Developing novel probiotics and evaluating their mechanisms of interaction with host environment to enhance poultry performance
There are well documented problems associated with the contionous use of antibiotics in the poultry industry. Over the past few decades, probiotics have emerged as viable alternatives to antibiotics; however the mode of action of these probiotics is not clearly understood. The overall goal of this study was to evaluate the modes of action of probiotics and their interaction with host, the broiler chicken. Amplification of the hypervariable region of the 16s rRNA gene was used to distinguish gastrointestinal tract (GIT) microbes of chicken and Guinea fowl (GF). 16s DNA library was constructed and sequencing template prepared using IonOneTouch-2 system. Sequencing data were analyzed using Core QIIME pipeline with GreenGenes and Microseq ID databases for phylogenetic diversity. Gut microbial profiles of chicken and GF revealed taxonomic diversity consisting of almost 150 families and diverse probiotic bacteria suggesting that the constitution of probiotics should be species specific. Acid and bile tests revealed the optimum prevalence of S. coelicolor was at pH 4-6.5 and 0-3.5% of bile concentrations. L. reuteri and S. coelicolor were selected from established microbial profiles and encapsulated to supplement with dietary treatments to the birds. In an 8 week study, 240 day old chicks and 216 day old Guinea keets were randomly assigned to four dietary treatments. The selected L. reuteri and S. coelicolor were added to the feed by using wheat middlings as a carrier at concentration of 100ppm (100mg/kg). Three dietary treatments contained two probiotic bacteria in three different proportions as L. reuteri and S. coelicolor individually at 100ppm, and mixture of L. reuteri and S. coelicolor at 50ppm each and the fourth treatment which had no probiotic bacteria served as control diet. Chickens fed diets containing L. reuteri and S. coelicolor mixture showed improved body weight gain, feed consumption, and decreased feed conversion ratios. The GF fed L. reuteri showed improved body weight gain and feed consumption. The GF fed S. coelicolor showed lower feed conversion ratios when compare with other dietary treatments. Feeding these probiotics revealed 261 and 73 gene transcripts in the liver and intestine of broiler chickens, respectively, which were either up or down-regulated. Feeding probiotics was also associated with changes in about 90 metabolic pathways in the broiler chickens. This research therefore suggests that L.reuteri and S.coelicolor have the potential to constitute probiotics for both chickens and Guinea fowl combined or separately depending on choice of performance index.
"Developing novel probiotics and evaluating their mechanisms of interaction with host environment to enhance poultry performance"
ETD Collection for Tennessee State University.