How did antibiotic growth promoters increase growth and feed efficiency in poultry?

Role of phytogenic feed additives on animal product quality and acceptance-a review

Antibiotic feed additives are frequently added to animal diets at subtherapeutic dosages in order to boost feed conversion and accelerate growth. These growth promoters can potentially to compromise the therapeutic efficacy of antimicrobial agents used in humans and animals by fostering the emergence and spread of antibiotic-resistant genes. Consumers are becoming more aware of the harmful consequences of bacteria that are resistant to antibiotics. There is a growing body of research on substitute growth promoters; at the moment, the goals are to increase growth rates and decrease the use of veterinary antibiotics in agriculture. Potential substitutes for antibiotic feed additives include phytogenic feed additives and compounds derived from plants. Phytogenic feed additives (PFA) including herbs, spices, essential oils and other plant extracts enhances zootechnical and animal health parameters, lowers emissions of ammonia and odors, enhances the utilization of amino acids and nutrients, and improves the quality of the carcass and meat. This review examines how phytogenic feed additives supplementation affects animal product quality and acceptability by consumers.

Effects of antibiotics on chicken gut microbiota: community alterations and pathogen identification

The extensive use of antibiotics in animal husbandry, either for therapeutic purposes or as growth promoters, has raised significant concerns about their effects on poultry. However, when antibiotics are used as therapeutic agents, their impact on the gut microbiota of poultry remains unknown. This study aimed to address this gap by simulating therapeutic application of six frequently used antibiotics (lincomycin hydrochloride, gentamicin sulfate, florfenicol injection, benzylpenicillin potassium, ceftiofur sodium, and enrofloxacin infection) and investigated their effects on the composition and structure of poultry gut microbiota. Single-molecule real-time 16S rRNA sequencing was performed to analyze fecal samples collected from chickens treated with each antibiotic to assess the impact of antibiotic exposure on gut community diversity and dominant microbial species. Although the results demonstrated that antibiotic exposure reduced gut microbiota diversity and disrupted community stability, the impacts of different antibiotics differed considerably, specifically in the number of ASVs. Notably, the dominant bacterial phyla-Pseudomonadota and Bacillota-was largely consistent across different antibiotic exposures, except 11 days after gentamicin sulfate exposure. Moreover, six third-category pathogens were identified in fecal samples, namely, Shigella boydii, Escherichia coli, Shigella flexneri, Salmonella enterica, Corynebacterium bovis, Proteus mirabilis. Of these, three strains of Corynebacterium bovis were identified as potential novel pathogenic bacteria. These findings demonstrate the critical importance of rational antibiotics use in animal husbandry. This study provides a scientific basis for improving current antibiotics use in the treatment and prevention of poultry diseases, advancing the standardization and precision of antibiotic usage.

Comparative meta-analysis of prevalence and molecular features of high-priority Enterococcus faecium and E. faecalis from the guts of food-producing and wild birds

RESEARCH HIGHLIGHTS

Vancomycin, ampicillin, and linezolid resistance in E. faecium and E. faecalis are considered high-priority public health concerns.This is a meta-analysis of high-priority E. faecium and E. faecalis from gut samples of birds.Food-producing birds had significantly higher frequency of priority E. faecium and E. faecalis than wild birds.Vancomycin resistance in E. faecium and E. faecalis exists more frequently than linezolid resistance.E. faecium has a higher capacity to acquire ampicillin and vancomycin resistance than E. faecalis.Genetically related human-adapted vancomycin- and linezolid-resistant strains were identified in food-producing and wild birds.

Effects of Environmentally Friendly Aquaculture Chamber Coatings on Enzyme Activities, Histology, and Transcriptome in the Liver of Larimichthys crocea

Aquaculture vessels have emerged as a sustainable alternative to traditional offshore aquaculture. However, the biological impacts of protective coatings used for vessel interiors are still poorly understood. This study assessed acute stress responses of Larimichthys crocea to epoxy-based aquaculture coatings using actual culture (1-fold) and high-exposure (80-fold) concentrations. Liver analyses included antioxidant enzymes, histopathology, and transcriptomics over 12-96 h. Firstly, the effect of the 80-fold concentration group on the activities of catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) was more significant in the liver of L. crocea compared to the 1-fold concentration group. Similarly, histological observations revealed that the 80-fold concentration group produced more significant pathological changes in the liver than the 1-fold concentration group, including hepatocyte damage and vacuolization. Subsequently, through high-throughput sequencing, a total of 714.02 million clean reads were obtained, with 693.71 million of these reads successfully mapped onto the reference genome of L. crocea, identifying 13,709 differentially expressed genes (DEGs). KEGG pathway enrichment analysis showed that many DEGs following coating-treated were involved in protein processing in endoplasmic reticulum, oxidative phosphorylation, cytokine-cytokine receptor interaction, FoxO signaling pathway, and toll-like receptor signaling pathway. Finally, fifteen DEGs were selected for quantitative real-time PCR (qRT-PCR) analysis, and the results showed a significant correlation with RNA-seq results, verifying the reliability and accuracy of the high-throughput sequencing data. This study preliminarily revealed the stress responses induced by aquaculture vessel coatings in L. crocea and provided fundamental data into the scientific use of coatings on aquaculture vessels.

