In vitro Antibacterial Efficacy of Non-Antibiotic Growth Promoters in Poultry Industry

Yupingfeng polysaccharide promote the growth of chickens via regulating gut microbiota

Introduction

Yupingfeng polysaccharide (YPF-P) is the main substance of alcohol deposition in Yupingfeng powder, which has many biological functions such as enhancing immunity, repairing intestinal barrier and enhancing antioxidant ability. This study employed in vitro growth-promoting drug feed additives and animal experiments to comprehensively evaluate the use of YPF-P in broiler production.

Methods

A total of 1,296 151 days-old Qingyuan Partridge chickens were randomly divided into four groups with six replicates and 54 hens per replicate: the control group was fed basal diet, and the experimental groups were fed diets supplemented with 4 g/kg, 8 g/kg, and 12 g/kg YPF-P for 14 days. Broilers were weighed before and at the end of the experiment to calculate total weight gain (GW), average daily gain (ADG), and feed compensation. At the end of the experiment, six chickens from each group were randomly selected for subwing vein blood sampling, which was used to measure serum biochemical indicators GHRH, GH, and IGF-1 by ELISA method. Randomly select chickens from control group and 8 g/kg group for slaughter, and cecal contents were collected for 16S high-throughput sequencing.

Results

Dietary supplementation of 8 g/kg YPF-P can significantly increase the final body weight, total weight gain, average daily gain and decrease the feed to gain ratio of chickens. During 151-165 days, serum IGF-1 concentrations increased significantly (p < 0.05). There were no significant changes in serum GH concentration (p > 0.05). In terms of gut microbiota, there was no significant difference between control group and test group in Shannon index and Simpson index. Compared with the control group,the addition of 8 g/kgYPF-P significantly increased the abundance of Firmicutes and significantly decreased the abundance of Bacteroides at the phylum level.At the genus level, the relative abundance of unclassified_Oscillospiraceae was significantly increased and the unclassified_Muribaculaceae, uncultured_Bacteroidales_bacterium, Lactobacillus, Alloprevotella, Ligilactobacillus, Prevotellaceae_UCG_001, and unclassified_Atopobiaceae was significantly decreased.

Conclusion

The above results showed that adding 8 mg/kg of YPF-P could increase the average daily gain of Qingyuan Partridge chickens, reduce the ratio of feed to meat, and affect the distribution proportion of intestinal microflora in chickens to some extent.

The induced and intrinsic resistance of Escherichia coli to sanguinarine is mediated by AcrB efflux pump

IMPORTANCE

The use of plant extracts is increasing as an alternative to synthetic compounds, especially antibiotics. However, there is no sufficient knowledge on the mechanisms and potential risks of antibiotic resistance induced by these phytochemicals. In the present study, we found that stable drug resistant mutants of E. coli emerged after repetitive exposure to sanguinarine and demonstrated that the AcrB efflux pump contributed to the emerging of induced and intrinsic resistance of E. coli to this phytochemical. Our results offered some insights into comprehending and preventing the onset of drug-resistant strains when utilizing products containing sanguinarine.

Comparative effects of medium-chain fatty acids or phytobiotics-based feed additives on performance, caecum microbiota, volatile fatty acid production and intestinal morphology of broilers

Antibiotic growth promoters have been utilized in broiler nutrition to alleviate the negative effects of the pathogenic microbes to promote performance. However, after the prohibition of antibiotics because of the increasing disclosure related to public health issues, various products have been developed as alternatives. This study was carried out to determine the effects of medium-chain fatty acids (MCFAs) or phytobiotics (essential oils [EOs] and alkaloids [ALKs]), blended feed additives on the growth performance, jejunum histomorphology, and cecal microbiota of broiler chickens. A total of 765 male Ross 308 chicks were randomly distributed into 5 experimental groups, each having 9 replicates with 17 chicks. The experimental procedures were as follows: a control group without supplementation (T1); control group+ MCFAs and EOs blend (T2); control group+ different EOs blend (T3); control group+ ALK sanguinarine (T4); and control group+ EOs and ALK piperine mixture (T5). The results showed that, broilers fed with MCFAs blended with EOs had significantly greater body weight gain during overall period in comparision to the control and T3 groups. Further, only MCFAs blended with EOs group significantly improved jejnum morphology in comparison with the control group (p ≤ 0.05). Besides, the MCFAs blended with EOs group significantly elevated propionate, acetate and butyrate concentration, and decreased the concentration of branch chain fatty acids in caecum (p ≤ 0.05). The results indicated that, the combination of MCFAs and EOs seems to have improvement effects and could be preferred as an efficient feed additive in broiler production.

