Comparative Effects of Antibiotic and Antimicrobial Peptide on Growth Performance, Gut Morphology, Intestinal Lesion Score, Ileal Microbial Counts, and Immune Status in Broilers Challenged with Necrotic Enteritis

This experiment aimed to compare the efficacy of an antimicrobial peptide (AMP) with a conventional antibiotic growth promoter (AGP) during necrotic enteritis (NE) challenge in broilers. In total, 720 1-day-old exclusively male broiler chicks (Ross-308) were allocated to five treatments, each with six replicates of 24 birds (n = 144/treatment), for 35 days. The treatments were as follows: (1) uninfected control (UC) with basal diet, (2) infected control (IC) with C. perfringens challenge and basal diet, (3) CP-AGP with C. perfringens challenge and 200 g/ton enramycin throughout trial, (4) CP-AMP1 with C. perfringens challenge and 200 g/ton AMP in all phases, and (5) CP-AMP2 with C. perfringens challenge and 300 g/ton AMP throughout experiment. To induce NE, the birds were predisposed with 10 × coccidia vaccine (day 15) followed by oral gavage of C. perfringens type G (1 ml; 1 × 108 CFU/ml/bird) at days 19 and 20. The results showed that AMP supplemented at 300 g/ton of diet improved body weight gain and FCR in both non-challenge (days 1-14) and challenge phases (days 15-35) as compared to the infected control (P < 0.05). Moreover, it also enhanced the livability and production efficiency factor (P < 0.0001). AMP at 300 g/ton also reduced NE lesion scores, and coccidia oocyst shedding, and positively affected intestinal morphology, gut microbial balance, immune organ weights, and HI titers against Newcastle disease (P < 0.0001). These findings suggest that AMP at 300 g/ton of diet could effectively mitigate NE and may be used as a viable substitute for AGPs in broiler diets during the NE challenge.

Dietary apidaecin Api-PR19 addition enhances growth performance by regulating gut health and microbiota in broilers

OBJECTIVE

This study investigated the effects of Apidaecin Api-PR19 as feed additive on growth performance, intestinal health, and small intestinal microbiota of broilers.

METHODS

A total of 360 1-d-old Arbor Acres broilers were randomly assigned to 3 groups with 6 replicates including control group with basal diet (CON), antibiotic growth promotor group with basal plus 10 mg/kg colistin sulfate and 50 mg/kg roxarsone (AGP), and antibacterial peptide group with basal diet plus 330 mg/kg Apidaecin Api-PR19 (ABP). The trial lasted 35 d.

RESULTS

Results showed that dietary Api-PR19 addition increased (p<0.05) the average daily feed intake, average daily gain and decreased (p<0.05) feed conversion ratio (FCR) during 1 to 21 d compared with the CON group. The digestibility of dry matter and crude protein were higher in AGP and ABP groups (p<0.05) where greater trypsin activity was detected in duodenum (p<0.05). The ratio of villus height to crypt depth (V/C) in duodenum and jejunum was increased at 35 d when broilers were given diets with ABP or AGP (p<0.05). Besides, ABP treatments up-regulated (p<0.05) the mRNA expression of EAAT3, GLUT2, ZO-1, and Claudin-1 in duodenum of broilers at 35 d of age. The results of immunohistochemistry showed that ABP treatment significantly increased (p<0.05) duodenal secretory immunoglobulin A (sIgA) content. In addition, 16S rRNA gene sequencing revealed that there were differences in the intestinal microbiota diversity and composition among three groups. Notably, the linear discriminant analysis effect size showed that p_Firmicutes, g_Enterococcus, g_Carnobacterium, g_Kitasatospora, and g_Acidaminococcus were dominant in ABP group. Redundancy analysis showed that these changes in gut microbiota in ABP group had correlation with growth performance, intestinal morphology, and content of sIgA.

CONCLUSION

In general, these results indicated that dietary 330 mg/kg Apidaecin Api-PR19 supplementation promoted growth performance of broilers by improving intestinal development, nutrients absorption, immune function and modulating intestinal microbiota.

Protective effects of rabbit sacculus-derived antimicrobial peptides on SPF chicken against infection with very virulent infectious bursal disease virus

Previous studies here have demonstrated that the rabbit sacculus rotundus-derived antimicrobial peptides (RSRP) could alter the intestinal mucosal immune responses in specific-pathogen-free (SPF) chickens, however, the protective effects of RSRP on chickens against infection remain questionable. In the present study, eighty SPF chickens were randomly divided into five groups and challenged with very virulent infectious bursal disease virus (vvIBDV) to determine the protective effects and its underlying mechanism of RSRP. Histopathology examination found that vvIBDV-infection caused severe damage in the bursa of Fabricius, especially the bursal lymphoid follicles underwent severe necrosis, depletion, hemorrhage, and edema. Unexpectedly, RSRP intervention significantly reduced the necrosis and depletion of lymphoid follicles in the vvIBDV-infected chickens. Moreover, RSRP treatment significantly decreased the expression of Bax (P < 0.01) as well as remarkably promoted the expression of Bcl-2 (P < 0.01), concomitantly alleviated the excessive apoptosis in the immune organs such as the bursa of Fabricius during vvIBDV infection. Notably, consistent with our previous reports that increased mast cell activation and degranulation in the bursa after vvIBDV infection, RSRP administration considerably reduced the mast cell density and the expression of tryptase, a marker for activated mast cells. Collectively, the present study indicates that rabbit sacculus rotundus-derived antimicrobial peptides could effectively protect the major immune organs including the bursa of Fabricius from the damage caused by vvIBDV infection, which provides the possibility and a promising perspective for the future application of antimicrobial peptides for poultry production.

