Bacteriophage and probiotics both enhance the performance of growing pigs but bacteriophage are more effective

Regulatory Landscape and the Potential of Bacteriophage Applications in the United States' Food Industry

Bacteriophages are promising tools for mitigating bacterial contamination because of their specificity for bacterial cells. The food industry can enhance food safety and quality by applying bacteriophages in various settings, from farms to ready-to-eat (RTE) products. Renewed interest has been driven by recent advancements in research and the increasing need for sustainable alternatives in food safety. However, understanding the regulatory requirements for using bacteriophages in food and agriculture in the United States is essential. These complex and varied regulations impact the approval and implementation of bacteriophage-based solutions. Addressing these regulatory requirements is crucial to ensure that bacteriophage applications comply with safety and legal standards. This review synthesizes the evolving regulatory framework governing bacteriophage use in the United States food industry, providing a clear understanding of the evaluation and approval processes, while highlighting recent changes and addressing challenges and opportunities for effective integration into food processing.

Evaluation of the Effect of Bacteriophages and Organic Acids as a Feed Additive to Reduce Salmonella enteritidis in Challenged Chickens

This study aimed to compare the effects of dietary supplementation of bacteriophage (BP) and acidifiers on performance, meat quality, morphology, and intestinal microbiota in chickens challenged and unchallenged with Salmonella enteritidis (SE) and also to investigate the possibility of replacing them in the diet with antibiotics. A total of 1760 male Ross (308) chicks were randomly assigned to 11 dietary treatments (8 pens/with 20 male chickens in each). Dietary treatments were as follows: SE-uninfected (negative control (NC), a basal diet without supplemention; NC+ 500 g/t BP (NBP1); NC+ 1000 g/t BP (NBP2); NC+ 300 mg/kg acidifier A (NAA); NC+ 300 mg/kg acidifier B (NAB)) and SE-infected (positive control (PC), a basal diet without supplemention; PC+ 40 mg/kg Antibiotic enrofloxacin (PA); PC+ 500 g/t BP (PBP1); PC+ 1000 g/t BP (PBP2); PC+ 3000 mg/kg acidifier A (PAA); PC+ 3000 mg/kg acidifier B (PAB)). At 13 D birds in challenged groups were orally gavaged with 1 mL bacterial suspension containing approximately 108 CFU Salmonella enterica. The results indicated that chicks challenged with SE impaired performance so that BWG and FI significantly decreased and FCR increased (p < 0.05). Diets containing a high dose of BP increased BW and improved FCR in challenged and unchallenged chickens. The quality of breast meat showed a decline in oxidation in chickens challenged with SE (p < 0.05). The inclusion of bacteriophage in the diet of chickens (1000 g/t) improved the L*, b*, and oxidation of meat. The use of bacteriophage and acidifier A in the diet significantly increased the Lactobacillus, and LAB count, especially in the challenged groups. The challenge of chickens with SE decreased the villus height and crypt depth in different parts of the small intestine (p < 0.05). The results of the present study suggested that 1000 g/t of BP probably improves chicken performance by increasing beneficial bacteria and decreasing pathogenic bacteria. Also, bacteriophage showed an improvement in the performance reduction of chickens with Salmonella infection. In addition, improved meat quality and beneficial changes in the microbiome and intestinal morphology indicate the effectiveness of BP as an alternative antibiotic growth promoter in broiler diets.

Intervention strategies for methicillin-resistant Staphylococcus aureus control in pig farming: a comprehensive review

Methicillin-resistant Staphylococcus aureus (MRSA) poses a serious public health threat due to its zoonotic potential and resistance to several antibiotic classes. Pig farming is recognized as a key reservoir for livestock-associated MRSA, necessitating effective intervention strategies to mitigate its prevalence. The objective of this narrative review was to summarize the current knowledge on the approaches to control MRSA on pig farms. The review process involved a comprehensive search across three electronic databases focusing on studies from 2000 to 2024 in both English and German.The review covers intervention measures including reduced antimicrobial use, cleaning and disinfection, air filtration, and bacteriophage application. Key findings indicate that, while interventions such as cleaning and disinfection and air filtration, can effectively reduce environmental MRSA loads, these measures are often insufficient for long-term control due to frequent recontamination, especially restocking with MRSA-positive animals. Eradication was shown to be effective in low-prevalence regions such as Norway, however, logistical and ethical challenges limit its feasibility in areas with high MRSA prevalence. Additional interventions, such as reduced antimicrobial use and sow washing, provided inconsistent results.Overall, the findings highlight the need for a multifaceted approach, combining several interventions tailored to regional MRSA prevalence, farm management practices, and available resources. Such an integrated strategy is essential for sustainable MRSA control in pig farming, thereby supporting the global One Health initiative aimed at mitigating antimicrobial resistance.

Genomic analysis, culturing optimization, and characterization of Escherichia bacteriophage OSYSP, previously studied as effective pathogen control on fresh produce

Advances in bacteriophage genome sequencing and regulatory approvals of some bacteriophages in various applications have renewed interest in these antibacterial viruses as a potential solution to persistent food safety challenges. Here, we analyzed in depth the genome of the previously studied Escherichia bacteriophage OSYSP (phage OSYSP), revealed its application-related characteristics, and optimized its enumeration techniques for facilitating industrial implementation. We previously sequenced phage OSYSP genome completely by combining results from Illumina Miseq and Ion Torrent sequencing platforms and completing the remaining sequence gaps using PCR. Based on the genomics analysis completed herein, phage OSYSP was confirmed as an obligate lytic phage of the Caudoviricetes class. The genome encodes 81 proteins of identifiable functions, including two endolysins and 45 proteins that support host-independent DNA replication, transcription, and repair. Despite its similarities to T5-like phages, unique genome arrangements confirm phage OSYSP's novelty. The genomic analysis also confirmed the absence of DNA sequences encoding virulence or antibiotic resistance factors. For optimizing phage detection and quantification in the conventional plaque assay, it was observed that decreasing the concentration of agar or agarose, when used as a medium gelling agent, increased phage recovery (p < 0.05), but using agarose resulted in smaller plaque diameters (p < 0.05). Phage OSYSP inactivated pathogenic and non-pathogenic strains of E. coli and some Salmonella enterica serovars, with more pronounced effect against E. coli O157:H7. Phage titers remained fairly unchanged throughout a 24-month storage at 4°C. Incubation for 30 min at 4°C-47°C or pH 4-11 had no significant detrimental effect (p > 0.05) on phage infectivity. In vitro application of phage OSYSP against E. coli O157:H7 EDL933 decreased the pathogen's viable population by >5.7-log CFU/mL within 80 min, at a multiplicity of infection as low as 0.01. The favorable genome characteristics, combined with improved enumeration methodology, and the proven infectivity stability, make phage OSYSP a promising biocontrol agent against pathogenic E. coli for food or therapeutic applications.

A review of bacteriophage and their application in domestic animals in a post-antibiotic era

Bacteriophages (phages for short) are the most abundant biological entities on Earth and are natural enemies of bacteria. Genomics and molecular biology have identified subtle and complex relationships among phages, bacteria and their animal hosts. This review covers composition, diversity and factors affecting gut phage, their lifecycle in the body, and interactions with bacteria and hosts. In addition, research regarding phage in poultry, aquaculture and livestock are summarized, and application of phages in antibiotic substitution, phage therapy and food safety are reviewed.

