The effects of dietary fructo-oligosaccharide addition on boar taint compounds and performance in heavy slaughter weight boars and gilts

• We determined the effects of dietary short chain fructo-oligosaccharide in heavy pigs.
• We examined effects on performance plus skatole levels in digesta, faeces and backfat.
• A 2 g/kg dietary inclusion of scFOS had no effect on performance.
• scFOS had no consistent significant effect on colonic/faecal skatole or indole levels.
• scFOS reduced skatole concentration in carcass fat reducing risk of carcass taint.

Increasing slaughter weight in finishing pigs may increase the risk of carcass taint from compounds such as skatole. An experiment was carried out to determine the effects of dietary inclusion of short chain fructo-oligosaccharide (scFOS), on performance, the levels of skatole in digesta, faeces and backfat in heavy slaughter weight boars and gilts. Pigs (n = 112), with an initial bodyweight of 57 ± 1.15 kg. (mean ± SD), were allocated in a randomised complete block arrangement in four replicates over two time blocks. Pigs were allocated to one of two dietary treatments, Negative Control (NC) and Negative Control plus 2 g/kg scFOS and separated by gender, boar and gilt to create a 2 × 2 factorial design. Pigs were housed in single sex pens of 6–8 pigs in controlled-environment, partially-slatted pens. The Basal NC diet was a commercial pelleted finisher diet (170.8 g/kg CP, 13.37 MJ/kg DE, 10.3 g/kg Lysine) fed ad-libitum. The scFOS preparation contained kestose, nystose and fructosyl nystose.Pen feed intake was calculated weekly with pigs being weighed and backfat measurements taken every two-weeks to calculate daily live weight gain with back fat at the P2 position measured ultrasonically. Faecal samples were taken at each weighing, and colon content and backfat samples were taken at slaughter. Data were evaluated using analysis of variance. Boars were more efficient than gilts at this heavier weight range, but back fat thickness showed no difference between genders. Faecal indole concentration increased with age, but faecal skatole did not reflect this increase. A 2 g/kg dietary inclusion of scFOS had no effect on performance and no consistent significant effect on skatole or indole concentrations in faeces or in the colon digesta at slaughter. However, scFOS did reduce (P < 0.009) the carcass fat concentration of skatole thus reducing risk of carcass taint. This effect was more pronounced in the boars due to their higher fat skatole concentration. These results suggest a 2 g/kg dietary inclusion of scFOS in finisher diets would be beneficial in reducing carcass taint but not in the reduction of malodorous faecal compounds.