Immunological castration has the potential to improve the sustainability of European swine production, with proven benefits in terms of pork quality, economic performance, animal welfare and environmental impact. This alternative is not yet widely used in Europe, where physical castration is still common practice in most countries. But with a clearer framework for measuring the sustainability of this technique, scientists believe that immunological castration could gain greater market acceptance.

In a report in Sustainability,¹ a team of scientists in Europe said that male piglets in Europe have been physically castrated for centuries to avoid some of the negatives of rearing boars. Barrows (castrated male pigs) have a lower risk of boar taint, an unpleasant odor that can occur when cooking meat from sexually mature male pigs. Reduced aggression in barrows is also linked to better welfare and carcass quality, they noted.

However, they added, physical castration has come under criticism in recent years in Europe “because it is painful and hurts the animals’ integrity.” Meanwhile, there is growing recognition of the economic and environmental benefits of keeping boars intact, such as more efficient feed conversion, reduced nitrogen excretion and a higher protein accretion compared to barrows and gilts.

Despite an agreement among many European swine industry stakeholders to ban surgical castration by 2018, most male piglets in Europe are still castrated without pain relief or anesthesia, the report noted. But according to the researchers, a technique known as immunological castration (also known as immunocastration) could provide a sustainable alternative by helping European producers harness the economic and environmental benefits of boar production while mitigating risks to welfare and product quality.

Immunological castration

Immunological castration involves vaccinating male pigs against gonadotropin-releasing hormone, thereby delaying the onset of puberty. As a result, the technique has been shown to reduce the accumulation of androstenone and skatole, the naturally occurring compounds that are responsible for boar taint.

The vaccine, marketed in Europe as Improvac^®, is given in two doses: The first dose, which is recommended around 12 weeks of age, serves to prime the immune system. But the puberty-delaying effects of the vaccine don’t kick in until after the second dose, which is given about 4 to 6 weeks before slaughter.

This means that vaccinated pigs spend most of the fattening period growing like boars, which gain more weight, convert feed more efficiently and produce less manure compared to barrows and gilts.

Following the second dose, vaccinated pigs switch from boar to barrow-like status, and growth efficiency drops. But on the plus side, boar-taint risk is limited, aggressive behavior is reduced, and the pigs deposit fat in a way that is more consistent with barrows and generally considered more palatable to consumers.

Filling knowledge gaps

Immunological castration therefore provides a higher-welfare alternative to physical castration that allows producers to strike a balance between the naturally superior growth efficiency of boars and the behavioral and meat-quality benefits of barrows. However, despite being approved in Europe since 2009 and widely used in markets such as Canada, Brazil, Australia and several others, the researchers noted that the technique is still not widely used in Europe.

“Little practical experience of stakeholders and no targeted communication about the consequences of [immunological castration] of European pig genotypes for management, feed requirements and product quality exist in the market,” the researchers wrote, adding that these knowledge gaps may explain why a method that might have economic, ecological and societal advantages is still not widely embraced.

To address the knowledge gaps, the researchers conducted a comprehensive review of scientific literature to demonstrate the benefits and trade-offs of the vaccine according to the three pillars of sustainability: society (including animal health, welfare and product quality), economy (including production performance and carcass quality) and the environment (including feed conversion and natural resource use).

They also looked at how interactions between various factors of sustainability can lead to synergic and conflicting relationships both within and among the pillars (Figure 1).²

For example, they wrote, “In immunocastrates, performance results are better than in barrows but worse than in boars. The environmental impact of pork production with immunocastrates is lower than with barrows but higher than with boars.”

Compared to boars, the level of aggression is considerably lower in vaccinated pigs, they added. Meanwhile, societal concerns are mainly related to food safety and are not supported by any scientific evidence.

Finding the right balance

Since vaccinated pigs perform like barrows following the second vaccination, the researchers suggested that the timing of the second dose may allow producers to tailor product quality to the demands of different pork markets. Ultimately, they said, the decision has to be balanced between the conflicting aims of desirable, boar-like growth efficiency and lean meat content, on the one hand, with the superiority of barrows in terms of behavior and meat quality on the other.

“High product quality with low boar-taint levels and higher levels of intramuscular fat work well with production systems which optimize welfare aspects through an early second vaccination. These advantages have to be balanced against the higher anabolic potential of boars which can create economic and environmental benefits,” they wrote.

“The later the second vaccination is applied, the better its effects for the environment and for farm profitability.

“Within the value chain, targeted communication about the impact of the timing of the second vaccination is essential in order to make use of this opportunity to produce meat quality tailored to various market segments with different impacts on sustainability.”

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