Coated oregano essential oil and cinnamaldehyde compounds supplementation improves growth performance, enhances immune responses, and inhibits cecal Escherichia coli proliferation of broilers

Plant essential oils are unstable due to high volatility and easy oxidation, while microencapsulation provides a potentially effective strategy for increasing the stability of natural essential oils and preserving their function. This study examined the effects of feeding coated oregano essential oil and cinnamaldehyde (COEC) compounds on growth, immune organ development, intestinal morphology, mucosal immune function, and the cecal microbiota populations of broilers. Three hundred one-day-old male Arbor Acres broiler chicks were organized into 5 groups: 1) negative control fed basal diet alone (NC), 2) positive control receiving basal diet plus 50 mg/kg of chlortetracycline (CTC), 3) basal diet plus 150 mg/kg COEC (COEC150), 4) plus 300 mg/kg COEC (COEC300), and 5) plus 450 mg/kg COEC (COEC450). The supplement trial was continued for 42 d. The results showed that CTC, COEC300, and COEC450 treatments decreased the feed conversion ratio of broilers both in the starter and whole experiment phases, increased the height of jejunal villi at 21 d and the number of goblet cells and IgA-producing cells at 21 or 42 d compared with NC group (P < 0.05). Members of the COEC300 treatment group had a higher thymus weight index and jejunum length index than birds of NC or CTC groups at 21 d (P < 0.05). CTC and all COEC treatments decreased malondialdehyde content in jejunal mucosa at 42 d (P < 0.05). The population of Escherichia coli (E. coli) in the cecal digesta at 21 d was lower in the CTC, COEC300, and COEC450 treatment groups compared with the NC group (P < 0.05). In contrast to the CTC group, COEC supplementation dose-dependently accelerated body weight gain, improved jejunal morphology, decreased malondialdehyde content in jejunal mucosa, increased numbers of jejunal goblet cells and IgA-producing cells, and decreased the E. coli population in cecal digesta at 21 or 42 d (P < 0.05). Thus, we concluded that feeding broiler chickens with 300 or 450 mg/kg in antibiotic-free diets can improve growth performance, enhance immune responses, and inhibit the proliferation of cecal pathogenic bacteria.

Probiotics and the Potential of Genetic Modification as a Possible Treatment for Food Allergy

Food allergy is a common condition that affects millions of people worldwide. It is caused by an abnormal immune response to harmless food antigens, which is influenced by genetics and environmental factors. Modulating the gut microbiota and immune system with probiotics or genetically modified probiotics confers health benefits to the host and offers a novel strategy for preventing and treating food allergy. This systematic review aims to summarize the current proof of the role of probiotics in food allergy and propose a promising future research direction of using probiotics as a possible strategy of treatment for food allergy.

Guanidinoacetic acid supplementation improves intestinal morphology, mucosal barrier function of broilers subjected to chronic heat stress

The current study is designed to investigate dietary guanidinoacetic acid (GAA) supplementation on the growth performance, intestinal histomorphology, and jejunum mucosal barrier function of broilers that are subjected to chronic heat stress (HS). A total of 192 male broilers (28-d old) were randomly allocated to four groups. A chronic HS model (at a temperature of 32 °C and 50%-60% relative humidity for 24 h daily) was applied in the experiment. Normal control (NC, ad libitum feeding, 22 °C), HS group (HS, ad libitum feeding, 32 °C), pair-fed group (PF, received food equivalent to that consumed by the HS group on the previous day, 22 °C), guanidinoacetic acid group (HG, ad libitum feeding, supplementing the basal diet with 0.6 g/kg GAA, 32 °C). The experiment lasted from 28 to 35 and 28 to 42 d of age of broilers. Our results showed that broilers subjected to HS had lower average daily feed intake and average daily gain (P < 0.05), higher feed-to-gain ratio and relative length of the small intestine (P < 0.05), as well as lower relative weight and weight per unit length of the small intestine (P < 0.05). HS damaged the small intestinal histomorphology by decreasing the small intestinal VH and the VH/CD (P < 0.05). Compared with the HS group, supplementation with 0.6 g/kg GAA increased jejunal VH and VH/CD (P < 0.05), but decreased relative weight and relative length of the small intestine (P < 0.05). Moreover, in comparison with NC, HS elevated intestinal permeability (D-Lactic acid concentration and diamine oxidase activity) and mRNA expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α (P < 0.05), reduced jejunal mucus thickness, number of goblet cells, IgA + cell density, and mucin2 mRNA expression level of broilers (P < 0.05). Compared with the HS group, dietary GAA elevated jejunal mucus thickness, goblet cell number and IgA+ cell density (P < 0.05), and up-regulated jejunal mRNA expression of interleukin-1β and tumor necrosis factor-α (P < 0.05). In conclusion, HS impaired growth performance, and the intestinal mucosal barrier function of broilers. Dietary supplementation with 0.6 g/kg GAA alleviated HS-induced histomorphology changes of small intestine and jejunal mucosal barrier dysfunction.

Effects of melittin on laying performance and intestinal barrier function of quails

To study the effects of melittin on egg-laying performance and intestinal barrier of quails, 240 quails (aged 70 d) were randomly divided into 4 groups with 6 replicates (10 quails per replicate). They were fed with basal diet (group B), basal diet + 0.08 g/kg melittin (group BA1), basal diet + 0.12 g/kg melittin (group BA2) and basal diet + 0.16 g/kg melittin (group BA3). The experiment lasted for 21 days. The eggs were collected every day. At the end of the experiment, duodenal, jejunal, and ileal tissues were collected, and the cecal contents were sampled. Intestinal antioxidant index, barrier function, and intestinal flora were analyzed. The results showed that the addition of melittin significantly increased the laying rate and average egg weight. Addition of melittin significantly increased the antioxidant function, mechanical barrier, immune barrier, and the villus height to crypt depth ratio of small intestine. Addition of melittin had no significant effect on the α and β diversity of cecal flora, but significantly increased the abundance of Bacteroidales at family level and genus level. Bioinformatics analysis of cecal content showed significant increase in COG functional category of cytoskeleton, and significant decrease in RNA processing and modification in group BA2. KEGG functional analysis showed significant decrease in steroid biosynthesis, caffeine metabolism, and cytochrome P450 pathways in group BA2. In conclusion, addition of 0.12 g/kg melittin to feed improved the laying performance and the intestinal antioxidant capacity and barrier function of quails but had no significant effect on the composition and structure of cecal microbial community. This study provides experimental data and theoretical basis for the application of melittin as a new quail feed additive.

Effects of bioactive peptides derived from feather keratin on plasma cholesterol level, lipid oxidation of meat, and performance of broiler chicks

In this research, the effect of mixed feather bioactive peptides (MFBPs) added in water, on intestinal health, meat quality, and plasma cholesterol level of broiler chickens, was evaluated. A total of 80 day-old male broiler chicks (Ross 308) were randomly divided into two treatments with four replication pens. The dietary treatments were the drinking water with no additives (control) and drinking water containing 50 mg/L of MFBPs. Live weight and feed intake were measured at the end of starter (1-10 days), grower (11-24 days), and finisher (25-36 days) periods by calculating the average daily gain and feed conversion ratio. The results indicate that body weight gain was greater (P < 0.05) in birds that received MFBPs in the final period. At 24 days of age, the villus height and muscle layer thickness in different parts of the intestine were higher in birds that received bioactive peptides but epithelial thickness was lower than that in control birds (P < 0.05). In addition, the administration of MFBPs decreased (P < 0.01) serum total cholesterol, triglyceride, and low-density lipoprotein in broilers. Supplementation with MFBPs significantly reduced (P < 0.01) the malondialdehyde (MDA) amount in the thigh muscle. In conclusion, using the MFBPs in the diet of broilers could improve meat quality, cholesterol concentration in serum, and gut health.

