Can scanning reduce shoulder sores?
Monitoring of shoulder sores on sows in Denmark has raised the question of whether to use fat measurements to identify sows at risk
In the spring and summer of 2007, pig producers in Denmark were subjected to a new wave of attention from politicians and the media in connection with the problem of shoulder sores in sows. The question this has raised is whether we are on the right track for dealing with the sow injuries problem.
The debate over shoulder sores affecting sows from their time spent in farrowing pens is just part of the wider public pressure on the Danish pig industry over animal welfare. A requirement for abattoirs to record these injuries in sows sent for slaughter has existed since 2001. As from 2003, the most severe cases seen either at the slaughterhouse or on the farm by the veterinary adviser must be reported to the police.
We can say now that the last 4 years have been a time of intensive focus on sow sores in our country. Back in 2003 the forerunner of national technical organisation Dansk Svineproduktion (DSP) declared that a period of sustained testing and advice to producers had resulted in a decreased number of shoulder lesions in Danish sows. The organisation concluded that the way to reduce these injuries was by good management. It recommended immediate action at the first signs of reddening of the skin and the culling of any sows that displayed unmistakeable shoulder sores after farrowing. Checking backfat thickness was also mentioned because of evidence of a possible link between the sow's body condition and injuries to her shoulders from contact with the floor or equipment.
Later that same year it published records from 3 Danish slaughterhouses for sows inspected over the previous 36 months. These showed a seasonal variation, with more sore-wound injuries seen in summer. Their incidence also varied from one slaughterhouse to another, but 2 of the abattoirs had registered an increasing number of remarks regarding shoulder sores during the review period of 3 years.
An important conclusion was that 3 times as many shoulder sores were found by checks of live animals on receipt at the slaughterhouse compared to the number detected after slaughter by meat control. Whereas the meat control procedure identified the presence of lesions in 2.7% of the sows, the live check of the same sows detected sores in 10% of them.
Although subsequent years brought a reduction in cases, the start of 2007 saw reports of increased notifications of shoulder sores on sows delivered to the slaughterhouses. DSP said the sores could be difficult to detect on the farm. Quite often, they became visible only after slaughter when the carcase went through scalding, dehairing and veterinary inspection. Herds were suggested to seek the help of their veterinary adviser in checking the sows. However, this extra control on the farm was still to be based on the animal's external appearance.
What can producers do? Dansk Svineproduktion has published guidelines for producers in the form of a Ten-Point Plan on how to reduce the incidence of shoulder sores in sows. It is shown in the accompanying panel, which uses the organisation's own translation of the original Danish. In the light of recent events, did the plan introduce new knowledge or is it even the right tool for preventing the problem? The possibility must be faced that the research done so far may not have been good enough or that the results have not been communicated adequately to the operators of sow herds.
The first advisory manual on shoulder sores in sows went out to producers in 2005. In it were remarks about feed curves, the adjustment of rails on the farrowing crate, the type of flooring and giving sows a material for their rooting behaviour. The case for culling of sows with a history of shoulder ulcers was discussed. Treatment of inflamed wounds might require antibiotics. For at-risk sows, the recommendation was to provide them with a rubber mat or other kind of soft bed, alternatively they and their litters could be moved to a pen with deep litter.
The floor surface for farrowing has long been among the farm facilities proposed as a risk factor. The first tests of using a rubber mat in the sow's area of a fully-slatted farrowing pen were carried out in 2004. No rubber mats designed specifically for pigs could be obtained at that time, so the pilot project started with cattle mats. The conclusion afterwards was that the use of a rubber mat should be considered only as a supplement to management changes aimed at prevention and also to responses such as the culling of affected sows.
The middle months of 2006 found a DSP bulletin to producers stressing the importance of prevention. The number of shoulder sores was lower than it had been for many years and rubber mats had played an important part in this. A soft bed of some form was being called a good precaution if provided early enough to any sow in the risk group, but there were doubts whether it should be obligatory for all sows because shoulder sores affected only a minority.
Mats show sows at risk
The official line remains that mats should be used when a problem arises. However, part of their benefit may be that they signal which sows are at risk to the people who attend to the farrowings. It could be the extra attention given to the sow that makes the difference, in which case perhaps we should mark at-risk sows to ensure they receive all the extra care they need. The same logic argues against placing rubber mats in all farrowing pens, on the basis that this would simply remove the visual marker identifying particular sows with problems.
The central issue is how to identify the sows that are at risk. Calculations in Denmark in 2004 had shown an average at the time of 8% of sows per farm with damaged shoulders. The percentage varied considerately from farm to farm, however, with some units registering only 1% and the worst having 22%. The sows most at risk were the older members of the herd and those with a low score for their body condition or showing mobility problems.
Body condition has been spotlighted repeatedly as a risk factor, so I wonder if a scanner to measure fat depth would not be a better investment than mats for all the sows. Danish advice put forward at the end of 2004 had advocated assessing condition objectively by measuring the thickness of the sow's backfat. It was found that, statistically, sows with a fat depth of less than 16 millimetres were certain to develop shoulder sores. Therefore herds were advised to make sure their sows had at least 18mm of fat cover by farrowing time.
A later manual also referred to body condition score as well as the need to avoid weight loss. It talked about fat thickness, stating that this must not be outside the range of 15-22mm. In fact the minimum related to the risk of sores on shoulders, but the upper limit was linked more to possible problems of MMA-mastitis and sows being overweight.
To spot the sows at risk of developing shoulder sores, producers have been told to look especially at animals scoring badly on body condition, those with a previous history of suffering shoulder sores and animals with a tendency to leg problems. Together with weight loss during nursing, these factors should set off alarm bells by the people looking after the sows.
However, in my opinion the advice has failed to emphasise strongly enough how important fat measurement is as a tool for estimating if the sow will be able to avoid shoulder lesions while nursing her piglets. Extra attention must be given to sows in the risk group. Measuring their fat depth enables the producer to pick them out before they farrow — not after farrowing. PIGI