Recombinant Lactococcus lactis Expressing Human LL-37 Prevents Deaths from Viral Infections in Piglets and Chicken

Novel antibiotic substitutes are increasingly in demand in the animal husbandry industry. An oral recombinant Lactococcus lactis (L. lactis) expressing human LL-37 (oral LL-37) was developed and its safety and antiviral effectiveness in vivo was tested. In addition to impairing liposome integrity, LL-37 polypeptide from recombinant L. lactis could prevent the host cell infection by a variety of viruses, including recombinant SARS, SARS-CoV-2, Ebola virus, and vesicular stomatitis virus G. Subchronic toxicity studies performed on Sprague-Dawley rats showed that no cumulative toxicity was found during short-term intervention. Oral LL-37 treatment after the onset of fever could reduce mortality in piglets infected with porcine reproductive and respiratory syndrome virus. Moreover, body weight gain of piglets receiving treatment was progressively restored, and nucleic acid positive rebound was not undetected after discontinuation. Oral LL-37 consistently increased the lifespan of chickens infected with Newcastle viruses. These findings suggested a potential use of recombinantly modified microorganisms in veterinary medicine.

Sanguinarine Exhibits Antiviral Activity against Porcine Reproductive and Respiratory Syndrome Virus via Multisite Inhibition Mechanisms

Porcine reproductive and respiratory syndrome virus (PRRSV), the etiological agent of PRRS, is prevalent worldwide, causing substantial and immense economic losses to the global swine industry. While current commercial vaccines fail to efficiently control PRRS, the development of safe and effective antiviral drugs against PRRSV is urgently required. Alkaloids are natural products with wide pharmacological and biological activities. Herein, sanguinarine, a benzophenanthridine alkaloid that occurs in many plants such as Macleaya cordata, was demonstrated as a potent antagonist of PRRSV. Sanguinarine attenuated PRRSV proliferation by targeting the internalization, replication, and release stages of the viral life cycle. Furthermore, ALB, AR, MAPK8, MAPK14, IGF1, GSK3B, PTGS2, and NOS2 were found as potential key targets related to the anti-PRRSV effect of sanguinarine as revealed by network pharmacology and molecular docking. Significantly, we demonstrated that the combination of sanguinarine with chelerythrine, another key bioactive alkaloid derived from Macleaya cordata, improved the antiviral activity. In summary, our findings reveal the promising potential of sanguinarine as a novel candidate for the development of anti-PRRSV agents.

In Vitro Evaluation of Antimicrobial Effect of Phytobiotics Mixture on Salmonella spp. Isolated from Chicken Broiler

Background: The identification of natural antibacterial agents from various sources that can act effectively against disease-causing foodborne bacteria is one of the major concerns throughout the world. In the present study, a unique phytobiotics mixture containing thymol, menthol, linalool, trans-anethole, methyl salicylate, 1,8-cineole, and p-cymene was evaluated for antibacterial activity against selected strains of Salmonella spp. Results: The phytobiotics mixture was effective against Salmonella enterica subsp. enterica serovars Enteritidis, Typhimurium, and Kentucky. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of this unique mixture for these three pathogens were 1:256. Among these three strains, one S. Kentucky presented the most extensive resistance profiles to 18 antibiotics belonging to 5 classes of antibiotics. One of S. Typhimurium presents extensive resistance profiles to 14 antibiotics belonging to 5 classes of antibiotics. Conclusions: The results suggest that the phytobiotics mixture used in the experiment can be used as a strong natural antibacterial agent against Gram-negative foodborne pathogens such as S. Typhimurium, S. Kentucky, and S. Enteritidis. This is a preliminary analysis of the effectiveness of a phytobiotic product in an in vitro model, which may be the starting point for further studies, including in vivo animal models.