Enantioselective characteristics, bioaccumulation and toxicological effects of chlordane-related compounds in laying hens

Chlordane-related compounds are ubiquitously detected in the environment and can transfer and accumulate to animals through food chain to cause adverse effects. In this study, the dynamic distribution and the enantiomeric profile of chlordane-related compounds in laying hens over time were investigated. The effect of these compounds on immune-associated cells in the intestinal tract and histopathology in some tissues were also evaluated after long-term exposure. The chlordane-related compounds preferentially accumulated in fat, followed by the intestines, ovum, and egg yolk during long-term exposure. The metabolites heptachlor epoxide and oxychlordane were mainly formed in the liver of hens by epoxidation or hydroxylation. The high accumulation ratios of trans-nonachlor and MC5 were found in ovum and egg yolk after long-term exposure, implying a greater risk to the hens' offspring. Chlordane-related compounds may cause abnormal lipometabolism and glycometabolism in liver of hens. Additionally, (-)-Cis-chlordane was dominant in all tissues of laying hens and its dominance increased over time. Conversely, (+)-isomer of metabolite oxychlordane was overwhelmingly dominant during the experiment. These findings about enantioselectivity, metabolic processes and toxicological effects are crucial in understanding the exposure risk of chlordane-related compounds.

The combined impact of xylo-oligosaccharides and gamma-irradiated astragalus polysaccharides on the immune response, antioxidant capacity and intestinal microbiota composition of broilers

The present study investigated the individual and combined effects of xylo-oligosaccharides (XOS) and gamma-irradiated astragalus polysaccharides (IAPS) on the immune response, antioxidant capacity and intestinal microbiota composition of broiler chickens. A total of 240 newly hatched Ross 308 chicks were randomly allocated into 5 dietary treatments including the basal diet (control), or the basal diet supplemented with 50 mg/kg chlortetracycline (CTC), 100 mg/kg XOS (XOS), 600 mg/kg IAPS (IAPS), and 100 mg/kg XOS + 600 mg/kg IAPS (XOS + IAPS) respectively. The results showed that birds in the control group had lower the thymus index and serum lysozyme activity than those in the other 4 groups (P < 0.05). Moreover, there was an interaction between XOS and IAPS treatments on increasing the serum lysozyme activity (P < 0.05). Birds in the CTC and XOS + IAPS groups had lower serum malondialdehyde concentration and higher serum total antioxidant capacity activity and mucosal interleukin 2 mRNA expression of jejunum than those in the control group (P < 0.05). In addition, birds in the control groups had lower duodenal and jejunal IgA-producing cells number than these in other 4 groups (P < 0.05). As compared with the CTC group, dietary individual XOS or IAPS administration increased duodenal IgA-producing cells number (P < 0.05). Meanwhile, there was an interaction between XOS and IAPS treatments on increasing duodenal and jejunal IgA-Producing cells numbers (P < 0.05). Dietary CTC administration increased the proportion of Bacteroides, and decreased the proportion of Negativibacillus (P < 0.05). However, dietary XOS + IAPS administration increased Firmicutes to Bacteroidetes ratio, the proportion of Ruminococcaceae, as well as decreased the proportion of Barnesiella and Negativibacillus (P < 0.05). In conclusion, the XOS and IAPS combination could improve intestinal mucosal immunity and barrier function of broilers by enhancing cytokine gene expression, IgA-producing cell production and modulates cecal microbiota, and the combination effect of XOS and IAPS is better than that of individual effect of CTC, XOS, or IAPS in the current study.

Effects of Antimicrobial Peptide Microcin C7 on Growth Performance, Immune and Intestinal Barrier Functions, and Cecal Microbiota of Broilers

Microcin C7 is an antimicrobial peptide produced by Escherichia coli, composed of a heptapeptide with a modified adenosine monophosphate. This study was performed to evaluate the effects of Microcin C7 as a potential substrate to traditional antibiotics on growth performance, immune functions, intestinal barrier, and cecal microbiota of broilers. In the current study, 300 healthy Arbor Acres broiler chicks were randomly assigned to one of five treatments including a corn-soybean basal diet and basal diet supplemented with antibiotic or 2, 4, and 6 mg/kg Microcin C7. Results showed that Microcin C7 significantly decreased the F/G ratio of broilers; significantly increased the levels of serum cytokine IL-10, immunoglobulins IgG and IgM, and ileal sIgA secretion; significantly decreased the level of serum cytokine TNF-α. Microcin C7 significantly increased villus height and V/C ratio and significantly decreased crypt depth in small intestine of broilers. Microcin C7 significantly increased gene expression of tight junction protein Occludin and ZO-1 and significantly decreased gene expression of pro-inflammatory and chemokine TNF-α, IL-8, IFN-γ, Toll-like receptors TLR2 and TLR4, and downstream molecular MyD88 in the jejunum of broilers. Microcin C7 significantly increased the number of Lactobacillus and decreased the number of total bacteria and Escherichia coli in the cecum of broilers. Microcin C7 also significantly increased short-chain fatty acid (SCFA) and lactic acid levels in the ileum and cecum of broilers. In conclusion, diet supplemented with Microcin C7 significantly improved growth performance, strengthened immune functions, enhanced intestinal barrier, and regulated cecal microbiota of broilers. Therefore, the antimicrobial peptide Microcin C7 may have the potential to be an ideal alternative to antibiotic.