Is use of antimicrobial growth promoters linked to antimicrobial resistance in food-producing animals? A systematic review

Antimicrobial resistance (AMR) poses a global threat to the health of humans, animals and plants, as well as the environment. In recent years, attention has increasingly focused on the role of antimicrobials as growth promoter (AGPs) in livestock. While the mechanism of action of AGPs is still poorly understood, mounting evidence suggests a link between AGP use and AMR. Consequently, several countries and regions have restricted/banned AGP use in livestock. However, such efforts encounter political, financial, social, and cultural challenges. This systematic review aims to investigate the impact of AGP use on AMR in food-producing animals and focused on the emergence of phenotypic resistance in Escherichia coli isolated from livestock exposed to AGPs. Overall, 7000 studies were screened at title, abstract and full text; from these, 10 were deemed eligible for inclusion in this review. Among the 10 selected studies, seven noted significant increase of AMR associated with AGP use. Significantly increased resistance levels to Highest Priority Critically Important Antimicrobials for human health such as ceftiofur, cefotaxime, ciprofloxacin, and nalidixic acid were observed among other antimicrobials. However, the studies revealed high risk of bias underscoring the need for further research. This review provides a deeper understanding of the consequences of AGP use and occurrence of AMR. It highlights the need for implementing efficient surveillance systems and fostering research into suitable alternatives to AGPs. A shift to sustainable husbandry practices including responsible AMU while safeguarding animal health, productivity and farmers' livelihoods are essential for successful policy implementation.

Surveillance of Drug Residue Profiles in Gallus gallus domesticus (Silkie Chickens) in Taiwan

Veterinary drugs are extensively utilized in poultry farming for purposes such as disease prevention, disease treatment, and feed efficiency enhancement. However, the application of these drugs can lead to unacceptable residues in edible products. This study aimed to investigate the residue profiles of veterinary drugs in silkie chickens. A total of 130 chicken samples were collected from two major retail markets in Taiwan between 2022 and 2024. The analysis of drug residues was conducted using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The overall detection rate of drug residues was 57.7%, and most of these residues were found to be below the maximum residue limits. Among the detected drugs, trimethoprim was the most prevalent, followed by nicarbazin, robenidine, decoquinate, diclazuril, and sulfamonomethoxine. Notably, there was a 31.4% chance that different samples from the same flock would yield varying results. Furthermore, a positive correlation was observed between drug residues and sample weight. In conclusion, this study provides valuable epidemiological data on drug residue profiles in silkie chickens in Taiwan. In the future, it is highly recommended that veterinary drug residues be continuously monitored, and food product sampling protocols be adjusted annually to ensure ongoing compliance with safety standards and protect consumer health.

Positive impact of early-probiotic administration on performance parameters, intestinal health and microbiota populations in broiler chickens

Minimizing the utilization of antibiotics in animal production is crucial to prevent the emergence of antimicrobial resistances. Thus, research on alternatives is needed to maintain productivity, sustainability, and animal health. To gain a comprehensive understanding of probiotics' modes of action on performance, intestinal microbiota, and gut health in poultry, 3 probiotic strains (Enterococcus faecalis CV1028 [EntF], Bacteroides fragilis GP1764 [BacF], and Ligilactobacillus salivarius CTC2197 [LacS]) were tested in 2 in vivo trials. Trial 1 comprised of a negative control group fed basal diet (BD) and 3 treatment groups that received BD with EntF, BacF and LacS. Trial 2 included a negative control group, a positive control group with Zinc-Bacitracin as antibiotic growth promoter (AGP), and 2 groups treated with a blend of probiotics (EntF+BacF+LacS) during 0 to 10 or 0 to 35 d, respectively. Wheat-soybean-rye based diets without exogenous enzymes were used as a challenge model to induce intestinal mild- or moderate-inflammatory process in the gut. In Trial 1, individually administered probiotics improved FCR at 8 d compared to Control, but these positive effects were lost in the following growing periods probably due to the high grade of challenging diet and a too low dose of probiotics. In Trial 2, both Probiotic treatments, administered only 10 or 35 d, significantly improved FCR to the same extent as of the Antibiotic group at the end of the trial. Although the performance between antibiotic and probiotic mixture showed similar values, microbiota analysis revealed different microbial composition at 7 d, but not at 21 d. This suggests that modes of action of the AGP and the tested probiotic blend differ on their effects on microbiome, and that the changes observed during the first days' posthatch are relevant on performance at the end of the study. Therefore, the probiotics administration only during the first 10 d posthatch was proven sufficient to induce similar performance improvements to those observed in birds fed antibiotic growth promoters throughout the whole experimental trial.

