Preliminary Test of the Reduction Capacity for the Intestinal Adsorption of Skatole and Indole in Weaning Piglets by Pure and Coated Charcoal.

Abstract

Simple SummaryTo suppress or prevent boar taint, many strategies are available, e.g., surgical or immunocastration or different housing and feeding conditions. In Germany, male piglets may no longer be castrated without anesthesia until the 7th day of life for animal welfare reasons. The aim of this study was to reduce skatole and indole, two of the boar taint-causing substances, by the feeding of charcoal. A fat coating applied on charcoal could delay the unspecific adsorption of charcoal until entry to the large intestine where skatole and indole should be adsorbed since the fat coating is digested during its passage through the small intestine. In total, 18 piglets were divided into three feeding groups and were fed for 19 days with the control feed or with the control feed plus 2% charcoal or plus 4% charcoal coated with a fat layer. The skatole and indole concentrations were analyzed in chyme retrieved from the colon and caecum as these substances need to be adsorbed by charcoal in the intestine to prevent resorption into the bloodstream and accumulation in fat. The reduction in skatole and indole contents underlines charcoal’s adsorption capacity. The adsorption capacity was higher when the charcoal was coated. As charcoal reduced skatole and indole, feeding trials with adult boars are needed to observe the status of boar taint substances at the day of slaughter.To reduce the risk of boar taint, intact male piglets are immuno- or surgically castrated. One alternative is reducing skatole by adding skatole reducing or adsorbing substances to the boars’ diet. Charcoal with a high capacity for adsorbing skatole and indole in vitro (tested before, data not shown) was fed to the boars to test the hypothesis that a fat coating prevents the unspecific adsorption of charcoal before entry into the large intestine while increasing skatole adsorption. Twelve male and six female weaning piglets with initial body weights of 7.74 ± 0.75 kg were fed for 18 (or 19) days with either 2% pure (untreated) charcoal or 4% coated (50% charcoal + 50% fat-coating) charcoal or no charcoal. After euthanasia, skatole and indole were quantified in caecum and colon chyme. Skatole and indole contents in caecum chyme were significantly lower (p < 0.05) in the group fed with coated charcoal (33 ± 4.2, 7 ± 2.8 µg/gDM, respectively) than in the group fed with pure charcoal (51 ± 7.3, 14 ± 3.0 µg/gDM) or with no charcoal (73 ± 12.6, 15 ± 1.7 µg/gDM). Similar effects were obvious for colon chyme. The results indicate that a fat coating of charcoal might prevent unspecific adsorption in the small intestine and might consequently lead to a higher adsorption capacity for skatole and indole in the large intestine, as skatole and indole concentrations in the chyme of caecum and colon were approximately 50% lower in the piglets who received coated charcoal.