Investigation of the impact of multi-strain probiotics containing Saccharomyces cerevisiae on porcine production

A balanced intestinal microbiome controls intestinal bacterial diseases, helps regulate immunity, and digests and utilizes nutrients, ultimately having a positive effect on the productivity of industrial animals. Yeasts help in the digestion process by breaking down indigestible fibers and producing organic acids, vitamins, and minerals. In particular, polysaccharides such as beta-glucan and mannan-oligosaccharides, which are present in the cell wall of yeast, inhibit the adhesion of pathogens to the surface of the gastrointestinal tract and increase resistance to disease to help maintain and improve intestinal health. Among the yeast additives used in animal feed, Saccharomyces cerevisiae is one of the most commonly used probiotics. However, it does not naturally reside in the intestine, so if it is supplied in combination with other species of probiotics that can compensate for it, many benefits and synergies can be expected for pigs in terms of maintaining intestinal health such as supplementing the immune system and improving digestion. A number of previous studies have demonstrated that dietary complex probiotic supplementation has growth-promoting effects in pigs, suggesting that multiple strains of probiotics may be more effective than single strain probiotics due to their additive and synergistic effects. In practice, however, the effects of complex probiotics are not always consistent, and can be influenced by a variety of factors. Therefore, this review comprehensively examines and discusses the literature related to the effects of complex probiotics using Saccharomyces cerevisiae in pig production.

Effects of supplemental bacteriophage on the gut microbiota and nutrient digestibility of ileal-cannulated pigs

This study measured the potential changes of the microbiota in the gastrointestinal tract and energy and nutrient digestibility by supplemental bacteriophages in pigs. Twelve castrated male pigs (initial mean body weight = 29.5 ± 2.3 kg) were surgically cannulated using T-cannula. The animals were housed individually in pens equipped with a feeder and a nipple waterer. The pigs were allotted to 1 of 3 experimental diets in a quadruplicated 3 × 2 Latin square design with 3 experimental diets, 2 periods, and 12 pigs resulting in 8 replicates per diet. The 3 diets were a control mainly based on corn and soybean meal with no antibiotics or bacteriophages, a diet containing 0.1% antibiotics, and a diet containing 0.2% bacteriophages. On day 5 of the experimental period, feces were collected and on days 6 and 7, ileal digesta were collected. Genomic DNA for bacteria were extracted from the ileal digesta and feces and the V4 region of the 16S rRNA gene was amplified. The ileal and fecal digestibility of energy, dry matter, organic matter, crude protein, and fiber was unaffected by dietary antibiotics or bacteriophages. At the phylum level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Firmicutes (p = 0.059) and a lower proportion of Bacteroidetes (p = 0.099) in the ileal digesta samples compared with the control group with no difference between the antibiotic and bacteriophage groups. At the genus level, the supplemental antibiotic or bacteriophage tended to result in a higher proportion of Lactobacillus (p = 0.062) and a lower proportion of Bacteroides (p = 0.074) and Streptococcus (p = 0.088) in the ileal digesta compared with the control group with no difference between the antibiotic and bacteriophage groups. In the feces, supplemental antibiotics or bacteriophages reduced the proportion of Bifidobacterium compared with the control group (p = 0.029) with no difference between the antibiotic and bacteriophage groups. Overall, supplemental antibiotics and bacteriophages showed positive effect on the microbiota of in the ileal digesta without largely affecting energy or nutrient digestibility, with no differences between the antibiotic and bacteriophage groups in growing pigs.

Prospects and Challenges of Bacteriophage Substitution for Antibiotics in Livestock and Poultry Production

The overuse and misuse of antibiotics in the livestock and poultry industry has led to the development of multi-drug resistance in animal pathogens, and antibiotic resistance genes (ARGs) in bacteria transfer from animals to humans through the consumption of animal products, posing a serious threat to human health. Therefore, the use of antibiotics in livestock production has been strictly controlled. As a result, bacteriophages have attracted increasing research interest as antibiotic alternatives, since they are natural invaders of bacteria. Numerous studies have shown that dietary bacteriophage supplementation could regulate intestinal microbial composition, enhance mucosal immunity and the physical barrier function of the intestinal tract, and play an important role in maintaining intestinal microecological stability and normal body development of animals. The effect of bacteriophages used in animals is influenced by factors such as species, dose, and duration. However, as a category of mobile genetic elements, the high frequency of gene exchange of bacteriophages also poses risks of transmitting ARGs among bacteria. Hence, we summarized the mechanism and efficacy of bacteriophage therapy, and highlighted the feasibility and challenges of bacteriophage utilization in farm animal production, aiming to provide a reference for the safe and effective application of bacteriophages as an antibiotic alternative in livestock and poultry.

The current state of phage therapy in livestock and companion animals

In a global context, bacterial diseases caused by pathogenic bacteria have inflicted sustained damage on both humans and animals. Although antibiotics initially appeared to offer an easy treatment for most bacterial infections, the recent rise of multidrug-resistant bacteria, stemming from antibiotic misuse, has prompted regulatory measures to control antibiotic usage. Consequently, various alternatives to antibiotics are being explored, with a particular focus on bacteriophage (phage) therapy for treating bacterial diseases in animals. Animals are broadly categorized into livestock, closely associated with human dietary habits, and companion animals, which have attracted increasing attention. This study highlights phage therapy cases targeting prominent bacterial strains in various animals. In recent years, research on bacteriophages has gained considerable attention, suggesting a promising avenue for developing alternative substances to antibiotics, particularly crucial for addressing challenging bacterial diseases in the future.

Role of bacteriophages in shaping gut microbial community

Phages are the most diversified and dominant members of the gut virobiota. They play a crucial role in shaping the structure and function of the gut microbial community and consequently the health of humans and animals. Phages are found mainly in the mucus, from where they can translocate to the intestinal organs and act as a modulator of gut microbiota. Understanding the vital role of phages in regulating the composition of intestinal microbiota and influencing human and animal health is an emerging area of research. The relevance of phages in the gut ecosystem is supported by substantial evidence, but the importance of phages in shaping the gut microbiota remains unclear. Although information regarding general phage ecology and development has accumulated, detailed knowledge on phage-gut microbe and phage-human interactions is lacking, and the information on the effects of phage therapy in humans remains ambiguous. In this review, we systematically assess the existing data on the structure and ecology of phages in the human and animal gut environments, their development, possible interaction, and subsequent impact on the gut ecosystem dynamics. We discuss the potential mechanisms of prophage activation and the subsequent modulation of gut bacteria. We also review the link between phages and the immune system to collect evidence on the effect of phages on shaping the gut microbial composition. Our review will improve understanding on the influence of phages in regulating the gut microbiota and the immune system and facilitate the development of phage-based therapies for maintaining a healthy and balanced gut microbiota.