Effects of Guanidine Acetic Acid on the Growth and Slaughter Performance, Meat Quality, Antioxidant Capacity, and Cecal Microbiota of Broiler Chickens

The objective of this research was to assess the impact of guanidine acetic acid (GAA) on the growth performance, slaughter outcomes, meat quality, antioxidant capacity, and cecal microbiota of broiler chickens. A total of 128 Arbor Acres broilers were randomly divided into two experimental groups. One group served as the control and was provided with a standard diet, whereas the group treated with GAA received a diet enhanced with 400 mg/kg of GAA. The duration of the experiment was 42 days. Measurements for growth performance, serum biochemical parameters, and antioxidant capacity were conducted both during and at the conclusion of the study, while assessments of slaughter performance and meat quality were carried out solely at the end. Notable differences were observed in terms of growth performance, blood biochemistry, and metabolic parameters between the control and GAA-treated groups (p < 0.05). Hence, these findings imply that dietary GAA supplementation can favorably affect growth, carcass quality, biochemical indicators, and antioxidant capacity in broiler chickens.

The underlying mechanisms of oxytetracycline degradation mediated by gut microbial proteins and metabolites in Hermetia illucens

Hermetia illucens larvae can enhance the degradation of oxytetracycline (OTC) through its biotransformation. However, the underlying mechanisms mediated by gut metabolites and proteins are unclear. To gain further insights, the kinetics of OTC degradation, the functional structures of gut bacterial communities, proteins, and metabolites were investigated. An availability-adjusted first-order model effectively evaluated OTC degradation kinetics, with degradation half-lives of 4.18 and 21.71 days for OTC degradation with and without larval biotransformation, respectively. Dominant bacteria in the larval guts were Enterococcus, Psychrobacter, Providencia, Myroides, Enterobacteriaceae, and Lactobacillales. OTC exposure led to significant differential expression of proteins, with functional classification revealing involvement in digestion, transformation, and adaptability to environmental stress. Upregulated proteins, such as aromatic ring hydroxylase, acted as oxidoreductases modifying the chemical structure of OTC. Unique metabolites, aclarubicin and sancycline identified were possible OTC metabolic intermediates. Correlation analysis revealed significant interdependence between gut bacteria, metabolites, and proteins. These findings reveal a synergistic mechanism involving gut microbial metabolism and enzyme structure that drives the rapid degradation of OTC and facilitates the engineering applications of bioremediation.

Impact of Lactobacillus- and Bifidobacterium-Based Direct-Fed Microbials on the Performance, Intestinal Morphology, and Fecal Bacterial Populations of Nursery Pigs

Weaning is a critical stage in the swine production cycle, as young pigs need to adjust to sudden and dramatic changes in their diet and environment. Among the various organ systems affected, the gastrointestinal tract is one of the more severely impacted during this transition. Traditionally, challenges at weaning have been managed by prophylactic use of antibiotics, which not only provides protection against diarrhea and other gut dysfunction but also has growth-promoting effects. With banning or major restrictions on the use of antibiotics for this purpose, various alternative products have been developed as potential replacements, including direct-fed microbials (DFMs) such as probiotics and postbiotics. As their efficiency needs to be improved, a continued effort to gain a deeper understanding of their mechanism of action is necessary. In this context, this report presents a study on the impact of a Lactobacillus-based probiotic (LPr) and a Bifidobacterium-based postbiotic (BPo) when added to the diet during the nursery phase. For animal performance, an effect was observed in the early stages (Day 0 to Day 10), as pigs fed diets supplemented with either DFMs were found to have higher average daily feed intake (ADFI) compared to pigs fed the control diet (p < 0.05). Histological analysis of intestinal morphology on D10 revealed that the ileum of supplemented pigs had a higher villus height/crypt depth ratio (p < 0.05) compared to controls, indicating a benefit of the DFMs for gut health. In an effort to further explore potential mechanisms of action, the effects of the DFMs on gut microbial composition were investigated using fecal microbial communities as a non-invasive representative approach. At the bacterial family level, Lactobacillaceae were found in higher abundance in pigs fed either LPr (D10; p < 0.05) or BPo (D47; p < 0.05). At the Operational Taxonomic Unit (OTU) level, which can be used as a proxy to assess species composition, Ssd-00950 and Ssd-01187 were found in higher abundance in DFM-supplemented pigs on D47 (p < 0.05). Using nucleotide sequence identity, these OTUs were predicted to be putative strains of Congobacterium massiliense and Absicoccus porci, respectively. In contrast, OTU Ssd-00039, which was predicted to be a strain of Streptococcus alactolyticus, was in lower abundance in BPo-supplemented pigs on D47 (p < 0.05). Together, these results indicate that the DFMs tested in this study can impact various aspects of gut function.

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.