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Proceeding Book2022

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Abstract

The main scope of this symposium is to invite the experts to discuss the projects and applications on sustainable development in agriculture and environment. The main topic areas include interaction between agriculture and environment, social and economic aspects of environment, biology and agriculture, sustainable development, tropical agriculture, biodiversity, biotechnology, horticulture, plants, animal production, climate change, water management, soil conservation, integrated agriculture management, hydraulic structure, food security, and other related agriculture and environment issue.
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The perturbation of gut health is a common yet unresolved problem in broiler chicken production. Antibiotics used as growth promoters have remarkably improved the broiler production industry with high feed conversion efficiency and reduced intestinal problems. However, the misuse of antibiotics has also led to the increase in the development of antibiotic resistance and antibiotic residues in the meat. Many countries have enacted laws prohibiting the use of antibiotics in livestock production because of the increasing concerns from the consumers and the public. Consequently, one of the most significant discussions in the poultry industry is currently antibiotic-free livestock production. However, the biggest challenge in animal husbandry globally is the complete removal of antibiotics. The necessity to venture into antibiotic-free production has led researchers to look for alternatives to antibiotics in broiler chicken production. Many strategies can be used to replace the use of antibiotics in broiler farming. In recent years, many studies have been conducted to identify functional feed additives with similar beneficial effects as antibiotic growth promoters. Attention has been focused on prebiotics, probiotics, organic acids, emulsifiers, enzymes, essential oils, tributyrin, and medium-chain fatty acids. In this review, we focused on recent discoveries on gut health maintenance through the use of these functional feed additives as alternatives to antibiotics in the past 10 years to provide novel insights into the design of antibiotic-free feeds.
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Several natural products (NPs) have displayed varying in vitro activities against methicillin-resistant Staphylococcus aureus (MRSA). However, few of these compounds have not been developed into potential antimicrobial drug candidates. This may be due to the high cost and tedious and time-consuming process of conducting the necessary preclinical tests on these compounds. In this study, cheminformatic profiling was performed on 111 anti-MRSA NPs (AMNPs), using a few orally administered conventional drugs for MRSA (CDs) as reference, to identify compounds with prospects to become drug candidates. This was followed by prioritizing these hits and identifying the liabilities among the AMNPs for possible optimization. Cheminformatic profiling revealed that most of the AMNPs were within the required drug-like region of the investigated properties. For example, more than 76% of the AMNPs showed compliance with the Lipinski, Veber, and Egan predictive rules for oral absorption and permeability. About 34% of the AMNPs showed the prospect to penetrate the blood–brain barrier (BBB), an advantage over the CDs, which are generally non-permeant of BBB. The analysis of toxicity revealed that 59% of the AMNPs might have negligible or no toxicity risks. Structure–activity relationship (SAR) analysis revealed chemical groups that may be determinants of the reported bioactivity of the compounds. A hit prioritization strategy using a novel “desirability scoring function” was able to identify AMNPs with the desired drug-likeness. Hit optimization strategies implemented on AMNPs with poor desirability scores led to the design of two compounds with improved desirability scores.
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• This review describes different classes of antimicrobial peptides (AMP) found in the gastrointestinal (GI) tract of avian species, and their antimicrobial and immunomodulatory activities. The potential benefits of synthetic AMP in poultry production are examined, in the context of the use of AMP as alternatives to antimicrobial growth promoters (AGP). • Since the mid-1950s, antibiotic growth promoters (AGP) have been used in feed at low prophylactic doses to modulate the homeostasis of intestinal microbiota, decreasing the risk of intestinal dysbacteriosis and the growth of pathogens within the avian gut. Over the last three decades, AGP have faced major regulatory restrictions due to concerns of generating antimicrobial resistance (AMR). It is now well-documented that the rate of infectious disease outbreaks is higher in flocks which are not fed prophylactic antibiotics, resulting in a compensatory increase in antimicrobial use for therapeutic purposes. • Endogenous natural AMP production is associated with the presence of microbiota and their interaction with the intestinal epithelial and lamina propria lymphoid cells. Their antimicrobial activity shapes the beneficial microbiota population and control intestinal pathogens such Clostridium and Salmonella spp., and stimulates the development and maturation of the local immune system. • Similar to AGP, AMP can establish a well-balanced gut beneficial microbiota for adequate immune-competence, animal health and high growth performance parameters such as feed intake, daily weight, feed conversion and accumulated mortality. • Antimicrobial proteins and peptides constitute an essential part of the innate immune system of all organisms and protect the host from invading pathogenic bacteria, viruses, fungi, and parasites by interacting with the negatively charged pathogen membranes.
