Castration

The majority of all male pigs in Denmark are castrated to prevent boar taint in meat from these pigs. In 2009, pain relief was introduced as a requirement during castration of all male pigs in Denmark. Initially, this was a requirement under the DANISH Product Standard concept that was later made statutory. Pain relief injected in the neck of the pig lasts approximately 24 hours.

European scientists are searching for suitable methods for anaesthetising piglets during castration. However, so far, they have not found any applicable methods, i.e. methods that are practical, safe for humans and animals and have a documented positive effect on piglet welfare.

Several trial activities with male pigs are in the pipeline

Politics

In Europe, it is agreed to stop castration by 2018, and this is the time frame we are working with.

For Danish pig producers to stop castrating male piglets, we need to have an online method to ensure that our customers are not offered pork with boar taint. It is also essential that the method and acceptance limits are accepted by the consumers.

Boar Taint

Boar taint is primarily attributed to two substances: skatole, which is produced in the intestines, and androstenone, which is produced in the testicles. Both substances are metabolised and decomposed in the liver. The fractions that are not decomposed in the liver are deposited in fatty tissues.

Boar taint is particular distinct when meat is prepared, but not all are able to smell it. In 1980s and 1990s, Danish scientists developed online equipment for recording skatole. At the time, slaughter weight was lower than today, and skatole was then the documented predominant cause of boar taint. Consequently, in order to keep producing male pigs that are increasingly heavy, future analysis equipment must be able to detect skatole as well as androstenone.

Trials with male pigs

PRC is currently focusing on:

• cost-benefit, male pig production
• effect of feeding on boar taint
• development of boar taint with age and weight, and
• breeding against boar taint

Economy

When a pig producer delivers a male pig for slaughter, DKK25 is deducted from the price to cover skatole analyses etc. A male pig is only approved when skatole levels in fat are below 0.25ppm. If a male pig is rejected, DKK2 is deducted per kilo of carcass weight.

New cost-benefit analyses reveal that compared with production of castrates, profits range between DKK7 and DKK29 per male pig after male pig deduction (none rejected) with liquid feeding and dry feeding ad lib, respectively. Profits drop by approximately DKK1.50 per pig when rejections increase by one percentage point (August 2012).

The project was financially supported by the EU and the Rural District Programme under the Danish Ministry of Food, Agriculture and Fisheries.

Chicory field

Feeding

Fermentable carbohydrates influence fermentation processes in colon and thereby the production of skatole.

Research revealed that the addition of 15 per cent chicory to feed for two weeks before slaughter reduced skatole levels but did not affect androstenone levels in male pig fat. However, chicory is currently too expensive to use in pig feed.

Research, therefore, continues to find feeding strategies that may reduce skatole in fat.

Androstenone is influenced by maturity, and will therefore not be affected by changes in feed.

Several trial activities with male pigs are in the pipeline.

Age/slaughter weight

Preliminary research demonstrates that when slaughter weight increases from 75 to 95kg, androstenone increased but skatole remained unaffected.

Improvac

In cooperation with Pfizer, the effect of immuno-castration was investigated. Results demonstrated that immuno-castrated male pigs grew faster and had better FCR and lean meat percentage than castrates, and were actually performing at the same level as female pigs. No male pigs were rejected due to skatole but a taste panel found that vaccinated male pigs excreted more boar taint than castrates (IPVS 2012). Though approved for use, Improvac is not used in Denmark as Danish slaughterhouses refuse to receive vaccinated male pigs.

The future

PRC will continue to research for ways to reduce boar taint in cooperation with research institutes and universities. In addition, several of our external collaborators are working on detection and development of online analysis methods.

August 2013