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Tail Lesions on Carcasses of Irish Slaughter Pigs

23 April 2015


Chronic tail biting appears to be a more common behaviour among Irish pigs than previously thought, according to Nienke van Staaveren and Laura Boyle in a recent newsletter from Teagasc.

The PIGWELFIND project aims to develop measurements of lesions related to pig health and welfare at the meat inspection process as tools for use by producers to help diagnose problems on farm.

As a research tool such ‘welfare lesions’ measured on the carcass can reduce the risk posed to biosecurity that is associated with farm visits. Furthermore, welfare lesions are often more visible on the carcass than on the live animal at the farm where conditions may be crowded, poorly lit and the animals are free to move away and may be dirty.

Work at Teagasc has focused on tail lesions which are an indication of welfare problems for pigs on farms and which are associated with abscesses and carcass condemnations.

Currently, much of the research focus elsewhere has been on outbreaks of severe tail biting and as such severe tail lesions are often the only tail damage recorded during meat inspection.

A survey of Dutch pig farmers showed that about 50 per cent of farmers reported no problems with tail biting on their farms and most considered tail biting severe when one animal had a tail wound, e.g. presence of blood. However, even moderate tail lesions can have welfare or economic implications and have been associated with a significant reduction in carcass weight of 1.2kg. This in combination with the losses due to carcass condemnation could lead to losses of up €1.69 per pig.

In this study, two factories were visited for three to four days and two researchers scored each carcass after scalding and de-hairing. Tail lesions for each pig in a batch were classified as none/mild, moderate or severe.

In total, 13,133 carcasses were inspected from 73 batches coming from 61 farms. Moderate and severe tail lesions were present in 25.2 per cent and 3.1 per cent of the pigs, respectively. The percentage of pigs affected with none/mild, moderate or severe tail lesions in a batch are shown in Table 1.

Table 1 shows that on average over a quarter of all pigs in a batch were affected by moderate tail lesions and results revealed that there is a lot of variation between batches.

Moderate tail lesions are associated with lower carcass weights and closer inspection of the data revealed that almost half of the batches had more than the average number of pigs affected by moderate tail lesions (i.e. 26.8 per cent).

Even more worryingly, almost 30 per cent of the batches had more than the average number of pigs affected by severe tail lesions, i.e. more than 3.4 per cent.

Table 1. Percentage ( per cent) of pigs affected by tail lesions in a batch
None/mild 69.9 20.0 96.0
Moderate 26.8 3.2 70.0
Severe 3.4 0 21.4

These data illustrate that tail biting is widespread on Irish farms but also that strategies or management plans are in operation on some units which seem to be successful in keeping the problem at bay. It will be important in the future to identify the reason for lower prevalence of tail lesions with different degrees of severity in certain farms.

The researchers found that of the 61 farms investigated 23 were keeping records in PigSys. Interestingly, these farms had a higher percentage of pigs affected with none or only mild tail lesions in a batch. They also had a lower percentage of pigs affected by moderate tail lesions in a batch but no difference was found for severe tail lesions.

Advisory services work to improve farm performance through better housing, management and nutrition of pigs. Record-keeping is a vital aspect of such services and the current work suggests that this could even have a positive effect on pig welfare. However, it could also be that farms that keep PigSys records have a different farm profile (e.g. herd size, number of stockpersons) which could have influenced the prevalence of tail lesions.

As mentioned, tail lesions are associated with reduced performance in the bitten pig, however this work did not take indirect costs at production level (reduced growth, medicines, labour etc.) into account.

Information from the PigSys database could help the researchers establish if there is a relationship between farm performance characteristics (e.g. days to slaughter) and the prevalence of tail lesions of different degrees of severity on that farm. This would lead to a better estimate of the cost implications of this production disease and to understand particular farm characteristics that might be risk factors for tail biting. The first farmers have been contacted to ask for permission to use their PigSys data for this purpose.

The high prevalence of moderate tail lesions in a high proportion of batches indicates that chronic tail biting is a much more common behaviour on farms than previously thought. The large variation between batches suggests that there is considerable room for improvement in the management of tail biting on Irish farms.

Given the economic and welfare implications of even moderate tail lesions it would benefit producers to receive information from the factory on such lesions recorded during the meat inspection process. This could help producers and advisors to keep track of tail biting on the farm and possibly intervene before chronic tail biting behaviour escalates into more severe outbreaks.

April 2015

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