Abstract:
The poultry industry is considered one of the most active and continuously growing agri-sectors in the world to fill the gap between demand and requirements of high-quality protein for human consumption. Despite the efforts made by the sector, the industry is facing continuous and substantial challenges concerning the cost of feed ingredients and diseases. To overcome these challenges, poultry farmers administer antibiotics to chickens for treatment of diseases and growth promotion. Today the general use of antibiotics in animal feed as growth promoters have been banned in many countries due to the concerns associated with potential risks of emerging antibiotic resistance pathogens. To overcome these challenges, the development, promotion, and application of safe, green, and efficient feed additives have become mandatory and trendy requirements for the industry. This study aimed to assess chicken production, isolate potential probiotic bacteria from the gastrointestinal tract of free-range locally selected Ethiopian chickens of different agro-ecological zones and to evaluate the probiotic potential of the isolates using in vitro and in vivo animal trials. The assessment study was carried out in the North Shewa Administrative Zones of the Amhara regional state, Ethiopia. Formal surveys were conducted based on individual interviews using semi-structured questionnaires, visual observations, and focus group discussions to describe the knowledge, attitude, and practice of poultry farmers towards antibiotic use. Potential probiotic bacteria candidates were isolated from 12 well-adopted free-range healthy young chicken’s gastrointestinal tract (GIT). Twelve bacterial isolates were selected based on their ability of tolerance to low pH and bile salt. The isolates were purified and characterized based on their morphological, biochemical, and molecular profiles. Low pH and bile salt tolerance, microbial antagonistic activity, antibiotic activity, hemolysis activity, adhesion to the tissue of chicken intestine, and carbohydrate fermentation tests were conducted to identify potential probiotic candidates. The in vivo study evaluated the performance of the two probiotic bacteria supplementations on the growth, and carcass quality of experimental Sasso chickens using a completely randomized design consisting of 4 treatment groups. The in vivo trial experiment were conducted with four groups consisted: T1, fed with basal diet only without added probiotics (control group); T2, given Lactiplantibacillus plantarum (L. plantarum) GCH212; T3, given Bacillus subtilis (B. subtilis) GCM412 and T4, given a probiotic cocktail consisting of both L. plantarum GCH212 and B. subtilis GCM412 cell suspension (1.2 x 109 - 1.5x109cfu/ml). The growth performances of chickens were measured by
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calculating FI (feed intake), BWG (body weight gain), and FCR (food conversion ratio) over the rearing period of 91 days. The carcass quality of meat portions and the relative weight of internal organs of chickens were evaluated. Statistical analyses of data were performed using SPSS version 20 software and significant differences among treatment groups were
