Dietary self-selection for organic acids by the piglet

Two feeding trials using 48 weaned crossbred piglets each were carried out to determine the effect of acidifying diets with potassium diformate (K-diformate), formic or sorbic acid on dietary preferences in piglets. In Exp. 1 two reference groups were fed either an unacidified diet or a diet containing 2.4% of K-diformate with no choice for selection. Furthermore, piglets in choice group 1 and 2 had the choice between an unacidified diet and a diet supplemented with 1.2 and 2.4% K-diformate, respectively. In Exp. 2, animals of three reference groups received exclusively an unacidified diet or diets supplemented with 1.2% formic acid or 1.2% sorbic acid, respectively. The animals of the choice groups had the choice between an unacidified diet and diets with 1.2% formic acid or 1.2% sorbic acid, respectively. In Exp. 1 average daily feed intake, daily gain and feed conversion ratio were 751 g, 458 g and 1.64 kg/kg, respectively, with no significant differences between treatments. In both choice feeding groups animals chose the diets on offer at random (each around 50%). In Exp. 2 growth and feed intake were not affected by the treatment, but feed conversion ratio was enhanced due to the 1.2% formic acid supplementation. Animals of both organic acid choice groups showed a significant preference for the unacidified diets in each experimental week. The formic acid and sorbic acid diets represented on average only 13.5% and 23.5% of the total feed intake. The present results demonstrate that the inclusion of 1.2% sorbic or formic acid or 2.4% of K-diformate in piglet diets has no negative impact on feed intake, but in a situation of choice feeding, piglets will refuse diets acidified with 1.2% formic or sorbic acid, presumably because of negative taste cues. Acidifying the diets with varying amounts of a K-diformate had no effect on dietary preferences of piglets.