Anti-Bordetella bronchiseptica effects of targeted bacteriophages via microbiome and metabolic mediated mechanisms

Bordetella bronchiseptica poses a significant challenge in the context of respiratory infections, particularly in weanling pigs. In this study, we investigated the impact of a novel targeted bacteriophage in controlling B. bronchiseptica challenge (BBC) in an experimental design involving five distinct treatment groups: NC (no challenge), PC (BBC challenge), BF (108 pfu bacteriophage/kg diet + BBC), BN (2 × 107 pfu/day bacteriophage by nasal spray + BBC), and AT (antibiotic + BBC). The experiment was conducted for 2 weeks. The highest turbinate score was observed in the PC. The BF treatment showed higher plasma IL (interleukine)-1β and IL-6 compared with the BN and AT treatments. Plasma concentrations of IL-1β were increased in the BF pigs compared with the BN, AT, and NC. Among the BBC groups, the PC treatment exhibited a higher abundance of Staphylococcus. aureus and B. bronchiseptica in the lung. A lower S. aureus, Streptococcus. suis, and B. bronchiseptica colonization was detected in the AT compared with the BF and BN treatments. The BF showed lower plasma zonulin compared with the BN and AT. A higher plasma concentration of superoxide dismutase was observed in the BF and AT compared with PC and BN. The BN influenced the glycine, serine-threonine metabolism; glycerolipid metabolism; glyoxylate-dicarboxylate metabolism; and arachidonic acid metabolism compared with the NC. In conclusion, nasal-sprayed bacteriophage effectively controlled B. bronchiseptica infection, however, their efficiency was lower than the antibiotic.

Effect of a Bacillus-Based Probiotic on Performance and Nutrient Digestibility When Substituting Soybean Meal with Rapeseed Meal in Grower-Finisher Diets

The objective of the present study was to test the hypothesis of B. subtilis and B. licheniformis supplementation to a negative control diet in comparison to a standard control diet, had the potential to improve the performance and nutrient digestibility of growing-finishing pigs. For this purpose, 384 fattening pigs of 85 d of age were allotted to three treatments: a standard diet, a negative control (NC) diet (5% soybean meal replaced by 5% rapeseed meal), or a NC diet + probiotic. After reaching a body weight of approximately 110 kg, all animals going to the slaughterhouse (87% of total pigs) were selected to measure carcass quality. Moreover, the apparent total tract digestibility of protein was evaluated at the end of the grower period. The results of this study indicate that supplementation of the tested Bacillus-based probiotic significantly improved average daily gain (ADG, +14.6%) and Feed:gain ratio (F:G, -9.9%) during the grower phase compared to the NC diet. The improvement observed during the grower phase was maintained for the whole fattening period (ADG, +3.9%). Probiotic supplementation significantly improved the total apparent faecal digestibility of dry matter and crude protein in pigs at the end of the grower period. The improvements observed with the additive tested could indicate that supplementation of the Bacillus-based probiotic was able to counteract the lower level of crude protein and standardised ileal digestible amino acids in the NC diet by means of improved protein digestibility.

Effects of dietary supplementation of bacteriophage cocktail on health status of weanling pigs in a non-sanitary environment

BACKGROUND

The study evaluated the effects of bacteriophage cocktail (BP) and ZnO administered during weaning time for piglets exposed to a non-sanitary environment. The bacteriophages were designed to eliminate Escherichia coli (K88, K99 and F41), Salmonella (typhimurium and enteritidis), and Clostridium perfreingens (types A and C). Forty 21-day-old crossbreed piglets were assigned to four treatments, including the PC (sanitary environment), NC (non-sanitary environment), BP (NC plus 10⁸ pfu/kg BP), and ZO (NC plus 2,500 mg/kg ZnO). Piglets in the NC, BP and ZO were kept in a non-sanitary environment for 14 d, which was contaminated with the feces of infected pigs.

RESULTS

Pigs in the BP and ZO treatments had a higher final body weight compared with the NC. The NC treatment showed the highest concentration of inflammatory cytokines including interleukin (IL)-1β, IL-6 and tumor necrosis factor-α in the plasma. The administration of BP and ZO showed lower myeloperoxidase concentrations compared with the NC. The NC treatment showed a lower concentration of superoxide dismutase in serum compared with the PC. Among the treatments in non-sanitary environment, the NC treatment showed a higher concentration of malondialdehyde compared with the ZO. The PC treatment showed a lower concentration of butyric acid in the feces compared with the BP treatment. Among non-sanitary treatments, the villus height in the duodenum was greater in the BP and ZO compared with the NC. The lower abundance of Proteobacteria phylum was observed in the BP and PC treatments compared with the NC. The highest relative abundance of Eubacterium was recorded in the BP treatment. The abundance of Megasphaera and Schwartzia was higher in the NC pigs compared with the BP piglets. The abundance of Desulfovibrio was lower in the supplemented treatments (BP and ZO) compared with non-supplemented (NC and PC). The abundance of Cellulosilyticum genera was higher in the BP and ZO treatments rather than in the NC. The piglets in the NC treatment had the highest abundance of Escherichia-Shigella, followed by the PC and ZO treatments.

CONCLUSION

In conclusion, these results suggest that the supplementation of bacteriophage cocktail could effectively control Proteobacteria phylum, Clostridium spp. and coliforms population and mitigated the adverse influences of weaning stress in piglets.

Effects of Phage Cocktail, Probiotics, and Their Combination on Growth Performance and Gut Microbiota of Broiler Chickens

Phages, which are often used therapeutically, have begun to receive interest as alternatives to antibiotic growth promoters (AGPs) for enhancing chicken growth. Another option that has been extensively studied as a growth promoter in chickens is probiotics. To the best of our knowledge, there is currently no study available on the use of phages and probiotics in combination as potential feed additives for broiler chickens. Therefore, this study demonstrated the effects of a phage cocktail, probiotics, and their combination on the growth performance and gut microbiota of broiler chickens. A total of 288 one-day-old male Cobb 500 broilers were randomly allotted to one of six treatments in a completely randomised design. The treatments were (i) C (basal diet (BD) only), (ii) 1ϕ (BD + 0.1% phage cocktail), (iii) 2ϕ (BD + 0.2% phage cocktail), (iv) P (BD + 0.1% probiotic), (v) 1ϕP (BD + 0.1% phage cocktail + 0.1% probiotic), and (vi) 2ϕP (BD + 0.2% phage cocktail + 0.1% probiotic). The 1ϕP treatment had significantly (p < 0.05) better BW (35 days), BWG (22-35 days, 1-35 days), and FCR (1-21 days, 22-35 days, 1-35 days) compared to C. Unique gut microbiota diversity was also found between the ϕP (1ϕP and 2ϕP) and non-ϕP groups (C, 1ϕ, 2ϕ, and P) in ilea, particularly in the 35-day-old chickens. Microorganisms associated with short-chain fatty acid (SCFA) producers were significantly (p < 0.05) more present in the ϕP group than in the non-ϕP group. The predicted genes related to carbohydrate and amino acid metabolism were significantly upregulated in ϕP groups compared to non-ϕP groups. These genes were involved in the digestion and absorption of nutrients, as well as the production of energy. Our findings showed that the 1ϕP treatment could be a potential alternative to AGPs for poultry, as growth performance was enhanced, and gut microbiota was positively modulated.

