Danish Research Targets Sow Longevity

Bernie Peet is president of Pork Chain Consulting Ltd. of Lacombe, Alberta, and editor of Western Hog Journal. His columns will run every second week in the Manitoba Co-operator.

In my previous article, I explained how the Danish industry is improving productivity and reducing production costs through a focused research and development program which quickly delivers solutions to producers. The degree of co-operation and co-ordination in the industry ensures that challenges are promptly identified and addressed.

A good example of this is the research being carried out by the Pig Research Centre (PRC) on improving sow longevity. Sow mortality rates in Danish herds started to increase in the mid-’90s when average annual sow loss was seven to eight per cent. Between 1996 and 2006, it steadily increased to 15 per cent, where it remains today. The increased death loss has resulted in an average replacement rate of over 50 per cent, compared with 44 per cent in 1996. Some high-producing farms replace 60 per cent of their herd each year. In addition to the high economic cost of this, there are significant welfare implications.

Is the high level of mortality related to increased productivity and the resultant nutritional and physical burden on the sow? This is difficult to prove or disprove. The trend was established well before new genetic-selection techniques were introduced in 2003, which subsequently resulted in litter size increasing by half a pig per year.

We also know that Danish breeding stock, when used in other countries, does not appear to suffer from such a problem. That makes it more likely to be related to nutrition, health, housing conditions or management. A range of PRC projects have been examining a number of influences.


Shoulder lesions are a major source of sow death loss, especially because of strict laws on the transport of injured pigs which mean that affected sows have to be euthanized on the farm. Several projects have investigated both the extent of the problem and possible solutions. The use of soft rubber mats for sows that are showing signs of shoulder lesions has proved effective on some farms.

Increasing lactation feed intake through more frequent feeding may also help to maintain fat cover in the shoulder area and reduce the incidence of lesions. This is particularly effective when combined with good management of sow body condition, another area on which the project has focused.

PRC is also investigating whether it is possible to reduce shoulder lesions through breeding. It has recorded their incidence during the lactation period in nine herds, carrying out four or five assessments per sow. A total of 77,300 evaluations showed that if a shoulder lesion is defined as a lesion of minimum one cm in diameter, lesions were recorded in 20.1 per cent of the 17,091 lactation periods observed. The probability of a sow developing a shoulder lesion between her first and last parity was 27.1 per cent.

The information is being analyzed in order to calculate genetic parameters for shoulder lesions and the correlation with body condition, herd and season. If a reasonably high heritability for lesions is established, it will be possible to increase resistance to this problem through genetic selection.


Foot and leg problems are another major cause of sow loss through culling. Several PRC projects are looking at the causes of leg disorders and the impact of management and housing conditions during the gilt stage. Herd investigations revealed that the most common reasons for lameness were chronic changes in the joints, arthritis and hoof injuries. The veterinarians involved in the project concluded that very few cases of lameness were triggered by an infection and that treatment to relieve pain, rather than giving antibiotics, is most appropriate. Moving the most badly affected sows to a hospital pen also has a positive impact on recovery rate.

Now that most Danish farms use group sow housing, the introduction of gilts into groups during gestation is receiving considerable attention. Good introduction techniques can reduce the degree of injuries leading to lameness.

“These are often due to leg problems that are largely attributed to conflicts related to the formation of hierarchy that takes place within the first days in a new group,” says the PRC report. “Because of their low weight, gilts and young sows are the lowest ranking in a group of gestating sows.”

An ongoing trial on two farms is comparing how the type of group (stable or dynamic) and the social grouping (gilts and sows together and gilts only) impact survival until third parity. PRC has recently published a manual which outlines best-practice management for the management and handling of gilts which, it hopes, will contribute to improved sow longevity.


Putting all this research into practice is where the Danes gain the advantage over their competitors. Often, PRC uses commercial farms to implement its findings in association with advisers and veterinarians, such as in the ongoing “Sow Life” project. This involves 17 farms, all with high sow mortality. The pig advisers, veterinarians and PRC representatives visited the farms and specific advice was given to the pig producers on what to do on their farm to reduce mortality rates.

As might be expected, some farms were more successful than others in reducing sow mortality, however, on average it was improved and overall, gross margins increased.

“The systematic advisory process with joint visits from pig adviser and vet and with the participation of all key staff members of the farm proved very productive,” says the report.

Such “real life” demonstrations are extremely effective in conveying information to pork producers. Combined with regular publications and fact sheets, local information meetings, and a comprehensive website, they ensure that Danish producers stay ahead of the game and maintain their competitiveness.


bernie peet

Peet on Pigs


Reducingshoulder lesionsisone examplewhere resultsfromseveral projectsareshared withtheindustry.



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