A study on fungal defensin against multidrug-resistant Clostridium perfringens and its treatment on infected poultry

In the present study, we aimed to investigate the antibacterial activity and mechanisms of plectasin-derived peptide NZ2114 in vitro and its therapeutic effects in vivo on broilers challenged with Clostridium perfringens. In vitro assay showed that NZ2114 had potent (minimal inhibitory concentration, 0.91 μM) and rapid antibacterial activity (99.9% reduction within 2 h), and the dual antibacterial mechanisms (including interfering with the cell membrane and intracellular DNA) against C. perfringens CVCC 2030. In vivo study, NZ2114 tended to increase linearly and quadratically the average daily gain as NZ2114 level increased and was the highest at 20 mg/L. NZ2114 at 10 ~ 40 mg/L dramatically reduced jejunal lesion score. Besides, the levels of IL-6, TNF-α, and IL-1β tended to downregulate linearly and quadratically as the NZ2114 level increased and were all the lowest at the dose of 20 mg/L. NZ2114 significantly upregulated those levels of IgA, IgG, IgM, and sIgA with a linear and quadratic dose effect, with the highest IgA, IgG, IgM, and sIgA at 20 mg/L. Finally, NZ2114 tended to linearly and quadratically increase the numerical value of crypt depth, with the lowest value at 40 mg/L. Lincomycin only dramatically reduced the jejunal lesion score and increased the numerical value of crypt depth. These results indicate that NZ2114 has the potential as a new alternative to antibiotics for the treatment of C. perfringens-induced necrotic enteritis infection.Key points• NZ2114 could kill C. perfringens by dual antibacterial mechanisms• Broiler necrotic enteritis model induced by C. perfringens was established• NZ2114 treatment could ameliorate C. perfringens-induced necrotic enteritis.

Effects of Dietary Supplementation of Recombinant Plectasin on Growth Performance, Intestinal Health and Innate Immunity Response in Broilers

The present study was conducted to evaluate the effects of dietary supplementation of recombinant plectasin (Ple) on the growth performance, intestinal health, and serum immune parameters in broilers. A total of 288 1-day-old male broilers (Arbor Acres) were randomly allotted to four dietary treatments including the basal diet (NC) and basal diet supplemented with 10 mg enramycin/kg (PC), 100 mg Ple/kg (LPle), and 200 mg Ple/kg (HPle) diets. The results indicated Ple increased (P < 0.01) average daily gain and decreased (P ≤ 0.02) feed to gain ratio of broilers. In addition, the supplementation of Ple in the diets increased (P ≤ 0.01) duodenal lipase (day 21) and trypsin (day 42) activities compared with the NC group. Similar as the supplementation of enramycin, Ple also increased villus height and decreased crypt depth in jejunum (day 21), and thus the villus height to crypt depth ratio (P < 0.01) was increased compared to the NC group on day 42. The serum immunoglobulin M (days 21 and 42), immunoglobulin G (day 42), complement 3 (day 21), and complement 4 (days 21 and 42) were significantly increased (P ≤ 0.02) due to the supplementation of Ple and enramycin, while the concentration of malondialdehyde in jejunum was decreased (P < 0.01) in PC, LPle, and HPle groups on day 21 compared with those in the NC group. Furthermore, Ple reduced (P < 0.01) Escherichia coli and total aerobic bacteria population in ileum and cecum of birds on days 21 and 42. These results indicate that the recombinant plectasin has beneficial effects on growth performance, intestinal health, and innate immunity in broilers.

HPMCP-Coated Microcapsules Containing the Ctx(Ile21)-Ha Antimicrobial Peptide Reduce the Mortality Rate Caused by Resistant Salmonella Enteritidis in Laying Hens

The constant use of synthetic antibiotics as growth promoters can cause bacterial resistance in chicks. Consequently, the use of these drugs has been restricted in different countries. In recent years, antimicrobial peptides have gained relevance due to their minimal capacity for bacterial resistance and does not generate toxic residues that harm the environment and human health. In this study, a Ctx(Ile21)-Ha antimicrobial peptide was employed, due to its previously reported great antimicrobial potential, to evaluate its application effects in laying chicks challenged with Salmonella Enteritidis, resistant to nalidixic acid and spectinomycin. For this, Ctx(Ile21)-Ha was synthesized, microencapsulated and coated with hypromellose phthalate (HPMCP) to be released in the intestine. Two different doses (20 and 40 mg of Ctx(Ile21)-Ha per kg of isoproteic and isoenergetic poultry feed) were included in the chick's food and administered for 28 days. Antimicrobial activity, effect and response as treatment were evaluated. Statistical results were analyzed in detail and indicate that the formulated Ctx(Ile21)-Ha peptide had a positive and significant effect in relation to the reduction of chick mortality in the first days of life. However, there was moderate evidence (p = 0.07), not considered statistically significant, in the differences in laying chick weight between the control and microencapsulation treatment groups as a function of time. Therefore, the microencapsulated Ctx(Ile21)-Ha antimicrobial peptide can be an interesting and promising option in the substitution of conventional antibiotics.

Antimicrobial peptides as an alternative to relieve antimicrobial growth promoters in poultry

1. This review describes different classes of antimicrobial peptides (AMP) found in the gastrointestinal (GI) tract of avian species, and their antimicrobial and immunomodulatory activities. The potential benefits of synthetic AMP in poultry production are examined, in the context of the use of AMP as alternatives to antimicrobial growth promoters (AGP).2. Since the mid-1950s, antibiotic growth promoters (AGP) have been used in feed at low prophylactic doses to modulate the homoeostasis of intestinal microbiota, decreasing the risk of intestinal dysbacteriosis and the growth of pathogens within the avian gut. Over the last three decades, AGP have faced major regulatory restrictions due to concerns of generating antimicrobial resistance (AMR). It is now well documented that the rate of infectious disease outbreaks is higher in flocks that are not fed prophylactic antibiotics, resulting in a compensatory increase in antimicrobial use for therapeutic purposes.3. Endogenous natural AMP production is associated with the presence of microbiota and their interaction with the intestinal epithelial and lamina propria lymphoid cells. Their antimicrobial activity shapes the beneficial microbiota population and controls intestinal pathogens such Clostridium and Salmonella spp., and stimulates the development and maturation of the local immune system.4. Similar to AGP, AMP can establish a well-balanced gut beneficial microbiota for adequate immune-competence, animal health and high growth performance parameters such as feed intake, daily weight, feed conversion and accumulated mortality.5. Antimicrobial proteins and peptides constitute an essential part of the innate immune system of all organisms and protect the host from invading pathogenic bacteria, viruses, fungi, and parasites by interacting with the negatively charged pathogen membranes.

Immunomodulatory responses in plectasin-supplemented broilers under tropical environmental conditions

The present study was aimed to determine the immunomodulatory effects of dietary supplementation of the antimicrobial peptide (AMP) plectasin on broiler chickens. The experiment involved 300-day-old Ross chicks reared in a conventional housing system and subjected to ambient temperature and relative humidity. The birds were randomly allocated to five treatment groups: the non-supplemented negative control group (T1), enramycin-supplemented group (T2), and groups supplemented with varying doses of plectasin at 150 ppm, 300 ppm, and 450 ppm (T3, T4, and T5, respectively) from day 1 to 35. The results indicated that plectasin supplementation increased jejunal and ileal goblet cell (GC) counts, serum interferon-gamma (IFN-γ) levels at neonatal age, and serum immunoglobulin Y (IgY) titer on days 7, 21, 28, and 35. These findings confirmed that plectasin induces positive immunomodulatory responses by specifically enhancing gut mucosal barriers, early innate immunity, and humoral immune response. Specifically, supplementation at 150 ppm may be considered as the optimal dose for inclusion in broiler chicken feeds.