Transplantation of fecal filtrate to neonatal pigs reduces post-weaning diarrhea: A pilot study

Post-weaning diarrhea (PWD) remains a major source of mortality and morbidity in swine production. Transplantation of bacteria-free filtrate of feces (fecal filtrate transplant, FFT) has shown gut protective effects in neonatal pigs, and early postnatal establishment of the gut microbiome is suggested to determine later stability and robustness of the gut. We, therefore, hypothesized that early postnatal transplantation of bacteria-free feces would have a protective effect against PWD. Using fecal filtrates derived from healthy lactating sows, we compared oral administration of fecal filtrate transplantation (FFT, n = 20) and saline (CON, n = 18) in newborn piglets. We assessed growth, diarrhea prevalence, blood parameters, organ measurements, morphology, and gut brush border enzymes and analyzed luminal bacterial composition using 16S rRNA gene amplicon sequencing. The two groups showed similar average daily gain (ADG) during the suckling period, whereas in the post-weaning period, a negative ADG was observed in both groups. While diarrhea was largely absent in both groups before weaning, there was a lower diarrhea prevalence on days 27 (p = 2.07*10−9), 28 (p = 0.04), and 35 (p = 0.04) in the FFT group relative to CON. At weaning on day 27, the FFT group had higher numbers of red blood cells, monocytes, and lymphocytes, while on day 35, i.e., 1 week after weaning, the two groups were similar regarding hematology. The biochemical profile was largely similar between FFT and CON on days 27 and 35, except for a higher level of alanine aminotransferase and a lower level of Mg in the FFT group. Likewise, organ weights relative to body weight were largely similar on day 35, albeit with a lower stomach weight and more colon content in FFT relative to CON. Gut mucosal percentage and mucosal enzyme activity were similar between the two groups on days 27 and 35. Gut bacterial composition was slightly different on day 35 but not on day 27. In conclusion, early postnatal administration of FFT, showed positive clinical effects in post-weaning pigs, albeit with subtle effects on the gut mucosa and microbiome. Prophylactic treatment with FFT may offer a means to reduce morbidity, yet larger studies are required to document effect size.

Effects of Heat-Killed Lactobacillus plantarum L-137 Supplementation on Growth Performance, Blood Profiles, Intestinal Morphology, and Immune Gene Expression in Pigs

In the present study, the effects of dietary heat-killed Lactobacillus plantarum L-137 (HK L-137) on the productive performance, intestinal morphology, and cytokine gene expression of suckling-to-fattening pigs were investigated. A total of 100 suckling pigs [(Large White × Landrace) × Duroc; 4.5 ± 0.54 kg initial body weight (BW)] were used and assigned to each of the four dietary treatments as follows: (1) a control diet with antibiotics as a growth promoter (AGP) from the suckling phase to the grower phase and no supplement in the finisher phases; (2) a control diet without antibiotics as a growth promoter (NAGP); (3) a control diet with HK L-137 at 20 mg/kg from the suckling phase to the starter phase and no supplement from the grower phase to the finisher phases (HKL1); and (4) a control diet with HK L-137 at 20 mg/kg from the suckling phase to the weaner phase, at 4 mg/kg from the starter phase to the finisher 1 phase, and no supplement in the finisher 2 phase (HKL2). During the weaner-starter period, the pigs fed on the AGP and HKL2 diets showed significantly higher weight gain and average daily gain (ADG) than those in the NAGP group (p < 0.05). The pigs in the AGP, HKL1, and HKL2 groups showed greater ADG than those in the NAGP groups (p < 0.05) throughout the grower-finisher period. The suckling pigs in the HKL1 and HKL2 groups showed a higher platelet count (484,500 and 575,750) than in the others (p < 0.05); however, there were no significant differences in the other hematological parameters among the treatment groups. The relative mRNA expression level of IFN- ß of the suckling and starter pigs were significantly higher in the HKL1 and HKL2 groups than in the others (p < 0.05), while the IFN-γ showed the highest level in the HKL2 suckling pigs (p < 0.05). These results demonstrate that a HK L-137 supplementation could stimulate the immune response in suckling and starter pigs and promote the growth performance in finishing pigs.

Swine enteric colibacillosis: Current treatment avenues and future directions

Enteric colibacillosis is a common disease in nursing and weanling pigs. It is caused by the colonization of the small intestine by enterotoxigenic strains of Escherichia coli (ETEC) that make use of specific fimbria or pili to adhere to the absorptive epithelial cells of the jejunum and ileum. Once attached, and when both the immunological systems and the gut microbiota are poorly developed, ETEC produce one or more enterotoxins that can have local and, further on, systemic effects. These enterotoxins cause fluid and electrolytes to be secreted into the intestinal lumen of animals, which results in diarrhea, dehydration, and acidosis. From the diversity of control strategies, antibiotics and zinc oxide are the ones that have contributed more significantly to mitigating post-weaning diarrhea (PWD) economic losses. However, concerns about antibiotic resistance determined the restriction on the use of critically important antimicrobials in food-producing animals and the prohibition of their use as growth promoters. As such, it is important now to begin the transition from these preventive/control measures to other, more sustainable, approaches. This review provides a quick synopsis of the currently approved and available therapies for PWD treatment while presenting an overview of novel antimicrobial strategies that are being explored for the control and treatment of this infection, including, prebiotics, probiotics, synbiotics, organic acids, bacteriophages, spray-dried plasma, antibodies, phytogenic substances, antisense oligonucleotides, and aptamers.

Review on Preventive Measures to Reduce Post-Weaning Diarrhoea in Piglets

In many countries, medical levels of zinc (typically as zinc oxide) are added to piglet diets in the first two weeks post-weaning to prevent the development of post-weaning diarrhoea (PWD). However, high levels of zinc constitute an environmental polluting agent, and may contribute to the development and/or maintenance of antimicrobial resistance (AMR) among bacteria. Consequently, the EU banned administering medical levels of zinc in pig diets as of June 2022. However, this may result in an increased use of antibiotic therapeutics to combat PWD and thereby an increased risk of further AMR development. The search for alternative measures against PWD with a minimum use of antibiotics and in the absence of medical levels of zinc has therefore been intensified over recent years, and feed-related measures, including feed ingredients, feed additives, and feeding strategies, are being intensively investigated. Furthermore, management strategies have been developed and are undoubtedly relevant; however, these will not be addressed in this review. Here, feed measures (and vaccines) are addressed, these being probiotics, prebiotics, synbiotics, postbiotics, proteobiotics, plants and plant extracts (in particular essential oils and tannins), macroalgae (particularly macroalgae-derived polysaccharides), dietary fibre, antimicrobial peptides, specific amino acids, dietary fatty acids, milk replacers, milk components, creep feed, vaccines, bacteriophages, and single-domain antibodies (nanobodies). The list covers measures with a rather long history and others that require significant development before their eventual use can be extended. To assess the potential of feed-related measures in combating PWD, the literature reviewed here has focused on studies reporting parameters of PWD (i.e., faeces score and/or faeces dry matter content during the first two weeks post-weaning). Although the impact on PWD (or related parameters) of the investigated measures may often be inconsistent, many studies do report positive effects. However, several studies have shown that control pigs do not suffer from diarrhoea, making it difficult to evaluate the biological and practical relevance of these improvements. From the reviewed literature, it is not possible to rank the efficacy of the various measures, and the efficacy most probably depends on a range of factors related to animal genetics and health status, additive doses used, composition of the feed, etc. We conclude that a combination of various measures is probably most recommendable in most situations. However, in this respect, it should be considered that combining strategies may lead to additive (e.g., synbiotics), synergistic (e.g., plant materials), or antagonistic (e.g., algae compounds) effects, requiring detailed knowledge on the modes of action in order to design effective strategies.

