The intestine plays an important role in the ingestion and absorption of nutrients, and provides a physiologic and immunologic barrier to a wide range of microorganisms and foreign substances (McGuckin et al., 2011; Pérez-Sánchez et al., 2013). In a previous study, Nya and Austin (2011) reported an increase in the activity of digestive enzymes (total proteases, pepsin and alkaline phosphatase) after the oral administration of LPS from E. coli (0.015%) for 14 days, although these results were not coupled with an increase in feed digestibility and growth performance. In the present study, although the incorporation of LPSp in rainbow trout feeds did not enhance digestive (pancreatic and intestinal) enzyme activities nor affected the size of intestinal folds, it had a direct on the number of intestinal goblet cells in fish fed 20 μgLPSpkgBW
−1
day
−1
. Similar results were observed in channel catfish fed diets containing yeast polysaccharides (Zhu et al., 2012). The increase in the number of goblet cells would benefit the host by