Fibre degrading enzymes and Lactobacillus plantarum influence liquid feed characteristics and the solubility of fibre components and dry matter in vitro ☆ P. Christensen a , V. Glitsø b , D. Pettersson b, ⁎ , B. Wischmann a a Danish Technical University, Food Biotechnology and Engineering Group, Biocentrum, DK-2800 Lyngby, Denmark b Novozymes A/S, Department of Feed Applications, DK-2880 Bagsvaerd, Denmark Abstract The effect of fibre degrading enzymes in combination with Lactobacillus plantarum on feed viscosity and pH and on solubilisation of non-starch polysaccharides (NSP) was studied in vitro using diets composed of cereals and soybean meal. The diet was incubated over time up to 24 h as liquid feed or liquid feed added L. plantarum and in addition both feeds were treated without or with fibre degrading enzymes. Spontaneous fermentation developed in the liquid feed without L. plantarum and became noticeable after a period of 6 to 8 h, when pH began to drop. From 8 to 24 h there was a slow but steady reduction in pH down to a level of about pH 4.3. This development was irrespective of enzyme supplementation level. The L. plantarum treatment had already reached a pH of 4.2 after 8 h and a pH of 3.6 after 24 h. The viscosity was reduced with supplementation with a high enzyme dose (6000 FXU and 600 FBG per kg diet), compared to the control diet (without enzymes). Treatment with L. plantarum (1.8 × 1011 CFU/kg feed) increased the viscosity over time, even with enzyme supplementation, compared to the control treatment. Diets without and with enzyme supplementation and pre-treated as dry feed (control), liquid feed (incubated for 8 h) or liquid feed fermented with L. plantarum (incubated for 24 h), were subjected to an in vitro digestion procedure. Both pre-treatment as liquid feed and enzyme supplementation lead to a reduction in dry matter and in the insoluble NSP fraction during digestion in comparison with the control based on the original dry feed. It may be concluded that enzyme supplementation to liquid or fermented feed may cause a reduction in the insoluble dietary fibre content as well as a reduction in feed viscosity, while the pH is not influenced. © 2007 Elsevier B.V. All rights reserved. Keywords: Liquid feed; Fermented feed; Lactobacillus plantarum; Enzyme supplementation; In vitro 1. Introduction The use of inexpensive by-products, from e.g. the milling industry, is one of the major reasons for installing liquid feeding systems in order to reduce feeding costs. In addition, the improvement of pig health when using such feeding systems has been reported Livestock Science 109 (2007) 100 – 103 www.elsevier.com/locate/livsci ☆ This paper is part of the special issue entitled “Digestive Physiology in Pigs” guest edited by José Adalberto Fernández, Mette Skou Hedemann, Bent Borg Jensen, Henry Jørgensen, Knud Erik Bach Knudsen and Helle Nygaard Lærke. ⁎ Corresponding author. Tel.: +45 44421742; fax: +45 44428600. E-mail address: danp@novozymes.com (D. Pettersson). 1871-1413/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2007.01.097