The main reason for the castration of male pigs is boar taint.

Boar taint is caused by two naturally occurring compounds known as androstenone and skatole, the odour of which is said to be comparable to sweat, urine and faeces. The two compounds can accumulate in the meat of boars (male pigs) whose testicles have not been removed or castrated. Only if available in high quantities, the compounds can be detected by people through taste and smell when they cook or heat the pork meat or meat products.

Interestingly, a study done in the EU to identify the proportion of consumers who were turned off by the smell or taste of boar-taint found that 30% if people can’t smell it, and that 20% actually like the smell. While there is a claim that as many as 20% of boars have boar taint, research has suggested that the figure is closer to 3 or 4%.

To avoid the problem of boar taint, it is the current practice to surgically castrate male pigs in the first weeks of life. Pig farmers usually do this themselves and are allowed, by law, to castrate male pigs up to a certain age. Anaesthesia is generally not used.

In addition to improving carcass quality by castrating male pigs, the other reasons offered for the procedure include:

• the reduction of aggression amongst males and the injuries associated with such aggression, and
• the prevention of  indiscriminate breeding and undesired pregnancies.

Although it has been proven that castrated males show less agression than intact males, the welfare issues of the procedure outweigh this benefit, especially if management practices are able to solve the agression issue.

In addition, intact animals are generally more efficient in the conversion of feed into lean meat. In addition to decreasing production costs, better feed efficiency also leads to a reduction in the output of various biological pollutants, particularly nitrogen.