Combined effects of xylo-oligosaccharides and coated sodium butyrate on growth performance, immune function, and intestinal physical barrier function of broilers

This study was conducted to investigate the effects of dietary supplementation xylo-oligosaccharides (XOS), coated sodium butyrate (CSB), and their combination on growth performance, immune parameters, and intestinal barrier of broilers. A total of 192 1-day-old chicks were assigned to a 2 × 2 factorial design including two dietary additives (0 and 150 mg/kg XOS and 0 and 400 mg/kg CSB). This trial lasted for 42 days. CSB supplementation increased the thymus and bursa index, blood myeloperoxidase (MPO) activity, and IgG and IgM concentrations, whereas adding XOS only improved IgM concentration (p < .05). A significant interaction was observed for MPO activity. Furthermore, broilers fed CSB and their interaction exhibited increased ileal villus height/crypt depth (VH/CD) and goblet cells numbers in the ileum, as well as decreased ileal CD (p < .05). Broilers fed XOS and CSB individually showed higher ileal VH, the number of goblet cells in the duodenum and jejunum (p < .05). Moreover, XOS and CSB individual supplementation upregulated the expression of claudin3 in the ileum (p < .05). Simultaneously, a significant interaction was found for the ileal expression of claudin3. Overall, XOS and CSB supplementation could improve the development of immune organs, the small intestine morphology, and the intestinal physical barrier of broilers. Although no clear synergy of XOS and CSB was detected, the combination had positively affect broilers intestinal barrier and immune parameters.

The combined impact of xylo-oligosaccharides and gamma-irradiated Astragalus polysaccharides on growth performance and intestinal mucosal barrier function of broilers

This study was conducted to investigate the individual and combined effects of xylo-oligosaccharides (XOS) and gamma-irradiated Astragalus polysaccharides (IAPS) on the growth performance and intestinal mucosal barrier function of broiler chickens. A total of 240 1-day-old Ross-308 chicks were allocated into 5 groups for 21 d: control group (basal diet), antibiotic growth promoter (AGP) group (basal diet supplemented with 50 mg/kg chlortetracycline), XOS group (basal diet supplemented with 100 mg/kg XOS), IAPS group (basal diet supplemented with 600 mg/kg IAPS), and XOS + IAPS group (basal diet supplemented with 100 mg/kg XOS and 600 mg/kg IAPS). The results showed that birds in the XOS + IAPS group showed higher ADG and lower feed-to-gain ratio than those in the control group (P < 0.05). The XOS, IAPS, and XOS + IASP treatments significantly increased villus height (VH) of all intestine segments, jejunal goblet cell numbers, and VH–to–crypt depth ratio (VH/CD) of broilers than those of the control group (P < 0.05). Birds in the XOS + IAPS group had higher jejunal VH/CD ratio and goblet cell numbers than those from the XOS or IAPS groups (P < 0.05). In addition, there was a synergy effect between XOS and IAPS on increasing duodenal goblet cell numbers and improving ileal morphology (higher VH and VH/CD ratio) (P < 0.05). The XOS, IAPS and XOS + IAPS treatments increased the mRNA expression of zonula occludens-1 and occludin of the jejunum as compared with the control group (P < 0.05). Simultaneously, birds in the XOS + IAPS group showed lower plasma D-lactic acid concentration and higher mRNA expression of claudin-1, claudin-3, and occludin in the jejunum than those in the control or IAPS groups (P < 0.05). Moreover, there was no significant difference in growth performance, intestinal morphology, and intestinal barrier function of broilers between the AGP and XOS + IAPS groups. In conclusion, the combination of XOS and IAPS had a better potential as chlortetracycline substitute for improving the growth performance, intestinal morphology, and intestinal barrier function of broilers.

Effects of Antimicrobial peptides on egg production, egg quality and caecal microbiota of hens during the late laying period

This study was conducted to determine the effects of diet supplementation of laying hens with antimicrobial peptides (AMP) on egg production, egg quality and caecal microbiota. A total of 360 Hy-Line Brown laying hens (72 weeks old) were divided into three groups with four replicates of 30 birds each. The laying hens were fed with the basal diet (Control), the basal diet + 50 mg/kg AMP (group 1) and the basal diet + 100 mg/kg AMP (group 2). The experiment lasted for 45 d. Eggs were collected daily and caecal samples were collected at the end of the experiment. The results showed that AMP supplementation caused a significantly increased laying rate and decreased feed/egg ratio (p ＜ .05). Meanwhile, a distinctive difference in cecal microbiota was observed between AMP and control groups and the average values of microbial diversity and richness were lower in the AMP group than in the control group. At the phylum level, the relative abundance of Verrucomicrobia and Cyanobacteria were lower in the AMP group than in the control group. In conclusion, the results indicated that dietary supplementation with AMP can improve egg production and affect the cecal microbial community membership and structure of hens during late laying period.

Protective effects of γ-irradiated Astragalus polysaccharides on intestinal development and mucosal immune function of immunosuppressed broilers

This study was aimed to assess the protective effects of γ-irradiated Astragalus polysaccharides (IAPS) on the development of small intestine and intestinal mucosal immunity of immunosuppressed broilers induced by cyclophosphamide (CPM). A total of 384 one-day-old broiler chicks with similar initial weight were randomly assigned into 6 groups: non-treated group (control), and CPM-treated groups fed either a basal diet or the diets containing 900 mg/kg APS, or 900, 600, 300 mg/kg IAPS, respectively. On days 16, 18, and 20, all broilers except for control group were intramuscularly injected with 0.5 mL CPM (40 mg/kg of BW). Broilers in the control group were intramuscularly injected with 0.5 mL sterilized saline (0.75%, wt/vol). This trial was lasted for 21 d. The results revealed that both APS and IAPS treatment elevated the duodenal IgA-producing cells number and the jejunal mRNA expression of interleukin-2 (IL-2), interleukin-10 (IL-10), and interferon γ of CPM-injected broilers (P < 0.05). The decreased jejunal villus height (VH), the ratio of VH to crypt depth (V/C), as well as the intestinal intraepithelial lymphocytes (IELs) and goblet cells number in CPM-injected broilers were elevated by dietary supplementation with 900 mg/kg APS or 900, 600 mg/kg IAPS (P < 0.05). The CPM-induced decrease in jejunum index, the duodenal VH and the jejunal IgA-producing cells number were only improved in the 900 mg/kg IAPS group (P < 0.05). Furthermore, the number of IELs and IgA-producing cells in duodenum, VH, V/C, the number of goblet cells, and mRNA expression of IL-2 and IL-10 in jejunum were higher in the 900 mg/kg IAPS group than those in the 900 mg/kg APS group (P < 0.05). In summary, IAPS possessed stronger immunomodulatory effect than APS at the same supplementation level. Therefore, gamma irradiation can be used as an alternative treatment to enhance the immunomodulatory activity of APS.

