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Summary For the last several decades, antimicrobial compounds have been used to promote piglet growth at weaning through the prevention of subclinical and clinical disease. There are, however, increasing concerns in relation to the development of antibiotic‐resistant bacterial strains and the potential of these and associated resistance genes to impact on human health. As a consequence, European Union (EU) banned the use of antibiotics as growth promoters in swine and livestock production on 1 January 2006. Furthermore, minerals such as zinc (Zn) and copper (Cu) are not feasible alternatives/replacements to antibiotics because their excretion is a possible threat to the environment. Consequently, there is a need to develop feeding programs to serve as a means for controlling problems associated with the weaning transition without using antimicrobial compounds. This review, therefore, is focused on some of nutritional strategies that are known to improve structure and function of gastrointestinal tract and (or) promote post‐weaning growth with special emphasis on probiotics, prebiotics, organic acids, trace minerals and dietary protein source and level.

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Phenotypic and genetic traits of porcine intestinal spirochete strain P43/6/78' (= ATCC 51139T) (T = type strain), which is pathogenic and weakly beta-hemolytic, were determined in order to confirm the taxonomic position of this organism and its relationships to previously described species of intestinal spirochetes. In BHIS broth, P43/6/7ST cells had a doubling time of 1 to 2 h and grew to a maximum cell density of 2 X 10' cells per ml at 37 to 42°C. They hydrolyzed hippurate, utilized D-glucose, D-fructose, sucrose, D-trehalose, u-galactose, D-mannose, maltose, N-acetyl-D-glucosamine, D-glucosamine, pyruvate, L-fucose, D-cellobiose, and D-ribose as growth substrates, and produced acetate, butyrate, ethanol, H,, and CO, as metabolic products. They consumed substrate amounts of oxygen and had a G+C content (24.6 mol%) similar to that of Serpulina hyodysenteriue B7ST (25.9 mol%). Phenotypic traits that could be used to distinguish strain P43/6/78' from S. hyodysenteriue and Serpulina innocens included its ultrastructural appearance (each strain P43/6/78' cell had 8 or 10 periplasmic flagella, with 4 or 5 flagella inserted at each end, and the cells were thinner and shorter and had more pointed ends than S. hyodysenteriae and S. innocens cells), its faster growth rate in liquid media, its hydrolysis of hippurate, its lack of P-glucosidase activity, and its metabolism of D-ribose. DNA-DNA relative reassociation experiments in which the Sl nuclease method was used revealed that P43/6/7ST was related to, but was genetically distinct from, both S. hyodysenteriae B78' (level of sequence homology, 25 to 32%) and S. innocens B256T (level of sequence homology, 24 to 25%). These and previous results indicate that intestinal spirochete strain P43/6/7ST represents a distinct Serpulina species. Therefore, we propose that strain P43/6/78 should be designated as the type strain of a new species, Serpulina pilosicoli.Porcine intestinal spirochetosis or spirochetal diarrhea is a disease of swine that are between 4 and 20 weeks old but typically occurs within 7 to 14 days after weaning (7, 39). The clinical signs of this disease include mucus-containing, usually nonbloody diarrhea; poor feed conversion; and depressed growth rates (1, 7, 31,40). The characteristic histological feature that distinguishes porcine intestinal spirochetosis is a dense mat or false brush border of spirochete cells which are closely packed parallel to one another and are attached by one end to the colonic epithelium (4, 7, 14,40). Such cells are not typical of infections caused by Serpulina hyodysenteriae (the agent of swine dysentery), but have been found in humans colonized by intestinal spirochetes, where their clinical significance is unclear (8, 22).The etiologic agent of porcine intestinal spirochetosis was first described in 1980 by Taylor et al. (40). These investigators successfully isolated an intestinal spirochete, designated strain P43/6/78T (T = type strain), and reproduced clinical signs and lesions typical of the disease in pigs that were o...