Studies from organic pig farms in Denmark show that levels of hormones associated with boar taint vary with liveweight, location and season of the year and, to a lesser extent, on the cleanliness of the animal and its housing.
Findings from two new Danish studies could help organic pig farmers reduce the incidence of boar taint, without resorting to surgical castration. Results were published recently in the scientific journal, Animal.
Researchers from Denmark’s Aarhus University and Newcastle University in the UK investigated factors that affect the occurrence of the hormones that cause boar taint, an unpleasant odor that can develop when cooking meat from sexually mature male pigs. Traditionally, male pigs have been castrated within a few days of birth to prevent the development of these hormones — androstenone and skatole — but in recent years, animal welfare concerns have prompted the development and adoption of alternative methods.
According to the researchers, organic rules prohibit the use of some of alternatives, so boar taint poses a particular challenge to organic pig producers. Gaining a better understanding of how and when boar-taint hormones develop in organically raised male pigs is therefore critical to identifying solutions for this sector.
The studies were conducted on five organic farms in Denmark. The first study examined levels of androstenone and skatole in the pigs relative to the season of the year and body weight. The average level of androstenone was higher than skatole, but both varied widely between and within the herds studied. Around the weight range that organic pigs are usually marketed, concentrations of both hormones were lower in the lighter animals, although neither was affected by the age of the pig.
Androstenone levels were higher in winter than in summer, but there was no seasonal effect on skatole concentration.
In a second study, the researchers evaluated the same pigs for fat concentrations of the two hormones and also conducted a human-nose sensory test. This time, they looked at the results in relation to the cleanliness of both the indoor and outdoor pens where the pigs were kept. The human-nose sensory test is a scientific method to measure odors in the same way that they would be perceived by a person.
Not surprisingly, the degree of pen soiling significantly affected pig soiling. Outdoor pen soiling was significantly linked to skatole concentration, although this was affected by both herd and season. By contrast, soiling of indoor pen areas did not affect skatole or androstenone levels. However, these were affected by the soiling of the pigs; the larger the area of the head and abdomen covered in manure, the higher the skatole concentration. Neither boar taint measure was affected by the thickness of the manure layer.
The researchers commented that while there was a wide variation in the different boar taint measures for both high and low scores of pen and pig soiling, the difference in skatole and androstenone concentrations between the high and low soiling categories was small. The human nose test did not reveal any effect from pig soiling.
“Decreasing live weight at slaughter could be an applicable management tool to reduce risk of boar taint and the level of tainted carcasses for a future production of entire male pigs within the organic pig production system,” concluded lead investigator Dr. Rikke Thomsen and her colleagues. “While increasing the hygiene management could be a strategy for reducing boar taint in production of organic entire male pigs, it should be emphasized that other factors would also need to be considered.”
To view the full abstracts, click on the links below: