Altogether, the EF treatment did not markedly affect performance of the piglets except for a lower FCR in the EF group. A positive effect on FCR might be of economic value for swine industry in order to reduce production costs. However, the number of animals used in the current study was relatively low and field trials should help to determine whether the use of EF for piglets would have an economic impact. The incidence of softer feces was generally very low making it difficult to draw conclusions about possible diarrhoea-preventing effects of EF application. In a previous study, Zeyner and Boldt (2006) showed that EF led to a higher daily body weight gain and a reduction of diarrhoea occurrence in the piglets on farm-level when the incidence of diarrhoea was generally high (40% of all piglets in control group). Another study reported a reduction of diarrhoea when EF was fed to sows and their piglets (Taras et al., 2006). Thus, the fact that fecal scores were unaffected in the current study could be attributed to the good sanitary conditions. It has previously been shown that feed additives can differentially modify the intestinal environment when used under experimental or farm conditions with different hygienic standards (Janczyk et al., 2010), where the application of feed additives had more influence under farm conditions with a lower hygienic standard. Thus, the influence of EF on intestinal health should be studied in well-defined challenge models such as Salmonella enterica ser. Typhimurium (Szabo et al., 2009; Mafamane et al., 2011) to determine whether EF can promote ‘intestinal health’ in piglets. The low incidence of diarrhoea in the current study and the unimpaired health condition of the animals was also reflected by the digestibility of proximate nutrients. Neither ileal nor total tract digestibility of proximate nutrients was affected by supplementation of EF. This is in agreement with a previous report by Böhmer et al. (2005), showing that EF treatment had no significant effect in growing pigs. They showed that the EF treatment alone had no significant effect on ileal and fecal digestibility of nutrients, with exception of total tract crude fibre digestibility which tended to be lower with EF treatment.