Gut barrier function: Effects of (antibiotic) growth promoters on key barrier components and associations with growth performance

The gut barrier, comprising the microbiota and their products, mucus layers, host-derived antimicrobial compounds [e.g., host defense peptides (HDP), IgA], epithelium, and underlying immune tissues, performs the essential function of preventing the passage of harmful microorganisms and substances into the body, while enabling the acquisition of dietary nutrients. Antibiotic growth promoters (AGP) are widely accepted as the "gold standard" of performance-enhancing feed additives, which had become integral and valuable components of modern, efficient animal production, but are now being phased out in many parts of the world. This review, therefore, examines the reported effects of AGP on the key components of gut barrier function, particularly where corresponding (positive) growth performance data were provided to indicate that any changes were beneficial, and some important trends do emerge. Certain bacterial families (e.g., Lachnospiraceae), genera (e.g., Faecalibacterium, Propionibacterium, and Ruminococcus), or species (e.g., F. prausnitzii, B. fragilis, and some Lactobacillus spp.) have been reported to increase with AGP use, are associated with improved growth performance, and show benefit across species, which may be related to their production of short-chain fatty acids (SCFA). Various studies have investigated the effects of AGP on mucus-related parameters (e.g., goblet cell size, density, and mucin mRNA expression) but these do not always seem to correlate well with the actual physical characteristics of the mucus layer(s). Surprisingly, there are little data relating to HDP or IgA, even though they have recognized benefits. There are clear AGP benefits on epithelial structure and function (e.g., nutrient digestibility), and these may (currently) provide the most reliable indicators of the efficacy of growth promoters. Data investigating effects on gut immune parameters (e.g., cell populations, cytokines, and chemokines), with corresponding growth performance, are limited and require further detailed interrogation. This review highlights both important observations related to the effects of AGP on key gut barrier components, with associated growth performance, and areas that require further investigation, thus providing an informative basis for assessing the potential of AGP alternatives.

Global restriction of using antibiotic growth promoters and alternative strategies in poultry production

A growing global concern of antibiotic use in poultry diets due to its potential adverse effects on birds and human health, food safety and the environment has led to a complete ban or restricted use in some countries, and, at the same time, expanding options for the use of alternative feed additives. Multiple, rather than a single additive may replace antibiotic growth promoters (AGPs) in poultry. Blending of feeding additives and hygienic farm management, vaccination and biosecurity may help achieve good intestinal health, stabilise enteric ecosystems and result in sustainable and cost effective production performance of birds. Moreover, controlling unsolicited ingredients at the production level must have the support of different markets responsible for the supply of safe and quality poultry products for consumers. This requires the further increase and diversification of value added poultry products and the expansion of their markets through strategic planning and gradual limitation of live bird markets. More research is warranted in order to explore suitable, reliable and cost effective alternatives to AGPs for commercial use, and strategic poultry value chain development.

Expression of a recombinant hybrid antimicrobial peptide magainin II-cecropin B in the mycelium of the medicinal fungus Cordyceps militaris and its validation in mice

Background

Antibiotic residues can cause antibiotic resistance in livestock and their food safety-related issues have increased the consumer demand for products lacking these residues. Hence, developing safe and effective antibiotic alternatives is important to the animal feed industry. With their strong antibacterial actions, antimicrobial peptides have potential as antibiotic alternatives.

Results

We investigated the antibacterial and immunomodulatory activities and the mechanisms of action of an antimicrobial peptide. The hybrid antimicrobial peptide magainin II-cecropin B (Mag II-CB) gene was transformed into the medicinal Cordyceps militaris fungus. Recombinant Mag II-CB exhibited broad-spectrum antibacterial activity in vitro and its antibacterial and immunomodulatory functions were evaluated in BALB/c mice infected with Escherichia coli (ATCC 25922). Histologically, Mag II-CB ameliorated E. coli-related intestinal damage and maintained the integrity of the intestinal mucosal barrier by up-regulating tight junction proteins (zonula occludens-1, claudin-1 and occludin). The intestinal microbial flora was positively modulated in the Mag II-CB-treated mice infected with E. coli. Mag II-CB treatment also supported immune functioning in the mice by regulating their plasma immunoglobulin and ileum secreted immunoglobulin A levels, by attenuating their pro-inflammatory cytokine levels, and by elevating their anti-inflammatory cytokines levels. Moreover, directly feeding the infected mice with the C. militaris mycelium producing Mag II-CB further proofed the antibacterial and immunomodulatory functions of recombinant hybrid antimicrobial peptide.

Conclusion

Our findings suggest that both purified recombinant AMPs and C. militaris mycelium producing AMPs display antibacterial and immunomodulatory activities in mice. And C. militaris producing AMPs has the potential to become a substitute to antibiotics as a feed additive for livestock in future.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-0865-3) contains supplementary material, which is available to authorized users.

Alternatives to antibiotics for maximizing growth performance and feed efficiency in poultry: a review

With the increase in regulations regarding the use of antibiotic growth promoters and the rise in consumer demand for poultry products from ‘Raised Without Antibiotics’ or ‘No Antibiotics Ever’ flocks, the quest for alternative products or approaches has intensified in recent years. A great deal of research has focused on the development of antibiotic alternatives to maintain or improve poultry health and performance. This review describes the potential for the various alternatives available to increase animal productivity and help poultry perform to their genetic potential under existing commercial conditions. The classes of alternatives described include probiotics, prebiotics, synbiotics, organic acids, enzymes, phytogenics, antimicrobial peptides, hyperimmune egg antibodies, bacteriophages, clay, and metals. A brief description of the mechanism of action, efficacy, and advantages and disadvantages of their uses are also presented. Though the beneficial effects of many of the alternatives developed have been well demonstrated, the general consensus is that these products lack consistency and the results vary greatly from farm to farm. Furthermore, their mode of action needs to be better defined. Optimal combinations of various alternatives coupled with good management and husbandry practices will be the key to maximize performance and maintain animal productivity, while we move forward with the ultimate goal of reducing antibiotic use in the animal industry.

