Effects of synbiotic supplementation of high fibre diet on growth performance, intestinal microbial ecology, jejunal histomorphology and carcass characteristics of broiler chickens
This study determined effect of synbiotic supplementation on growth performance and carcass quality of broiler chickens fed high fibre diets and to evaluate the effects of synbiotic on intestinal microbial ecology and jejunal histomorphology of broiler chickens fed this diet with a view to establishing the beneficial effect of synbiotic supplementation in high fibre diet on broiler chickens. The experiment was carried out at the Poultry Unit of the Teaching and Research Farm of Obafemi Awolowo University, Ile-Ife, Osun State, Nigeria. A total of three hundred and twenty (320) three-week old Arbor acre chicks were used for the research consisting of eight treatments (T1- T8) replicated four times and ten birds per replicate. The experimental design was a 2x2x2 factorial arrangement, consisting of two agro-industrial by-products at two inclusion levels with and without synbiotic (containing mannan oligosaccharide and Saccharomyces cerevisae) supplementation. The synbiotic was supplemented at 1g/kg of feed at the expense of maize and birds on T1-T4 received wheat offal based diet at 20% (without synbiotic), 20% (with synbiotic), 40% (without synbiotic) and 40% (with synbiotic) respectively while while T5-T8 received palm kernel cake based diet at 20% (without synbiotic), 20% (with synbiotic), 40% (without synbiotic) and 40% (with synbiotic) respectively. At the end of the five-week study, three birds with weight representative of each treatment were selected and slaughtered for carcass characteristics and evaluation of jejunal histomorphology and microbial ecology in small intestine and caecum. Birds fed diets supplemented with synbiotic did not differ (P>0.05) in feed intake from the non-supplemented group and supplementation decreased (P<0.05) final body weight (FBW), daily weight gain (DWG) and increased feed conversion ratio. In terms of fibre sources, birds fed wheat offal based diets (WO) had higher (P<0.05) feed intake than those fed palm kernel cake (PKC) based diets but did not translate to significant change in body weight gain. Relative weights of breast, wings, thigh and drumstick were not affected (P>0.05) by synbiotic supplementation. Synbiotic supplementation had negative effect (P<0.05) on nutrient digestibility except crude ash. Birds fed WO had higher (P<0.05) dry matter digestibility compared to those fed PKC. Birds fed 20% fibre ingredient had higher (P<0.05) nutrient digestibility values than those fed at 40% inclusion level. Birds fed synbiotic supplemented diets had higher (P<0.05) colony count of enterobacteria in ceaca and E. coli in both ceaca and small intestine than the non-supplemented group. Birds fed WO had higher (P<0.05) enterobacteria, E. coli and Lactobacillus spp. counts in ceaca and small intestine compare to those fed PKC based diet. Birds fed diets without synbiotic had higher (P<0.05) villi height, crypt depth, and full mucosal in the jejunum than the birds fed diets supplemented with synbiotics. Birds fed WO had increase (P<0.05) in crypt depth and sub-mucosal than those fed PKC. Birds fed high levels of fibre diet had increased (P<0.05) villi height, crypt depth and villi:crypt ratio. The study concluded that synbiotic supplementation of high fibre diet had a negative effect on the overall performance of broiler chickens.