Studies on the influence of the probiotic enterococcus faecium NCIMB 10415 and the trace element zinc on performance and digestive physiological parameters in the small intestine of piglets

The first study of the PhD thesis concentrates on the probiotic strain Enterococcus faecium NCIMB 10415 (E. faecium) in suckling and weaned piglets. The strain was chosen since it is a frequently used feed additive for young piglets. It has been shown to decrease the occurrence of PWD and to affect immunological parameters after weaning (Scharek et al., 2005; Taras et al., 2006). Other potential beneficial effects of probiotics, amongst others, are the competitive exclusion of pathogens (Servin, 2004) or stimulation of other beneficial gut microbes in the small intestine, especially lactobacilli (de Lange et al., 2010; Vahjen et al., 2002). However, little is yet known about the influence of probiotic treatment on digestive physiological parameters such as expression and activities of digestive enzymes. Recent studies in simplified models such as gnotobiotic or mono-associated piglets indicate that specific microorganisms might influence these parameters in different ways (Kozakova et al., 2006; Willing and Van Kessel, 2009). Another frequently used strategy and the main focus of the second part of the PhD thesis is the use of zinc oxide at high dietary levels to enhance growth performance and reduce the incidence of PWD syndrome in weanling piglets (Pettigrew, 2006). Although many studies have been conducted, the mechanisms have not yet been fully elucidated. Since zinc is an important co-factor for enzymes within the digestive process and due to its ubiquitous role in structural and regulatory processes in the organism, it can be hypothesized that zinc in very high dosages will affect manifold mechanisms including the expression and activity of digestive enzymes. Therefore, the aim of the current thesis is to evaluate these two feed additives in three animal feeding trials including performance, health parameters, nutrient digestibility, and possible effects on physiological processes like gene expression and digestive enzyme activities in young piglets around the critical time of weaning.