Antimicrobial Peptides as Potential Alternatives to Antibiotics in Food Animal Industry

Over the last decade, the rapid emergence of multidrug-resistant pathogens has become a global concern, which has prompted the search for alternative antibacterial agents for use in food animals. Antimicrobial peptides (AMPs), produced by bacteria, insects, amphibians and mammals, as well as by chemical synthesis, are possible candidates for the design of new antimicrobial agents because of their natural antimicrobial properties and a low propensity for development of resistance by microorganisms. This manuscript reviews the current knowledge of the basic biology of AMPs and their applications in non-ruminant nutrition. Antimicrobial peptides not only have broad-spectrum activity against bacteria, fungi, and viruses but also have the ability to bypass the common resistance mechanisms that are placing standard antibiotics in jeopardy. In addition, AMPs have beneficial effects on growth performance, nutrient digestibility, intestinal morphology and gut microbiota in pigs and broilers. Therefore, AMPs have good potential as suitable alternatives to conventional antibiotics used in swine and poultry industries.

Fish oil enhances intestinal barrier function and inhibits corticotropin-releasing hormone/corticotropin-releasing hormone receptor 1 signalling pathway in weaned pigs after lipopolysaccharide challenge

Stress induces injury in intestinal barrier function in piglets. Long-chain n-3 PUFA have been shown to exhibit potential immunomodulatory and barrier protective effects in animal models and clinical trials. In addition, corticotropin-releasing hormone (CRH)/CRH receptor (CRHR) signalling pathways play an important role in stress-induced alterations of intestinal barrier function. We hypothesised that fish oil could affect intestinal barrier function and CRH/CRHR signalling pathways. In total, thirty-two weaned pigs were allocated to one of four treatments. The experiment consisted of a 2×2 factorial design, and the main factors included immunological challenge (saline or lipopolysaccharide (LPS)) and diet (5 % maize oil or 5 % fish oil). On d 19 of the trial, piglets were treated with saline or LPS. At 4 h after injection, all pigs were killed, and the mesenteric lymph nodes (MLN), liver, spleen and intestinal samples were collected. Fish oil decreased bacterial translocation incidence and the number of translocated micro-organisms in the MLN. Fish oil increased intestinal claudin-1 protein relative concentration and villus height, as well as improved the intestinal morphology. In addition, fish oil supplementation increased intestinal intraepithelial lymphocyte number and prevented elevations in intestinal mast cell and neutrophil numbers induced by LPS challenge. Moreover, fish oil tended to decrease the mRNA expression of intestinal CRHR1, CRH and glucocorticoid receptors. These results suggest that fish oil supplementation improves intestinal barrier function and inhibits CRH/CRHR1 signalling pathway and mast cell tissue density.

Detection of intestinal intraepithelial lymphocytes, goblet cells and secretory IgA in the intestinal mucosa during Newcastle disease virus infection

Newcastle disease, which is caused by Newcastle disease virus (NDV), is a highly contagious viral disease of poultry and other bird species. The mucosa is the first line of defence to invading pathogens, including NDV, and it has been confirmed that the mucosa can contribute to host protection. This study was conducted to evaluate the intestinal mucosal immunology in NDV infection. Forty specific-pathogen-free chickens were divided into two groups, 20 birds in each group. Group 1 was inoculated with NDV by the intravenous route. Group 2 was used as the control group and was given sterile phosphate-buffered saline by the same route. At 24, 48, 72, and 96 h post infection (h.p.i.), five chickens from each treatment were killed. Samples of the duodenum, jejunum, and ileum were collected to quantify intestinal intraepithelial lymphocytes (IEL), goblet cells and secretory IgA (sIgA) by cytochemistry and immunohistochemistry analysis. The results indicated that IEL were increased from 24 to 72 h.p.i. in the infected tissues, and were significantly higher than in the control group at 48 h.p.i. (P < 0.01). In contrast to IEL, goblet cell numbers were reduced dramatically from 24 to 96 h.p.i. in the infected birds (P < 0.01) Furthermore, the content of sIgA was significantly higher at 48 and 72 h.p.i. in the infected tissues (P < 0.01). sIgA positivity was observed in the epithelial lining of the intestinal mucosa. These data suggest that IEL, goblet cells, and sIgA were involved in the intestinal mucosal immunity against NDV infection.

β-1,3/1,6-Glucan alleviated intestinal mucosal barrier impairment of broiler chickens challenged with Salmonella enterica serovar Typhimurium

This study investigated the protective effect of β-1,3/1,6-glucan on gut morphology, intestinal epithelial tight junctions, and bacterial translocation of broiler chickens challenged with Salmonella enterica serovar Typhimurium. Ninety Salmonella-free Arbor Acre male broiler chickens were randomly divided into 3 groups: negative control group (NC), Salmonella Typhimurium-infected positive group (PC), and the Salmonella Typhimurium-infected group with dietary 100 mg/kg of β-1,3/1,6-glucan supplementation (T) to determine the effect of β-1,3/1,6-glucan on intestinal barrier function. Salmonella Typhimurium challenge alone significantly decreased villus height (P < 0.001), villus height/crypt depth ratio (P < 0.05), and the number of goblet cells (P < 0.001) in the jejunum at 14 d postinfection (dpi), but significantly increased the number of intestinal secretory IgA (sIgA)-expressing cells at 14 dpi (P < 0.01) and total sIgA levels in the jejunum at 7 (P < 0.05) and 14 dpi (P < 0.01) compared with the unchallenged birds (NC). Dietary β-1,3/1,6-glucan supplementation not only significantly increased villus height, villus height/crypt depth ratio, and the number of goblet cells (P < 0.01), but also increased the number of sIgA-expressing cells (P < 0.05) and sIgA content in the jejunum at 14 dpi (P < 0.01) in birds challenged with Salmonella Typhimurium in comparison with Salmonella Typhimurium challenge alone. β-1,3/1,6-Glucan addition had significant inhibitory effects (P < 0.05) on cecal Salmonella colonization levels and liver Salmonella invasion of the Salmonella Typhimurium-infected birds compared with the PC group. Intestinal tight junction proteins claudin-1, claudin-4, and occludin mRNA expression in the jejunum at 14 dpi was significantly decreased by Salmonella Typhimurium challenge alone (P < 0.01) compared with that of the NC group, whereas β-1,3/1,6-glucan supplementation significantly increased claudin-1 and occludin mRNA expression (P < 0.01) at 14 dpi in the jejunum of the Salmonella Typhimurium-infected birds in comparison with the PC group. Our results indicate that dietary β-1,3/1,6-glucan can alleviate intestinal mucosal barrier impairment in broiler chickens challenged with Salmonella Typhimurium.