Potential Substitutes of Antibiotics for Swine and Poultry Production

Early of the last century, it was detected that antibiotics added to the animal feeds at low doses and for a long time can improve technical performances such as average daily gain and gain-to-feed ratio. Since then, the antibiotics have been used worldwide as feed additives for many decades. At the end of the twentieth century, the consequences of the uses of antibiotics in animal feeds as growth promoters were informed. Since then, many research studies have been done to find other solutions to replace partly or fully to antibiotic as growth promoters (AGPs). Many achievements in finding alternatives to AGPs in which probiotics and direct-fed microorganism, prebiotics, organic acids and their salts, feed enzymes, bacteriophages, herbs, spices, and other plant extractives (phytogenics), mineral and essential oils are included.

In vivo assessment of bacteriophages specific to multidrug resistant Escherichia coli on fecal bacterial counts and microbiome in nursery pigs

Escherichia coli is the most common cause of economic loss in swine industry. Nowadays, bacteriophages have been proven as good candidates for controlling bacterial infections. In this study, 6 phages were isolated and selected based on their high efficacy against 11 stains of E. coli isolated from diarrheal pigs. Six groups of weaned piglets were assigned (control, bacterial control (BC), two phage control (PC) and two phage treatment (PT) groups). Two titers (2 × 10⁹ PFU/animal and 2 × 10¹⁰ PFU/animal) of phage cocktails consisting of these phages were tested in the PC and PT groups via oral gavage at 24, 48, and 72 h against an E. coli cocktail (2 × 10⁹ CFU/animal) that was given to the piglets at 0, 12, 24, and 48 h of the trial. A significant reduction of fecal E. coli counts was observed in both PT groups from day 1 to 7 following the final phage dosage when compared to those of the BC group. Microbiomes in feces obtained 24 h after the final phage administration revealed phage therapy with both dosages could restore the gut's bacterial composition. Moreover, the given phage cocktails resulted in a significantly higher average daily gain of piglets during the first few weeks in both PC groups and the PT group receiving a higher phage dosage. These findings suggest that bacteriophages might be a potential alternative to antibiotics in the treatment of pathogens. In addition, they could also be utilized to improve pig growth performance.

Effects of a multi-strain Bacillus subtilis-based direct-fed microbial on immunity markers and intestinal morphology in diets fed to weanling pigs

The objective of this experiment was to evaluate the effects of a multi-strain Bacillus subtilis-based direct-fed microbial (DFM) on nursery pig health as indicated by intestinal mucosal and blood plasma immunological markers and intestinal morphology. Eighty pigs, of equal number of barrows and gilts (initial BW: 7.0 ± 0.60 kg), weaned at 21 ± 1 d of age were randomly allotted to sixteen pens, with five pigs per pen. Two dietary treatments were implemented, a basal control (CON) and a basal control plus DFM (CDFM). Both diets were corn, soybean meal, and distillers dried grains based and were formulated to meet or exceed all nutritional requirements (NRC, 2012) and manufactured on site. Diets were fed for 42 d. On d 21 and 42 of the experiment, one pig per pen was randomly selected and euthanized, with equal number of males and females represented. Blood samples were collected prior to euthanasia for assessment of plasma concentrations of immunoglobulin A (IgA) and intestinal fatty acid binding protein. Segments of the gastrointestinal tract including duodenum, jejunum, ileum, ascending and distal colon were removed for analysis of intestinal morphology, and levels of interleukin 6, interleukin 10 (IL-10), and tumor necrosis factor alpha. Jejunal villus height was greater in the CDFM pigs as compared with CON pigs (P = 0.02) and ascending colon crypt depth tended to be greater on d 21 (P = 0.10). Compared to CON, CDFM significantly increased overall plasma IgA (P = 0.03) (0.58 vs. 0.73 0.05 mg/mL, respectively), while it tended to increase plasma IgA (P = 0.06) on d 21 (0.34 vs. 0.54 ± 0.07 mg/mL, respectively) and tended to increase overall IL-10 (P = 0.10) in the jejunum (113 vs. 195 ± 35 pg/mL, respectively). Addition of a multi-strain Bacillus subtilis-based DFM may have an early benefit to nursery pig health status, observed through specific changes in morphology and both systemic and localized immunological markers.

Gastrointestinal Dynamics of Non-Encapsulated and Microencapsulated Salmonella Bacteriophages in Broiler Production

Simple Summary

Bacteriophages are viruses that kill targeted bacteria and could be used as a therapy against multidrug-resistant bacteria in animal production. Gastrointestinal tract conditions throughout the broiler production cycle might compromise the efficacy of bacteriophage oral administration against Salmonella. Microencapsulation of phages could protect and prevent the premature release of the bacteriophage, thereby allowing targeted delivery to the colonization site of Salmonella, the caecum. This study was designed to assess the optimal timing of the phage intervention over a 42-day production cycle and to compare microencapsulated (delivered in animal feed) and non-encapsulated phages (delivered through the drinking water) delivery along the gastrointestinal tract. Results of this study suggest that microencapsulation of the phages in a Eudragit^® L100 pH-responsive formulation allowed targeted delivery of the phage to the chicken caecum. Microencapsulation of phages administered orally through animal feed could be a promising method to control Salmonella in the field at any time during the animal rearing period.

Abstract

Bacteriophage therapy is being considered as a promising tool to control Salmonella in poultry. Nevertheless, changes in gastrointestinal tract environmental conditions throughout the production cycle could compromise the efficacy of phages administered orally. The main objectives of this study were to assess the optimal timing of the phage administration over a 42-day production cycle and to compare microencapsulated and non-encapsulated phages and the spatial and temporal dynamics of the phage delivery along the gastrointestinal tract. Phage FGS011 was encapsulated in the pH-responsive polymer Eudragit^® L100 using the process of spray drying. At different weeks of the chicken rearing period, 15 broilers were divided into three groups. Over a period of 24 h, group 1 received non-encapsulated phages (delivered through drinking water), group 2 received microencapsulated phages (incorporated in animal feed), and group 3 did not receive any phages. Microencapsulation was shown to enable efficient delivery of the bacteriophages to the animal gut and cecum throughout the animal rearing period. During the six weeks of application, the crop displayed the highest phage concentration for both phage delivery methods. The L100 based encapsulation offered significant protection to the phages from the harsh environmental conditions in the PV-Gizzard (not seen with phages administered in drinking water) which may help in the delivery of high phage doses to the cecum. Future Salmonella challenge studies are necessary to demonstrate the benefits of microencapsulation of phages using L100 formulation on phage therapy in field studies during the rearing period.

Bacteriophages: Combating Antimicrobial Resistance in Food-Borne Bacteria Prevalent in Agriculture

Through recent decades, the subtherapeutic use of antibiotics within agriculture has led to the widespread development of antimicrobial resistance. This problem not only impacts the productivity and sustainability of current agriculture but also has the potential to transfer antimicrobial resistance to human pathogens via the food supply chain. An increasingly popular alternative to antibiotics is bacteriophages to control bacterial diseases. Their unique bactericidal properties make them an ideal alternative to antibiotics, as many countries begin to restrict the usage of antibiotics in agriculture. This review analyses recent evidence from within the past decade on the efficacy of phage therapy on common foodborne pathogens, namely, Escherica coli, Staphylococcus aureus, Salmonella spp., and Campylobacter jejuni. This paper highlights the benefits and challenges of phage therapy and reveals the potential for phages to control bacterial populations both in food processing and livestock and the possibility for phages to replace subtherapeutic usage of antibiotics in the agriculture sector.