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The objective of this study was to investigate the impacts of Bacillus subtilis (BS), ATCC 6051a strain, as a probiotic bacterium in broiler diets based of 2 protein sources (soybean meal [SBM] and cowpea seeds [CWP]), on growth performance (GP), carcass traits, bone mineralization, and microflora population (0 to 42 d age). The SBM and CWP starter, grower, and finisher diets were tested in the presence or absence of BS (5.0 × 10¹¹ CFU spores g⁻¹ feed) in a 2 × 2 factorial arrangement of treatments in a completely randomized design. Broilers were randomly assigned to 4 dietary treatments with 6 replicate pens per treatment (20 chicks per pen). The results showed that broilers fed CWP had comparable GP (body weight gain, feed intake, and feed conversion ratio) to the birds fed the SBM diet. Carcass, breast and legs' yield, organ size (i.e., gizzard, liver, pancreas, small intestine, cecum), and bone development were not affected by the protein source. The addition of BS in both types of diet improved BWG (P < 0.001) and feed efficiency, especially in the grower and finisher period (P = 0.047; P = 0.043, respectively). In addition, BS significantly decreased abdominal fat (P = 0.026) and cecum weight (P = 0.034) and increased tibia bone P concentration (P = 0.015). Furthermore, BS decrease cecal pH (P = 0.010) and reduced Escherichia coli and Staphylococcus spp. from cecum and excreta broilers (P < 0.001; P < 0.0001, respectively). It is concluded that the BS significantly improved the GP of broilers and can beneficially affect the gut and excreta bacterial community in both SBM and CWP diets.
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Over the years the growth and health of food-producing animals have been enhanced by the use of antibiotics. These have helped reduce on-farm mortalities, lower incidences of diseases and more importantly improve productivity. Generally, the utilization of antibiotics in feed has been reevaluated since bacterial pathogens have established and shared a variety of antibiotic resistance mechanisms that can easily be spread within microbial communities. Multiple countries have introduced bans or severe restrictions on the non-therapeutic use of antibiotics. This has therefore warranted the urgent need for alternatives. Africa is facing its own challenges as it has been reported to be one of the continents with the highest number of foodborne diseases with approximately 91 million related diseases and 137,000 death per annum. Stakeholder and policy direction has been put in place to curb this escalation; however, the problem persists. The use of alternatives has been recommended and some successfully used in other countries as well as Africa, including pro-and prebiotics and phytochemicals. This then leads to the core aim of this review which is to (1) determine the extent to which antimicrobial-resistant pathogens have affected Africa, (2) assess the current measures put in place by Africa to reduces antimicrobial resistance and finally (3) explore the alternative use of antibiotics in poultry production. Improved sanitary conditions and farm biosecurity are important alternatives that could be adopted by farmers instead of depending on antibiotic drugs for disease control and prevention.
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The combination of lincomycin and colistin is widely used in poultry either for the prevention and treatment of bacterial infection or as additive. However, the presence of antimicrobial residues in food of animal origin is considered as threat to human health. Therefore, this study determined the withdrawal time (WT) by analyzing the residual concentration in tissues to overcome this problem. A combination product of lincomycin and colistin was administered to chickens. Antibiotic residues in edible tissues at different time-intervals were quantified using ELISA and chromatographic methods, and WT was determined. Antibiotics residues were high in the liver and kidney but were lower than the MRL on day 1 and rapidly decreased from day 3. The WT in the kidney was calculated as 2.95 days and is rounded off to 3 days. This study suggested the withdrawal time of 3 days as a precautionary principle for public health.
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Butyrate has been used extensively as a feed additive to improve gut health and to decrease Salmonella colonization in poultry. Salmonella mainly colonizes the ceca so butyrate concentrations should be increased in this gut segment. Discrepancies on the effects of butyrate on Salmonella colonization, described in the scientific literature, could thus be due to butyrate release location effects. In this study, newly developed butyrate formulations were evaluated for their effect on cecal butyrate concentrations and on colonization by Salmonella Enteritidis. In a first trial, broilers were randomly allocated to 7 dietary treatment groups with formulations based on different approaches to modify the butyrate release profile: release from wax matrices based on diffusion/erosion; micropellets supposedly release butyrate around pH 7 in the colon; tributyrin is based on the hydrolysis of esters in the small intestine. Fat-protected butyrate was included as a reference, because of its known effect on reduction of Salmonella colonization. Four days after infection, the number of cfu Salmonella per g cecal content and spleen were determined. Butyrate formulations in a wax matrix significantly reduced the Salmonella colonization in cecal content. In a second trial, wax and fat-protected butyrate treatments were replicated and results from the first trial were confirmed. Compared to the control group a higher proportion of butyrate concentration was observed in ceca for those groups with reduced Salmonella colonization. This was associated with a beneficial shift in the cecal microbiota. In conclusion, formulations that increase cecal butyrate concentrations are superior in protecting against Salmonella Enteritidis colonization.
Chapter
This introductory chapter is an overview of targets for antimicrobial action and mechanisms of bacterial resistance combined with information on the nature of antibacterial drugs, their classification, and their usage in animals. On the basis of the target microorganism, drugs are classified as antiviral, antibacterial, antifungal, and antiparasitic. There are numerous definitions of bacterial resistance, which are based on different criteria (genetic, biochemical, microbiological, and clinical) and do not necessarily overlap. The two most commonly used definitions are based on microbiological (in vitro resistance) and clinical (in vivo resistance) criteria. Multiresistant clinical strains of Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica serovar Enteritidis, and Staphylococcus aureus display in vivo mutation rates that are 1,000‐fold higher than in other members of these species. There are important differences in the use of antibacterial agents in humans and animals, in particular food animals. Bacteria have developed various mechanisms to neutralize the action of antibacterial agents. The most widespread are enzymatic drug inactivation, modification or replacement of the drug target, active drug efflux, and reduced drug uptake.