Veterinarni Medicina, 54, 2009 (2): 47–63 Original Paper 47 Te efect of kaolin feeding on efciency, health status and course of diarrhoeal infections caused by enterotoxigenic Escherichia coli strains in weaned piglets M. Trckova, H. Vondruskova, Z. Zraly, P. Alexa, J. Hamrik, V. Kummer, J. Maskova, V. Mrlik, K. Krizova, I. Slana, L. Leva, I. Pavlik Veterinary Research Institute, Brno, Czech Republic ABSTRACT: Te purpose of the present study was to assess the efect of kaolin feeding on health status, body weight gain (BWG), course of diarrhoeal infections caused by enterotoxigenic strains of Escherichia coli (ETEC) and the level of mycobacterial contamination in weaned piglets. Te testing was performed in two experiments involving 40 weaned piglets at the age of 28 days. In the infection-free experiment, piglets were fed a diet without (C0) or with 1% content of kaolin (K0) for 20 days. Subsequently, all of them were fed the same diet without kaolin supplementa- tion for 39 days. Identical diets were fed during the infection experiment, and moreover, both groups (CI and KI) were orally infected with ETEC (O141:F18ac, STa+) on Day 1 of experiment. Te short-term feeding of kaolin to weaned piglets had a signifcant positive efect on their BWG. During the period of feeding the kaolin-containing diets, BWG in C0 and K0 were 0.20 and 0.29 kg, respectively (P < 0.05), and in CI and KI 0.13 and 0.19 kg, respec- tively (P < 0.05). Tere was no evidence of side efects to their health, neither was there any change in biochemical and haematological profles. In the infection experiment, a protective efect of kaolin on the course of ETEC infec- tion was evident. Colonization and shedding of ETEC by piglets fed the kaolin diet were milder and had a shorter duration in comparison with control piglets. Te culture examination of pure kaolin and kaolin containing diets for mycobacteria were negative. Potentially pathogenic mycobacteria occurring in the environment were isolated from faeces and tissues of pigs. According to these results, supplementation of diets with 1% kaolin to prevent diarrhoea in piglets and to support their growth in the critical post-weaning period could be recommended. Keywords: kaolinite; aluminosilicate; clay; feed additives; enterosorbents; pig; growth; serum biochemistry; hae- matology; diarrhoea; Mycobacterium avium complex; feed safety Supported by the Ministry of Agriculture of the Czech Republic (Grants No. MZE 0002716202 and No. QH 71054). Infections which cause diarrhoea in weaned pig- lets are one of the most common causes of seri- ous economic loss in swine herds (Madej et al., 1999; Hedemann and Jensen, 2004; Melin et al., 2004). Among pathogens, Escherichia coli infec- tions caused by enterotoxinogenic strains of E. coli (ETEC) are found most frequently (Alexa et al., 1995, 2001; Bertschinger, 1999; Melin et al., 2004). Until recently antibiotic treatment and vaccination were primarily used to prevent enteric diseases in piglets. In 2002, the European Commission pro- posed new safety measures for the use of supple- ments in animal diets. An absolute ban on the use of antibiotic growth stimulators came into force in 2006 (Anonymous, 2002; Castro, 2005; Chen et al., 2005), mainly due to the potential occurrence of cross resistance to antimicrobial agents that are used in human medicine (Barton, 2000; Castro, 2005; Chen et al., 2005). Likewise, the requirements for health safety and safety of food of animal origin