Foot lameness remains a limiting factor in the productive ability of sheep. High levels of lameness are recorded in many sheep flocks and there is an acceptance of lameness amongst some sheep farmers in spite of the financial losses involved. It is now clear that lameness has a negative impact on the production level, fertility, longevity and welfare of individual sheep.
Recent UK data revealed that footrot is present in more than 90% of flocks and accounts for approximately 70% of lameness in sheep in England. However, although footrot is the most common cause of foot lameness in sheep, it is important to be aware of and to be able to recognise other lameness conditions. There are six common causes of lameness in sheep (see Table 1 and Fig. 1-3).
Occasionally mixed entities can occur, for instance footrot and CODD and as we understand more about the foot conditions affecting sheep it is now clear that several of these conditions are heavily interlinked.
For instance, the bacteria which causes footrot (Dichelobacter nodosus) is also responsible for scald and scald if left untreated will develop into footrot. As footrot and scald are now recognised as different manifestations of the same disease it is essential that both conditions are managed. Footrot is now also recognised as a major risk factor for the development of new CODD infections.
Costs of Lameness
A modelling system was recently used to estimate the financial impact of lame ewes in a flock with 10% lameness due to footrot. A flock of 100 ewes (Flock A), with 10% lameness, with no treatment or control measures was compared to a flock with similar incidence of foot rot (Flock B) with a simple control programme. In flock B, lame ewes were treated promptly with antibiotics and vaccinated against footrot twice yearly. In flock A the total cost per lame ewe was £14.16 due to the devastating effects of foot rot on the productive ability of the ewe. In contrast, the total cost of the control program, including medicine, labour and production losses in Flock B, with the same incidence of lameness, was only £5.54 per ewe, a reduction of £8.62 per ewe.
Losses were due to 15% reduction in conception rates, a 20% reduction in body condition score and a 20% reduction in lambing percentage in lame ewes. The impact however doesn’t end there as 20% more lambs born to lame ewes are estimated to be sold as stores instead of as valuable fat lambs.
Any lameness control plan must be tailored to suit the individual farm, the agents involved, the handling facilities and the environment. However, the following five point plan has been used successfully in many farms with footrot problems.
The five point plan
Three UK test farms initially implemented the five point plan to analyse its impact. All three farms reported significant challenges with lameness, primarily due to footrot and scald prior to implementation of the programme.
On these farms some improvements were made to the handling facilities, frequency of handling was reduced, a biannual footrot vaccination regime was introduced and up to 5% of ewes were culled for lameness in year one. All three farms achieved the target of less than 5% lameness within the first year of implementation and the farms that maintained their commitment to all five points of the Five Point Plan achieved lameness levels less than 1% in years two-four.
One farm which did not embrace all elements of the five point plan reported slightly higher lameness prevalence and more seasonal variation. This demonstrates that sheep lameness requires commitment to all elements of the Five Point Plan to achieve sustained lameness reduction. However, the success of these farms shows that lameness reduction is achievable within a relatively short time scale given the correct flock management.
It is clear to all in the sheep industry that lameness, particularly footrot, is a significant problem due to the devastating impact on the welfare of the affected sheep and also due to the substantial cost of disease on farm. The first step in the fight against lameness is to establish the number of sheep affected on farm; if more than 5% of sheep are affected then a control programme is needed.
The acceptance of high levels of lameness on farms has led to a vicious cycle of high disease challenge for ewes and lambs and continued lameness and loss of profit. However if control measures are adopted and tailored to suit individual farms then a prevalence of less than 2% lameness is highly achievable for the majority of flock owners.