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Williams, Jeanne
(2007).
DOI: https://doi.org/10.21954/ou.ro.0000ea1d
Abstract
The ban of antimicrobial growth promoters in pig production has resulted in an increased interest in investigating the effects of different alternatives, which can reduce the problems post weaning and improve the performance in piglets. Initially two botanical extracts with different properties were investigated: hops, which have antibacterial properties and silymarin, which is used for liver disorders.
The first experiment showed that hops and silymarin had beneficial effects on FCR in piglets (P = 0.014) by 9.6% and 15.8%, respectively. Furthermore, hops significantly improved some of the measured liver enzymes, so it was decided to focus on hops only.
Two further experiments were carried out examining the effects of different concentrations of hops and isolated hop compounds (iso-α acids and ß-acids), and the combination with organic acids in weaner pigs. A higher inclusion level of hops was associated with a better FCR, and the isolated hop compounds also resulted in an improved FCR (P = 0.027) by 9.2%. The addition of an organic acid mixture did not affect the performance.
An in vitro experiment confirmed that hops and isolated hop compounds had antibacterial properties. To try and elucidate the mechanism by which the hops and the isolated hop compounds improved the FCR, the effects on the gut flora were studied in the piglets. Both the hops and the iso-α acids and ß-acids reduced the level of lactic acid bacteria and the level of Bacteriodes in one of the two experiments, but no effects were seen on the other bacteria. This lead to investigate the effects of hops/isolated hop compounds on the level of volatile fatty acids, digestibility and level of digestive enzymes and level of liver enzymes. However, none of these parameters gave conclusive results about the mode of action of hops/isolated hop compounds in the piglet.
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