Castration: Is It Necessary?

Welfare issues relating to pig production have become very topical in Europe. Consumers are increasingly critical of production methods, and there is growing concern about castration and the pain and stress it causes to the pig.

Organizations such as Compassion in World Farming, the U.K."s Royal Society for the Prevention of Cruelty to Animals and People for The Ethical Treatment of Animals have high-profile celebrity members, are very powerful and have effective publicity machines that lobby Eurocrats and draw the public's attention to animal-welfare issues. Such organizations were instrumental in getting sow stalls banned in the United Kingdom. Currently these bodies look at all aspects of pig production and target any that they claim reduce a pig's quality of life, such as castration. 

Of course, there are practical management problems associated with rearing intact (non-castrated) hogs in a group, but the major problem is taint/odor in the meat. Boar taint's main component is a derivative of the male sex pheromone androstenone, and it gives the meat a smell of stale urine. Skatole and indole also are related to boar taint. Both are found in pork from gilts and barrows but in lower concentrations than in intact boars.

Women are more sensitive to these substances, which tend to volatilize when the pork is cooked. The problem is compounded by the fact that women still do most of the cooking in European households. The Danes ship massive amounts of pigmeat to Asia, competing with the United States and Canada. Asians are particularly sensitive to odorous pork, and so the Danes will want to hold on to castration as they cannot afford to risk losing this export market.

The U.K. Situation

The U.K."s Meat and Livestock Commission carried out much research in the 1990s to look at pigmeat from intact boars. MLC concluded that at the U.K."s common slaughter weight of about 90 kg live, taint was not a problem. This meant that pigs reached slaughter weight before becoming sexually mature and before boars started to produce androstenone. U.K. slaughter weights have gradually risen over the last 19 years, but so have growth rates. All U.K. quality-assurance schemes specify that males remain uncastrated, a "welfare" point that MLC and big U.K. supermarket chains promote to the public.

There are production benefits of raising intact boars, as is noted in the accompanying sidebar. As the data shows, intact boars have a much better feed conversion, live-weight gain and leaner carcasses. These benefits outweigh the slightly poorer dressing percentage, which is due to the testes being cut out after slaughter and not included in the carcass weight.

Not without Problems

Certainly when intact males are reared together commercially as in the United Kingdom, "riding" by the more aggressive pigs in the group is common, which means all pigs have to be evenly sized. Small male pigs get picked on and are ridden continuously by pen mates causing much distress, such that the afflicted pigs must be removed from the pen.

Split-sexing the pigs means that the diets can be adjusted accordingly. Initially in the United Kingdom, diet specification for intact males did not meet their growth potential, which resulted in ultra-lean carcasses. Lysine and energy levels had to be increased to ensure more normal fat depths.

When non-castration was in its infancy in the United Kingdom, one major slaughterhouse still had concerns over boar taint and carried out carcass checks called the "hot wire" test. As the name implies, a hot wire was inserted into the carcass to melt a small amount of backfat. If the test produced malodours, the carcass was diverted and used for manufactured pork products. Once the packer was satisfied that taint was not a problem, the practice was discontinued.

On average, mainland Europe, and certainly the United States, slaughter pigs at much higher weights than the United Kingdom, which would then carry more risk of taint. So other European industries are resisting castration bans. The Italians, in particular, would reject anything that might affect their prestigious Parma ham trade.

Options and Developments

In 1998, an Australian company, Commonwealth Serum Laboratories based in Victoria, launched Improvac, a boar taint vaccine for male pigs. It is a vaccine against gonadotrophin releasing factor (GnRF). Testes function is driven by GnRF, and Improvac stimulates the pig's immune system to produce specific antibodies against GnRF that inhibit testes function and minimize androstenone and skatole production. The vaccine involves two, 2-ml injections. The first is given eight weeks before slaughter, the second four weeks prior.

Pfizer Animal Health now markets Improvac, which is being used in Australia, New Zealand, Costa Rica, Mexico and Brazil. The vaccine also was launched 12 months ago in the Philippines. Pfizer officials emphasize that the product is not a hormone or drug and, like other vaccines used to prevent disease, does not have any meat-withdrawal issues.

In Norway, since 2002, only veterinarians have been allowed to castrate piglets. Castration was to be banned completely as of January 2009, but that deadline has
been deferred.

As of March 1, all piglets in the Netherlands must be castrated under anaesthetic; otherwise, the pork is not allowed to enter the food chain. Dutch equipment  company Schippers sells its "MS Pigsleeper" anaesthesia equipment to producers for $1,450. This on-farm device incorporates "traffic lights" which switch from red to green once the piglet has become anaesthetized, using CO2 gas. The Swiss are using a similar device with piglets being anaesthetized with isoflurane, under veterinary
supervision. Castration without anaesthesia will be banned there by 2010.

As for Denmark, in July 2008 the Danish Animal Welfare Council recommended that from Jan. 1, 2010, it should be compulsory for piglets to receive pain relief for castration versus anaesthesia. In the longer term, Denmark is committed to phasing out castration. The Danish Meat Association and the Danish Meat Research Institute are working on an electronic "nose" to detect off-odors and taint, but that technology will not be ready for commercial use anytime soon.

Selection for breeds or lines low in skatole and androstenone levels or developing DNA markers are other options. Sexed semen could resolve this problem by producing litters of gilts. Ovasort, a Welsh company, together with Dansk Svineproduktion, are working on developing low-cost, high-volume sperm separation, using flow cytometry technology. There are too many variables to get 100 percent separation, but 90 percent should be possible. 

Since 2006, the E.U."s Sixth Framework program has funded a $31 billion, four-year, cross-European project called SABRE, involving 30 animal-breeding research groups and businesses across 14 countries. The project is wide ranging, but a key area is to eliminate boar taint in pigmeat. It will be interesting to see the project's eventual results.

Benefits of Intact Pigs

Not having to castrate male pigs has many benefits for the producer, not least of which is the time saved, but also the reduction in stress for the hog and stockperson. Other production benefits are listed here, with castrates = 100 percent, and the intact male pigs in commercial settings as:

Live-weight daily gain                   103%

Live-weight gain/feed                   113%

Dressing percentage                     99%

Carcass-weight daily gain           102%

Carcass lean percentage            106%

Lean-weight daily gain                  116%

Lean-weight/feed                           131%

Source: Kempster T, MLC (1994)