Dietary preferences for feeds varying in threonine concentration by the piglet

Two choice feeding trials were carried out to investigate if weaned piglets prefer feeds varying in threonine (Thr) content. In exp 1, two control groups were fed either a 0.57% Thr (negative control) or a 0.67% Thr (positive control) feed. Two other groups had the choice from 2 feeds containing 0.57% or 0.62% Thr (Thr-choice 1) and 0.57% or 0.67% Thr (Thr-choice 2). In exp 2 the two control groups were fed either a 0.50% Thr (negative control) or a 0.62% Thr (positive control) feed and the Thr-choice groups had the choice from 2 feeds containing 0.50% or 0.56% (Thr-choice 1) and 0.50% or 0.62% Thr (Thr-choice 2), respectively. In exp 1, animals of the Thr-choice 1 showed a significant preference for the feed with the higher Thr content but in the Thr-choice 2, both feeds on offer were chosen at random. In exp 2 the preference for the higher Thr feeds in the Thr-choice groups 1 and 2 was on average 71% and 72%, respectively. In both experiments, the data of growth performance and plasma amino acid and urea pattern indicated a suboptimal Thr supply in the negative control and the Thr-choice 1 group. It is concluded that piglets are able to detect metabolic changes caused by a marginal Thr supply and that they change their feeding behaviour in order to overcome deficiency.