Reducing the Risk of Transmission of Critical Antimicrobial Resistance Determinants From Contaminated Pork Products to Humans in South-East Asia

Antimicrobial resistance (AMR) is a critical challenge worldwide as it impacts public health, especially via contamination in the food chain and in healthcare-associated infections. In relation to farming, the systems used, waste management on farms, and the production line process are all determinants reflecting the risk of AMR emergence and rate of contamination of foodstuffs. This review focuses on South East Asia (SEA), which contains diverse regions covering 11 countries, each having different levels of development, customs, laws, and regulations. Routinely, here as elsewhere antimicrobials are still used for three indications: therapy, prevention, and growth promotion, and these are the fundamental drivers of AMR development and persistence. The accuracy of detection of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) depends on the laboratory standards applicable in the various institutes and countries, and this affects the consistency of regional data. Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae are the standard proxy species used for indicating AMR-associated nosocomial infections and healthcare-associated infections. Pig feces and wastewater have been suspected as one of the hotspots for spread and circulation of ARB and ARG. As part of AMR surveillance in a One Health approach, clonal typing is used to identify bacterial clonal transmission from the production process to consumers and patients - although to date there have been few published definitive studies about this in SEA. Various alternatives to antibiotics are available to reduce antibiotic use on farms. Certain of these alternatives together with improved disease prevention methods are essential tools to reduce antimicrobial usage in swine farms and to support global policy. This review highlights evidence for potential transfer of resistant bacteria from food animals to humans, and awareness and understanding of AMR through a description of the occurrence of AMR in pig farm food chains under SEA management systems. The latter includes a description of standard pig farming practices, detection of AMR and clonal analysis of bacteria, and AMR in the food chain and associated environments. Finally, the possibility of using alternatives to antibiotics and improving policies for future strategies in combating AMR in a SEA context are outlined.

Phages in Food Industry Biocontrol and Bioremediation

Bacteriophages are ubiquitous in nature and their use is a current promising alternative in biological control. Multidrug resistant (MDR) bacterial strains are present in the livestock industry and phages are attractive candidates to eliminate them and their biofilms. This alternative therapy also reduces the non-desirable effects produced by chemicals on food. The World Health Organization (WHO) estimates that around 420,000 people die due to a foodborne illness annually, suggesting that an improvement in food biocontrol is desirable. This review summarizes relevant studies of phage use in biocontrol focusing on treatments in live animals, plants, surfaces, foods, wastewaters and bioremediation.

Phages in Food Industry Biocontrol and Bioremediation

Bacteriophages are ubiquitous in nature and their use is a current promising alternative in biological control. Multidrug resistant (MDR) bacterial strains are present in the livestock industry and phages are attractive candidates to eliminate them and their biofilms. This alternative therapy also reduces the non-desirable effects produced by chemicals on food. The World Health Organization (WHO) estimates that around 420,000 people die due to a foodborne illness annually, suggesting that an improvement in food biocontrol is desirable. This review summarizes relevant studies of phage use in biocontrol focusing on treatments in live animals, plants, surfaces, foods, wastewaters and bioremediation.

Effects of β-Mannanase and Bacteriophage Supplementation on Health and Growth Performance of Holstein Calves

Simple Summary

For sustainable animal agriculture, we need to find ways to increase growth efficiency without using feed antibiotics. Bacteriophages, which are only harmful to specific bacterial strains, have been suggested as a feed additive replacing antibiotics. β-mannanase, which degrades mannan, is known to promote nutrient digestibility, animal growth, or both, thus improving feed efficiency. The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. We assigned 36 pre-weaning male Holstein calves to one of four treatments with a 2 × 2 factorial arrangement: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and 0.1% β-mannanase supplementation in a starter on a dry matter basis. Compared to unsupplemented, the bacteriophage supplemented group showed a tendency to improve the survival rate without growth promotion. Supplementation of β-mannanase, on the other hand, increased the starter intake and the weekly body weight (BW) gain and tended to increase the final BW. Our study indicated that bacteriophage supplementation has a positive effect on survival rate, while β-mannanase supplementation improves growth performance in calves.

Abstract

The objective of this study was to evaluate the effects of dietary supplementation with bacteriophage and β-mannanase on health and growth performance in calves. Thirty-six pre-weaning male Holstein calves were randomly allocated to one of four dietary treatments with a 2 × 2 factorial arrangement: no supplementation, 0.1% β-mannanase, 0.1% bacteriophage, and both 0.1% bacteriophage and 0.1% β-mannanase supplementation in a starter on a dry matter basis. The experiment lasted from 2 weeks before weaning to 8 weeks after weaning. Twenty-two calves survived to the end of the experiment. No interaction was observed between the two different feed additives. The bacteriophage supplementation tended to increase the odds ratio of survival (p = 0.09). The number of Escherichia coli in feces significantly decreased by bacteriophage supplementation one week after weaning. β-mannanase supplementation increased the concentrate intake (p < 0.01) and tended to increase the final BW (p = 0.08). Analysis of repeated measures indicated β-mannanase supplementation increased weekly body weight gain (p = 0.018). We conclude that bacteriophage supplementation may have a positive effect on calf survival rate, while β-mannanase supplementation may increase the growth rate and starter intake by calves just before and after weaning.

Overcoming bacterial resistance to antibiotics: the urgent need – a review

The discovery of antibiotics is considered one of the most crucial breakthroughs in medicine and veterinary science in the 20th century. From the very beginning, this type of drug was used as a ‘miraculous cure’ for every type of infection. In addition to their therapeutic uses, antibiotics were also used for disease prevention and growth promotion in livestock. Though this application was banned in the European Union in 2006, antibiotics are still used in this way in countries all over the world. The unlimited and unregulated use of antibiotics has increased the speed of antibiotic resistance’s spread in different types of organisms. This phenomenon requires searching for new strategies to deal with hard-to-treat infections. The antimicrobial activity of some plant derivatives and animal products has been known since ancient times. At the beginning of this century, even more substances, such as antimicrobial peptides, were considered very promising candidates for becoming new alternatives to commonly used antimicrobials. However, many preclinical and clinical trials ended without positive results. A variety of strategies to fight microbes exist, but we are a long way from approving them as therapies. This review begins with the discovery of antibiotics, covers the modes of action of select antimicrobials, and ends with a literature review of the newest potential alternative approaches to overcoming the drug resistance phenomenon.

Bacteriophage as an Alternative to Antibiotics Promotes Growth Performance by Regulating Intestinal Inflammation, Intestinal Barrier Function and Gut Microbiota in Weaned Piglets

