Abstract

Boar taint has been mainly associated with the presence of androstenone and skatole in adipose tissue of entire male pigs. This work was focused on the effects of breed, age, hormonal status, and diet composition on boar taint level. The results showed that skatole levels in entire male pigs varied considerably with age, and the degree as well as the pattern of this variation differs between different breeds. The initial increase in skatole levels might occur at a relatively young age of 8-10 weeks. Later, the levels of skatole decreased and remained low until puberty. As puberty development progressed, skatole levels increased again reaching very high levels in some individuals. The increase in skatole levels followed the increase in levels of testicular steroids. These findings indicate that there is a relationship between the process of sexual development and high skatole levels, and that the increase in the levels of testicular steroids at puberty may affect skatole levels. The decreased activities of the main enzymes controlling skatole metabolism in the liver also contributed to increased skatole levels during this period. No direct relationship between skatole and thyroid hormones and IGF-1 was found. The dietary supplement of raw potato starch or lower weight at slaughter reduced skatole levels in entire male pigs, but did not affect androstenone levels or the activities of cytochrome P4502E1 and cytochrome P4502A6. Raising entire male pigs in mixed pens resulted in increased skatole levels in plasma in pigs of 115 kg live weight fed raw potato starch. Androstenone levels were higher in pigs at 90 kg live weight raised in mixed pens, but not in heavier pigs. A new method to determine free oestrone in porcine adipose tissue was developed and applied to investigate the relationship between boar taint compounds and hormonal status in entire male pigs. Both skatole and androstenone were positively correlated to free oestrone levels. Overall, the results suggest that puberty is a main factor controlling androstenone levels. Skatole levels are regulated by a number of factors, including breed, age, hormonal status and diet.