcers, and so we took the midrange of this figure. This is substantially lower than the 40 days extension to calving interval reported by Lucey, but similar to Collick (1989) and Fourichion et al (2000). All these studies have varied slightly in the period they have evaluated fertility impact in relation to lesion presence which inevitably accounts for some difference. Modern day fertility programmes are likely to account for better management of infertility in lame cows. Remnant et al. (2019) found a minimal effect of lameness on fertility performance, but that may be due to the nature of the farm records being used within that study. Overall the cost of infertility is substantially lower the previous estimates and may reflect better fertility management options for lame cows.

Culling

Charfeddine and Pérez-Cabal (2017) identified a reduced productive life effect in 1^st lactation with both mild and severe lesions (-38 and -59 days respectively). We took the mid-range of this figure (48.5 day) for our revised estimates and applied across all cases regardless of parity. Randall et al. (2016) identified that heifers would be in the herd for 326 days fewer if they had hoof lesions in early lactation (Randall et al. 2016). An unpublished study based on 4 herds in Dorset found a cow with a recorded sole ulcer survived 457 days less in the herd, but all these herds operated a proactive culling policy. However, both these other studies shows 48.5 days less in the herd is a relatively conservative figure for earlier culling.

Treatment Costs

Current market value of a trim for all four feet is anywhere between £8-15, but most farms would be able to deliver in house trimming at £4 per cow. Many trimmers still charge £10 per trim and so we opted for this value. Blocks tend to cost in the region of £7-12 per application. A course of ketoprofen cost £33 (based on cost of ketoprofen from Farmacy, dosing at 3days of 20ml per cow). Cha et al (2010) gave SU treatment costs to be around £40 which looks an underestimate according to our data but may be more reflective of common practice of not giving NSAIDS. Giving NSAIDs might reduce some impact of losses reported in other studies (milk yield, culling and infertility). Our revised figure in 2022 would be £59.74 per treatment which includes a repeat treatment rate of 12% (Barker 2007).

Table 1: Cost calculator for sole ulcer (cost budget method)

Overall sole ulcer cost

Our revised estimate of £582.72 per lactation for a cow case of sole ulcer cost is 12% higher than the previous estimate from Willshire and Bell (2009) reflecting an increase in input costs, increased milk price, a change to the calculation method and a downward revision of some performance impacts. Dolecheck et al (2019) used stochastic modelling techniques to estimate costs/losses to be between $116 ± £33 (£86 ± £24.50 today) and $282 ± 56 (£209 ± £41.50) with a mean of $178 ± 29 (£132 ± £21.50) using US input costs. This is somewhat lower than the figures reported here but the US authors commented that the input costs were lower for their US models compared with Willshire and Bell (2009).

The cost of lost milk revenue and premature culling account for most of the cost. The cost of culling is a complex calculation with large degrees of uncertainty attached to it linked to pressures to cull for other diseases, genetic selection, carbon efficiency and longevity targets set by industry. Further work is needed to refine models for these estimates.

Note there are many generalisations with estimating performances losses, and when translating these to on-farm estimates, recoverable losses must be estimated using “best case scenarios” and “average outcomes”, not complete disease control or elimination of all disease cost which is unrealistic.