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Type: Thesis
Title: Role of sweet potato fibre on energy utilisation, gut morphology, and gut microbiota in broilers
Author: Pandi, Janet Caritas Doru
Issue Date: 2017
School/Discipline: School of Animal and Veterinary Sciences
Abstract: Despite considerable research on the feeding value of sweet potato there is a dearth of information on how dietary fibre, in particular total non-starch polysaccharide (NSP) content of sweet potato roots can influence gut health of broiler chickens. It is well established that diet composition and ingredients affect the health of birds by influencing the internal gut environment and microbial status of the gastrointestinal tract of poultry. In developing countries such as Papua New Guinea (PNG), manufactured feed is expensive due to importation of most feed ingredients. Interventions into different practical diets for monogastric livestock using local ingredients for small holder producers are necessary for sustainable and efficient production under local environmental and management conditions. The impact of several selected local PNG sweet potato varieties with different total NSP contents was studied. Diets based on these varieties were fed to broiler chickens to investigate the effects of the total NSP contents on the apparent metabolisable energy (AME) of diets and growth performance, gut morphology, and detectable levels of Campylobacter, Salmonella and Clostridium perfringens in the ceca of these birds. Inclusion of an enzyme product in these diets was also assessed. It was found that sweet potatoes from PNG have an average total NSP content of 172 g/kg DM, and generally have higher fractions of insoluble compared to soluble NSPs. AME and digestibility of diets were influenced by the total NSP content. The variety with a low total NSP content had a lower AME value which was improved with enzyme inclusion. Varieties with high total NSP contents had AME values within the required levels for finishing broilers and inclusion of enzymes did not improve or elucidate any effects. Feed intakes were low in broilers fed with sweet potato and this translated into low end weights, weight gains, and poor feed conversion ratios (FCR), despite being high in energy and highly digestible. FCRs did improve with continuous feeding. Digestive capacity of broilers in terms of gut morphology was not influenced despite varying NSP contents. Total NSP contents did however, influence the load of enteric pathogens. Varieties with high total NSP contents had high levels of Campylobacter which were reduced with enzyme inclusion and marginally reduced with continuous feeding of sweet potato but this needs to be further investigated to validate this finding. Levels of C. perfringens were high in the variety with a low total NSP content but these levels were comparable to the sorghum diet and may not pose a risk of necrotic enteritis in broilers. Levels of Salmonella were low in diets with and without sweet potato. Strategies to reduce campylobacteriosis and salmonellosis in poultry famers and their families as well as product contamination associated with these zoonotic pathogens must be taken into consideration when developing food safety regulations and policies in PNG as broilers raised under these smallholder enterprises supply the informal live broiler chicken industry in PNG. There is currently a lack of surveillance data on the levels of these pathogens under village or smallholder poultry production systems, and information generated here could be used as baseline information for future research in terms of production parameters and managing bird health via nutritional feeding strategies.
Advisor: Chousalkar, Kapil
Dissertation Note: Thesis (Ph.D.) -- University of Adelaide, School of Animal and Veterinary Sciences, 2017
Keywords: Sweet potato
non-starch polysaccharides
broiler chickens
gut microbiota
Salmonella spp.
Clostridium perfringens
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