This study aimed to investigate the effects of dietary bacteriophage supplementation on growth performance, intestinal morphology, barrier function, and intestinal microbiota of weaned piglets fed antibiotic-free diet. A total of 120 weaned piglets were allotted to four dietary treatments with five pens/treatment and six piglets/pen in a 21-d feeding trial. The control diet was supplemented with 25 mg/kg quinocetone and 11.25 mg/kg aureomycin in the basal diet, while the three treatment diets were supplemented with 200, 400, or 600 mg/kg bacteriophage in the basal diet, respectively. There was no difference for growth performance and all measured indices of serum and intestinal tissues between 200 mg/kg bacteriophage group and the control group with antibiotics (P > 0.05). More importantly, compared with the control diet, dietary 400 mg/kg bacteriophage inclusion increased average daily gain and average daily feed intake, and decreased feed/gain ratio and diarrhea incidence of weaned piglets (P < 0.05). Also, piglets fed 400 mg/kg bacteriophage had elevated villi height (VH) in jejunum and ileum, reduced crypt depth (CD) in jejunum and ileum, and elevated VH/CD ratio in duodenum, jejunum and ileum (P < 0.05). Compared to the control group, piglets fed 400 mg/kg bacteriophage had lower interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), and higher interleukin-10 (IL-10) concentration in serum, and higher secretory immunoglobulin A (sIgA), intestinal trefoil factor (ITF), and tumor growth factor-alpha (TGF-α) content in the ileal mucosa (P < 0.05). Besides, dietary addition with 400 mg/kg bacteriophage decreased the D-lactate concentration and diamine oxidase (DAO) activity in serum, and increased the relative mRNA expression of ZO-1, Claudin-1, Occludin, TLR2, TLR4, and TLR9, as well as the relative protein expression of Occludin in the jejunum (P < 0.05). However, the growth performance and all analyzed parameters in serum and intestinal tissues were not further improved when piglets fed 600 vs. 400 mg/kg bacteriophage (P > 0.05). MiSeq sequencing analysis showed that bacteriophage regulated the microbial composition in caecum digesta, as indicated by higher observed_species, Chao1, and ACE richness indices, as well as changes in the relative abundance of Firmicutes, Bacteroidetes, and Tenericutes (P < 0.05). Collectively, 400 mg/kg bacteriophage can be used as an antibiotics alternative for promoting the growth of weaned piglets. The underlying mechanism is associated with a positive effect of bacteriophage on intestinal inflammation, intestinal barrier function and gut microbiota in weaned piglets.

Anti-Salmonella Potential of New Lactobacillus Strains with the Application in the Poultry Industry

Probiotics are considered an alternative to antibiotics in the prevention and treatment of Salmonella diseases in poultry. However, to use probiotics as proposed above, it is necessary to evaluate their properties in detail and to select the most effective bacterial strains in the application targeted. In this study, probiotic properties of new Lactobacillus sp. strains were investigated and their antimicrobial activity against 125 environmental strains of Salmonella sp. was determined using the agar slab method. Furthermore, their survival in the presence of bile salts and at low pH, antibiotics susceptibility, aggregation and coaggregation ability, adherence to polystyrene and Caco-2 cells, and cytotoxicity were investigated. Each strain tested showed antagonistic activity against at least 96% of the environmental Salmonella sp. strains and thus representing a highly epidemiologically differentiated collection of poultry isolates. In addition, the probiotic properties of new Lactobacillus strains are promising. Therefore, all strains examined showed a high potential for use in poultry against salmonellosis.

Probiotics are considered an alternative to antibiotics in the prevention and treatment of Salmonella diseases in poultry. However, to use probiotics as proposed above, it is necessary to evaluate their properties in detail and to select the most effective bacterial strains in the application targeted. In this study, probiotic properties of new Lactobacillus sp. strains were investigated and their antimicrobial activity against 125 environmental strains of Salmonella sp. was determined using the agar slab method. Furthermore, their survival in the presence of bile salts and at low pH, antibiotics susceptibility, aggregation and coaggregation ability, adherence to polystyrene and Caco-2 cells, and cytotoxicity were investigated. Each strain tested showed antagonistic activity against at least 96% of the environmental Salmonella sp. strains and thus representing a highly epidemiologically differentiated collection of poultry isolates. In addition, the probiotic properties of new Lactobacillus strains are promising. Therefore, all strains examined showed a high potential for use in poultry against salmonellosis.

Efficacy of experimental phage therapies in livestock

Bacteriophages are the most abundant form of life on earth and are present everywhere. The total number of bacteriophages has been estimated to be 1032 virions. The main division of bacteriophages is based on the type of nucleic acid (DNA or RNA) and on the structure of the capsid. Due to the significant increase in the number of multi-drug-resistant bacteria, bacteriophages could be a useful tool as an alternative to antibiotics in experimental therapies to prevent and to control bacterial infections in people and animals. The aim of this review was to discuss the history of phage therapy as a replacement for antibiotics, in response to EU regulations prohibiting the use of antibiotics in livestock, and to present current examples and results of experimental phage treatments in comparison to antibiotics. The use of bacteriophages to control human infections has had a high success rate, especially in mixed infections caused mainly by Staphylococcus, Pseudomonas, Enterobacter, and Enterococcus. Bacteriophages have also proven to be an effective tool in experimental treatments for combating diseases in livestock.

Veterinary use of bacteriophage therapy in intensively-reared livestock

Zoonoses are infectious diseases transmitted directly or indirectly between animals and humans. Several important zoonotic pathogens colonize farm animals asymptomatically, which may lead to contamination of the food chain and public health hazards. Moreover, routine sampling of carcasses at retail by government authorities over the past 20 years suggests the prevalence of antibiotic resistance in foodborne pathogens has increased. If this continues, antibiotics may be ineffective against such pathogens in the future and alternative approaches, such as phage therapy, may be necessary. Intensive livestock farming is the only realistic way of meeting the demand for meat from an increasing global population and growth in middle class consumers in developing countries, particularly in Asia. This review elaborates on the use of phages to control zoonotic pathogens in intensively-reared livestock (poultry and pigs).

Bacteriophages in Food Applications: From Foe to Friend

Bacteriophages (phages) have traditionally been considered troublesome in food fermentations, as they are an important cause of starter-culture failure and trigger significant financial losses. In addition, from an evolutionary perspective, phages have contributed to the pathogenicity of many bacteria through transduction of virulence genes. In contrast, phages have played an important positive role in molecular biology. Moreover, these agents are increasingly being recognized as a potential solution to the detection and biocontrol of various undesirable bacteria, which cause either spoilage of food materials, decreased microbiological safety of foods, or infectious diseases in food animals and crops. The documented successful applications of phages and various phage-derived molecules are discussed in this review, as are many promising new uses that are currently under development.

Framing the Future with Bacteriophages in Agriculture

The ability of agriculture to continually provide food to a growing world population is of crucial importance. Bacterial diseases of plants and animals have continually reduced production since the advent of crop cultivation and animal husbandry practices. Antibiotics have been used extensively to mitigate these losses. The rise of antimicrobial resistant (AMR) bacteria, however, together with consumers’ calls for antibiotic-free products, presents problems that threaten sustainable agriculture. Bacteriophages (phages) are proposed as bacterial population control alternatives to antibiotics. Their unique properties make them highly promising but challenging antimicrobials. The use of phages in agriculture also presents a number of unique challenges. This mini-review summarizes recent development and perspectives of phages used as antimicrobial agents in plant and animal agriculture at the farm level. The main pathogens and their adjoining phage therapies are discussed.