Synergistic Interaction Between Paired Combinations of Natural Antimicrobials Against Poultry-Borne Pathogens

Natural antimicrobials (NAM) are promising candidates for the successful control of poultry-borne bacteria, carrying potent antimicrobial activity (AMA) against a wide range of multidrug-resistant pathogens. Individual activities of carvacrol, eugenol, trans-cinnamaldehyde, oregano, and thymol, along with the combined activity of paired compounds, were examined using broth microdilution and checkerboard techniques. The characteristic interactions between the compounds were calculated using an improved method, based on combination index (CI) values. The bacteria examined herein were selected due to their known genetic resistance to at least one antibiotic. Our results indicated that thymol was most effective, exhibiting the lowest minimum inhibitory concentration (MIC) value against Salmonella pullorum, Escherichia coli, and Klebsiella pneumoniae, establishing the order of antimicrobial efficacy as: thymol > oregano > carvacrol > trans-cinnamaldehyde > eugenol. In the interaction study, the paired combination of carvacrol and thymol showed synergistic effects and was highly effective in reducing the antibiotic resistance of all the evaluated pathogens. Notably, all CI values were <1.0 in evaluations of S. pullorum, indicating the absence of antagonism between eugenol and thymol (or oregano). In K. pneumoniae, majority of CI values, which had a few concentration points, were smaller than 1.0, indicating a synergistic effect between eugenol and carvacrol (oregano or thymol), and trans-cinnamaldehyde and carvacrol. In E. coli, apart from some concentration points, some CI values were smaller than 1.0, demonstrating a synergistic effect between eugenol and carvacrol, and thymol and carvacrol (eugenol or oregano). It is therefore of great significance to investigate and illuminate the minimal effect concentration of these five components when they are used in combination as feed additives. Moreover, the improved evaluation method of this study provides a precise and extensive means to assess the synergistic effects of NAM.

Potential role of important nutraceuticals in poultry performance and health - A comprehensive review

Antibiotics use in poultry as a growth promoter leads to the propagation of antibiotic-resistant microorganisms and incorporation of drug residues in foods; therefore, it has been restricted in different countries. There is a global trend to limit the use of antibiotics in the animal products. Prevention of the antibiotics use in the poultry diets led to the reduction in the growth performance. Consequently, there is a high demand for natural substances that lead to the same growth enhancement and beneficially affect poultry health. These constituents play essential roles in regulating the normal physiological functions of animals including the protection from infectious ailments. Nutraceuticals administration resulted beneficial in both infectious and noninfectious diseases. Being the natural components of diet, they are compatible with it and do not pose risks associated with antibiotics or other drugs. Nutraceuticals are categorized as commercial additives obtained from natural products as an alternative feed supplement for the improvement of animal welfare. This group includes enzymes, synbiotics, phytobiotics, organic acids and polyunsaturated fatty acids. In the present review, the summary of various bioactive ingredients that act as nutraceuticals and their mode of action in growth promotion and elevation of the immune system has been presented.

Effects of phytobiotic feed additives on growth traits, blood biochemistry, and meat characteristics of broiler chickens exposed to Salmonella typhimurium

Because of concerns over the use of antibiotics in poultry feed, this study was designed to determine the effectiveness of phytobiotic supplementation as an alternative to antibiotic use based on growth performance and meat characteristics of broilers exposed to Salmonella typhimurium. The effects of an antibiotic and 3 phytobiotic feed additives (PFA), Mix-Oil Mint (MO_mint), Mix-Oil Liquid (MO_liq), and Sangrovit Extra (Sang_ext), were compared. At day of age, 280 Ross chicks were randomly allocated into 6 treatments. At 15 d, all chicks except negative control were exposed to S. typhimurium. The offered 6 diets were as follows: T1, negative control; T2, infected with S. typhimurium; T3, infected + avilamycin (0.1 g/kg); T4, infected + MO_mint (0.2 g/kg); T5, infected + plant extract in liquid form MO_liq (0.25 mL/L); and T6, infected + Sang_ext (0.15 g/kg). During the cumulative starter period, PFA improved performance over that of the control, and the food conversion ratio (FCR) was lower for T3 and T5 compared with T1 (P < 0.05). During the cumulative finisher period (15–35 d), a lower body weight gain (P < 0.01) was observed in T2. T1 had the best FCR and production efficiency factor, but they were not significantly different from those of T3, T4, and T6 (P < 0.001). At 35 d, T1 and T4 had a higher breast percentage as compared with those of T2 (P < 0.05). Blood glucose decreased significantly (P > 0.05) in T2 and T5 compared with that in T1 and T4. Alanine transaminase concentration decreased significantly (P < 0.01) in T4 and T5 compared with that in T1, T2, and T3. Treatments had significant effects on breast temperature and pH (P < 0.001). A significant decrease in the myofibril fragmentation index occurred in T1 and T6. Hardness and chewiness were influenced by treatments (P < 0.05). In conclusion, dietary supplementation with PFA could effectively compare with that of antibiotic avilamycin in the maintenance of growth performance and improvement in meat characteristics of broilers challenged with S. typhimurium.