Alternative anticoccidial treatment of broiler chickens

Abstract

This thesis describes the effects of mannanoligosaccharides (MOS) and electromagnetic fields (EMF) in broiler chickens infected with Eimeria parasites. The question addressed was whether ingestion of MOS or exposure to EMF would counteract the coccidiosis-induced depression of growth performance and would reduce oocyst shedding and the severity of intestinal lesions. In other words, the question addressed was whether MOS or EMF could serve as an alternative to the anticoccidial drugs currently used. A literature review provides insight in the life cycle of coccidia and its relation with necrotic enteritis, the gut immune system, and its response during occidiosis. The review also highlights the methods used in the control of coccidiosis, drug resistance, and alternatives to coccidial drugs (Chapter 1). In two different experiments, the effect of MOS was studied in broiler chickens infected with either a single dose of E. tenella (Chapter 2) or a mixture of Eimeria containing low doses of sporulated oocysts of E. acervulina, E. maxima, and E. tenella (Chapter 3). Possible effects of a weak electromagnetic field (EMF) on body weight, feed conversion ratio, feed intake, oocyst counts and severity of coccidial lesions where tested in broiler chickens infected with a mixture of Eimeria containing sporulated oocysts of Eimeria acervulina, Eimeria maxima, and Eimeria tenella. The infection was being imposed by either crop gavage (Chapter 4) or by contaminated litter (Chapter 5). In Chapter 6 different methods of infection and their characteristics are described with emphasis on a nature-like-infection under controlled conditions. In the General Discussion section, an attempt is made to value MOS and EMF as alternative anticoccidial treatments of broiler chickens.