Probiotic supplementation protects weaned pigs against enterotoxigenic Escherichia coli K88 challenge and improves performance similar to antibiotics

These studies evaluated the effects of probiotics (PB) as a potential substitute for antibiotics (AB) on diarrhea in relation to immune responses and intestinal health in weaned pigs challenged with enterotoxigenic (ETEC) K88 (Exp. 1) and the effects of PB on performance and nutrient digestibility in weaned pigs (Exp. 2). In Exp. 1, 24 weaned barrows (4.9 ± 0.4 kg initial BW) were randomly assigned to 1 of 4 treatments. The treatments consisted of pigs fed an unsupplemented corn-soybean meal basal diet and not challenged (NON-C) or challenged with ETEC K88 (CHA-C) on d 9 and pigs fed the same basal diet supplemented with AB (100 mg/kg zinc bacitracin, 50 mg/kg colistin sulfate, and 100 mg/kg olaquindox; CHA-AB) or 500 mg/kg PB ( and ; CHA-PB) and challenged with ETEC K88 on d 9. In Exp. 2, 108 weaned pigs (7.5 ± 0.9 kg initial BW) not challenged with ETEC K88 were randomly assigned to 1 of 3 treatments, including an AB-free basal diet (CON) and the basal diet with AB (ABD) or 500 mg/kg PB supplementation (PBD). In Exp. 1, after challenge, CHA-C decreased ( < 0.05) ADG and ADFI, whereas CHA-AB and CHA-PB revealed no significant change compared with NON-C. Compared with CHA-C, CHA-AB and CHA-PB improved ( < 0.05) ADG and ADFI and decreased ( < 0.05) the diarrhea incidence in pigs. Mucosal secretory Ig A contents in the jejunum and ileum were greater in CHA-C than in NON-C ( < 0.05) and lower than in CHA-PB ( < 0.05). The diet containing PB alleviated the increase in the endotoxin and diamine oxidase concentration and cecal count ( < 0.05) and the decrease in intestinal villus height, cecal count, and jejunal mucosal occludin protein abundance ( < 0.05). In Exp. 2, dietary supplementation with AB and PB had positive effects on ADG and feed efficiency ( < 0.05). Compared with CON, apparent digestibility of nutrients in PBD was improved ( < 0.05). Collectively, PB supplementation protected the pigs against ETEC K88 infection by enhancing immune responses and attenuating intestinal damage and improved the performance and nutrient digestibility of weaned pigs. Therefore, PB could be a potential effective alternative to AB for ameliorating diarrhea and improving performance in weaned pigs.

Phage Therapy Approaches to Reducing Pathogen Persistence and Transmission in Animal Production Environments: Opportunities and Challenges

The era of genomics has allowed for characterization of phages for use as antimicrobials to treat animal infections with a level of precision never before realized. As more research in phage therapy has been conducted, several advantages of phage therapy have been realized, including the ubiquitous nature, specificity, prevalence in the biosphere, and low inherent toxicity of phages, which makes them a safe and sustainable technology for control of animal diseases. These unique qualities of phages have led to several opportunities with respect to emerging trends in infectious disease treatment. However, the opportunities are tempered by several challenges to the successful implementation of phage therapy, such as the fact that an individual phage can only infect one or a few bacterial strains, meaning that large numbers of different phages will likely be needed to treat infections caused by multiple species of bacteria. In addition, phages are only effective if enough of them can reach the site of bacterial colonization, but clearance by the immune system upon introduction to the animal is a reality that must be overcome. Finally, bacterial resistance to the phages may develop, resulting in treatment failure. Even a successful phage infection and lysis of its host has consequences, because large amounts of endotoxin are released upon lysis of Gram-negative bacteria, which can lead to local and systemic complications. Overcoming these challenges will require careful design and development of phage cocktails, including comprehensive characterization of phage host range and assessment of immunological risks associated with phage treatment.

Productive performance of weanling piglets was improved by administration of a mixture of bacteriophages, targeted to control Coliforms and Clostridium spp. shedding in a challenging environment

This study was conducted to investigate the effects of bacteriophages in different environments on growth performance, digestibility, ileal and caecal microbiota, gut morphology and immunity of weanling pigs. Two hundred piglets were randomly assigned to four treatment groups with five replicate pens with 10 pigs per pen. A 2 × 2 factorial arrangement of treatments was used to investigate the response of weanling pigs to supplemental bacteriophages (0 and 1.0 g/kg of diet) in contaminated or hygienic environments. Bacteriophages supplementation did not affect average daily gain (ADG), average daily feed intake (ADFI) and gain:feed in phases I and III; however, there was a significant improvement in ADG and gain:feed in phase II. The supplementation of bacteriophages increased the overall gain:feed of pigs. The overall result showed a greater ADG and ADFI in hygienic room. There were reductions in population of both ileal (p < 0.05) and caecal (p < 0.01) Clostridium spp. and ileal coliforms (p < 0.01) with the inclusion of bacteriophages in the diet. Bacteriophages increased ileal Lactobacillus and caecal Bifidobacterium and tended to increase ileal Bifidobacterium (p = 0.08). Contaminated environment decreased ileal Lactobacillus and caecal Bifidobacterium and tended to increase ileal Clostridium (p = 0.08) and coliforms (p = 0.08). Total anaerobic bacteria was tended to decrease (p = 0.06) in contaminated environment. Jejunal villus height increased in pigs received bacteriophages, but they did not affect other morphological items. The interaction between bacteriophages and environment tended to be significant (p = 0.06) for ileal villus height and ileal villus height to crypt depth ratio. The overall faecal score was significantly greater in hygienic environment and bacteriophages groups. The present findings indicate that there is an interactive effect on feed efficiency between bacteriophages and contaminated environment. In addition, bacteriophages improve jejunum morphology, and intestinal microbiota of pigs.

Bacteriophage cocktail and multi-strain probiotics in the feed for weanling pigs: effects on intestine morphology and targeted intestinal coliforms and Clostridium

Two experiments were conducted to investigate the effects of dietary supplementation of bacteriophage cocktail, probiotics and a combination of these two supplements on performance and gut health of weanling pigs. In Experiment 1, 150 weaned piglets were randomly allotted to three treatments on the basis of BW. The dietary treatments included a basal diet supplemented with 0 (control), 1.0 and 1.5 g/kg bacteriophage cocktail. Pigs fed 1.0 and 1.5 g/kg bacteriophage product had greater (P<0.05) average daily gain (ADG), apparent total tract digestibility of dry matter from day 22 to 35, ileal Lactobacillus spp., villus height (duodenum and jejunum), and fewer coliforms (ileum) and Clostridium spp. (ileum). In Experiment 2, 200 weaned piglets were randomly allotted to four treatments. Dietary treatments included basal diet, basal diet supplemented with 3.0 g/kg fermented probiotic product (P), 1.0 g/kg bacteriophage cocktail (B) and combination of 1.0 g/kg bacteriophage cocktail and 3.0 g/kg fermented probiotic product. Pigs fed bacteriophage cocktail diets had greater (P<0.05) overall ADG, gain to feed ratio (G : F), fecal score from day 8 to day 21, and pigs fed bacteriophage cocktail diets had fewer coliforms (ileum) Clostridium spp. (ileum and cecum). Probiotics significantly increased G : F, colonization of Lactobacillus spp. in ileum. At day 35, bacteriophage treatment group showed greater (P<0.05) villus height of the duodenum, but a deeper crypt in duodenum. The present results indicate that the bacteriophage cocktail had a potential to enhance the performance and gut health of weanling pigs, however their combination with probiotics did not show an interaction.

Bacteriophages as antimicrobial agents against major pathogens in swine: a review

In recent years, the development of antibiotic resistant bacteria has become a global concern which has prompted research into the development of alternative disease control strategies for the swine industry. Bacteriophages (viruses that infect bacteria) offer the prospect of a sustainable alternative approach against bacterial pathogens with the flexibility of being applied therapeutically or for biological control purposes. This paper reviews the use of phages as an antimicrobial strategy for controlling critical pathogens including Salmonella and Escherichia coli with an emphasis on the application of phages for improving performance and nutrient digestibility in swine operations as well as in controlling zoonotic human diseases by reducing the bacterial load spread from pork products to humans through the meat.