Strategies for Control of Boar Taint

Summarised by swine grower/finisher specialist of OMAFRA, Doug Richards, this paper was presented by Dr Jim Squires at the University of Guelph at the Centralia Swine Research Update on 28 January 2009. Dr Squires outlined the relative merits of three methods of controlling boar taint: nutrition, immunocastration and genetic selection.

22 April 2009

4 minute read

Young male piglets are castrated to prevent off-odours and off-flavours (boar taint) in the meat at slaughter weight. Boar taint is caused by the accumulation of two compounds, androstenone and skatole in the fat.

Intact boars have improved feed efficiency, nitrogen retention and lean gain compared to castrates, which could result in significant economic gains to producers.

Intact Males
Decrease in feed intake	-12%
Decrease in feed:gain	-12%
Increase in lean yield	6.50%
Decrease in dressing percantage	-1.50%
Increase in gross margin*	36%*
* costing on 1995 prices, current feed prices will give greater returns

There are also growing animal welfare concerns leading to some EU countries banning surgical castration in the next few years even with anaesthetic. Recently some major stores in the Netherlands have stopped selling pork from castrates. Controlling boar taint without surgical castration would have dramatic benefits for production and consumer acceptance of pork products.

Options for Control of Taint

Nutrition

Boar taint from skatole is affected by diet and the environment. Skatole levels can be decreased using fermentable carbohydrates in the diet. Skatole can also be absorbed from manure, so dirty pigs of any sex can accumulate high skatole levels in the fat. Androstenone levels are affected by sexual maturity and slaughter at much lighter weights (before puberty) is not economical. Diet is not an effective solution for boar taint.

Immunocastration

Immunocastration works by injecting a vaccine that stimulates production of antibodies that shut down testicular development to the same extent as surgical castration. The vaccine is given to boars near slaughter weight so they grow as normal boars for most of their lives. The vaccination reduces boar taint to levels found in castrates, reduces aggression and sexual activity, increases feed intake and improves growth rate, improves feed efficiency compared to castrates and lean yield is intermediate between boars and castrates.

A commercial vaccine (Improvac) is currently under regulatory review.

Genetic selection

Genetics can affect the amount of boar taint within a breed and between breeds. The University of Guelph has developed genetic markers for boar taint. They have a database of 1,300 animals representing eight different lines. They have used single nucleotide polymorphisms (SNPs) markers based on candidate genes involved in synthesis and metabolism of the compounds androstenone and skatole.

Through a testing and selection process, significant progress is being made towards a genetic solution to boar taint. Work is continuing to characterize additional SNPs for boar taint and validate these markers in commercial swine populations.

The control of boar taint by marker assisted selection will eliminate the need for castration. The development of low boar taint lines of pigs will improve the profitability of pork production and address the animal welfare concerns about castration.