The probiotic Bacillus licheniformis ameliorates heat stress-induced impairment of egg production, gut morphology, and intestinal mucosal immunity in laying hens

We investigated the effect of a 12-d exposure to 34°C plus dietary inclusion of the probiotic Bacillus licheniformis on the egg production, gut morphology, and intestinal mucosal immunity of laying hens. Ninety-six commercial hens (Hy-Line Brown) at the age of 60 wk were randomly allocated to 4 groups. After a period of laying rate adjustment (14 d), all the hens were subjected to 2 temperature treatments (12 d). Birds in 1 group were raised at 21°C and fed a basal diet, and birds in the other 3 groups were raised at 34°C and fed a basal diet supplemented with 0, 10(6), or 10(7) cfu of B. licheniformis per gram of feed, respectively. Rearing at 34°C depressed egg production and feed intake (P < 0.05). Compared with birds kept at 21°C, birds kept at 34°C had elevated serum levels of tumor necrosis factor-α (d 6), IL-1 (d 6 and 12), and corticosterone (d 6); decreased villus height (ileum: d 6; cecum: d 6 and 12) and ratio of villus height to crypt depth (ileum: d 6; cecum: d 6 and 12); fewer intraepithelial lymphocytes (ileum: d 6; cecum: d 6) and IgA-secreting cells (ileum: d 6; cecum: d 6 and 12); and more mast cells (ileum: d 6; cecum: d 6 and 12; P < 0.05). The number of goblet cells in the cecum increased at d 6 in heat-treated birds, and then deceased at d 12 (P < 0.05). Moreover, morphological examination showed injury to the villi of birds kept at 34°C. In general, inclusion of 10(7) cfu/g of B. licheniformis in the diet of heat-stressed hens was effective in overcoming the observed decline in egg production and feed intake, restoring the impaired villus structure, and sustaining a balanced mucosal immune response. Therefore, the probiotic B. licheniformis may be useful for ameliorating the adverse influence of heat on the egg production and gut health of laying hens.

Dose-response effects of an antimicrobial peptide, a cecropin hybrid, on growth performance, nutrient utilisation, bacterial counts in the digesta and intestinal morphology in broilers

The aim of the present study was to evaluate the feasibility of an antimicrobial peptide, cecropin A(1-11)-D(12-37)-Asn (CADN), as an alternative to antibiotic growth promoter (AGP) in poultry diets. A total of 1500 14-d-old indigenous male chickens (222 (sd 13) g) were randomly allocated to five groups with five replicate cages of sixty birds each, and fed ad libitum five grower diets and subsequently five finisher diets for 14 d each. The diets were made up by supplementing their basal diets with a CADN liquid sample (CADNL) at 0, 2, 4, 6 and 8 ml/kg, respectively. During the feeding period, a metabolic experiment was carried out to determine the apparent digestibility of diethyl ether extract, nitrogen retention and apparent metabolisable energy of the diet sample fed to each cage of chicks. At the end of the feeding experiment, one chick from each cage was killed for bacteriological, light microscopic and scanning electron microscopic examination of the intestinal villi. CADN had a negative linear, positive quadratic and negative linear effect on feed intake (F), weight gain (G) and feed:gain ratio (F:G), respectively, for the growers; it had a quadratic effect on F, G or F:G for the finishers; it increased nutrient utilisation for both growers and finishers; it decreased aerobic bacterial counts in both jejunal and caecal digesta in a dose-dependent manner; it enhanced intestinal villus heights in a dose-dependent manner and made the duodenum villi of the CADNL8 group at 42 d appear as a netted leaf-like structure. CADN is therefore a possible alternative to AGP in broiler feeds.

Lysozyme transgenic goats' milk positively impacts intestinal cytokine expression and morphology

In addition to its well-recognized antimicrobial properties, lysozyme can also modulate the inflammatory response. This ability may be particularly important in the gastrointestinal tract where inappropriate inflammatory reactions can damage the intestinal epithelium, leading to significant health problems. The consumption of milk from transgenic goats producing human lysozyme (hLZ) in their milk therefore has the potential to positively impact intestinal health. In order to investigate the effect of hLZ-containing milk on the inflammatory response, young pigs were fed pasteurized milk from hLZ or non-transgenic control goats and quantitative real-time PCR was performed to assess local expression of TNF-α, IL-8, and TGF-β1 in the small intestine. Histological changes were also investigated, specifically looking at villi width, length, crypt depth, and lamina propria thickness along with cell counts for intraepithelial lymphocytes and goblet cells. Significantly higher expression of anti-inflammatory cytokine TGF-β1 was seen in the ileum of pigs fed pasteurized milk containing hLZ (P = 0.0478), along with an increase in intraepithelial lymphocytes (P = 0.0255), and decrease in lamina propria thickness in the duodenum (P = 0.0001). Based on these results we conclude that consuming pasteurized milk containing hLZ does not induce an inflammatory response and improves the health of the small intestine in pigs.

Swine intestine antimicrobial peptides inhibit infectious bronchitis virus infectivity in chick embryos

Infectious bronchitis virus (IBV), the causative agent of infectious bronchitis, results in respiratory disease, nephritis, and poor egg production and quality in chicken. Antimicrobial peptides possess potent antimicrobial activities and are regarded as promising therapeutic alternatives in the fight against microorganisms. To assess the in vitro antiviral activity of swine intestine antimicrobial peptides (SIAMP) against IBV, 45 chick embryos were randomly assigned into 3 groups, 15 for each group. Embryos in group 1 were inoculated with IBV. Group 2 was inoculated with SIAMP-IBV intermixture. Group 3 was used as a control and inoculated with sterile PBS. Allantoic fluid was collected for hemagglutination titer assay. In addition, weight gain, mortality, and pathological changes for each group were recorded. The results showed that no distinct pathological changes were found in chick embryos after they were inoculated with SIAMP-IBV intermixture and the mortality was reduced remarkably compared with the IBV-infected group. Weight gain of embryos in the SIAMP-IBV intermixture group was significantly higher than the IBV-infected embryos (P < 0.01), which was also higher than the control group (P < 0.05). Furthermore, the hemagglutination titer in the SIAMP-IBV group was significantly lower than that in the IBV-infected group (P < 0.01). These results indicated that SIAMP can inhibit virus replication and reduce tissue injury caused by IBV.