Chicken egg yolk antibodies (IgY) as non-antibiotic production enhancers for use in swine production： a review

In recent years, the use of in-feed antibiotics for growth and disease prevention in livestock production has been under severe scrutiny. The use and misuse of in-feed antibiotics has led to problems with drug residues in animal products and increased bacterial resistance. Chicken egg yolk antibodies （IgY） have attracted considerable attention as an alternative to antibiotics to maintain swine health and performance. Oral administration of IgY possesses many advantages over mammalian IgG such as cost-effectiveness, convenience and high yield. This review presents an overview of the potential to use IgY immunotherapy for the prevention and treatment of swine diarrhea diseases and speculates on the future of IgY technology. Included are a review of the potential applications of IgY in the control of enteric infections of either bacterial or viral origin such as enterotoxigenic Escherichia coil, Salmonella spp., rotavirus, porcine transmissible gastroenteritis virus, and porcine epidemic diarrhea virus. Some potential obstacles to the adoption of IgY technology are also discussed.

A rapid and convenient dot-immunobinding assay for chicken egg-yolk antibodies

The dot-immunobinding assay was applied to investigate the characteristics of chicken egg yolk antibodies. This method of assay was proved to be a rapid and simple method to demonstrate and characterize the egg-yolk antibody IgY in comparison with the traditional ELISA assay. By using the BandScan software, the gray scale value of dots and the background could be determined. According to the intensity of dots (gray scale value) compared to the standard sample of 10μg, how much IgY remained can be determined in a shorter time.

Application of high-titred IgY antibodies in orthopox virus diagnostics

Layer chickens were immunized with three species of inactivated orthopox virus （vaccinia virus, calpox virus and cowpox virus）. Antibodies （IgY） were purified from egg yolks by improved polyethylene glycol precipitation. The development of IgY directed against orthopox virus antigens was followed by immunofluorescence assay, plaque reduction neutraliztion test and immunoelectron microscopy. Cross-reactivity of two IgY antibodies with cells infected by the different strains of the pox viruses was also investigated by different methods （immunofluorescence assay, plaque reduction neutraliztion test and Western blot）. Even in very high dilutions in immunofluorescence assay （titres up to 1：10^6 and 1：10^5, respectively） and persisted on a plateau over 10 months after four booster injections, it was showed that anti-vaccinia virus IgY and anti-calpox virus IgY were positive. Neutralizing activity and ultra-structural detection of antigen with gold-labelled antibodies were respectively observed in plaque reduction neutralization test and immunoelectron microscopy. Western blot analysis revealed specific binding of IgY to virus proteins. Thus, there was cross-reactivity between different orthopox viruses. Finally, orthopox virns-specific IgY antibodies bounded magnetic beads （Dynabead） were used to concentration of orthopox viruses. This study suggests that anti-pox virus IgY could serve as a useful tool for orthopox viruses diagnosis.

Alternatives to antibiotics as growth promoters for use in swine production:a review

In the past two decades, an intensive amount of research has been focused on the development of alternatives to antibiotics to maintain swine health and performance. The most widely researched alternatives include probiotics, prebiotics, acidiflers, plant extracts and neutraceuticals such as copper and zinc. Since these additives have been more than adequately covered in previous reviews, the focus of this review will be on less traditional alternatives. The potential of antimicrobial peptides, clay minerals, egg yolk antibodies, essential oils, eucalyptus oil-medium chain fatty acids, rare earth elements and recombinant enzymes are discussed. Based on a thorough review of the literature, it is evident that a long and growing list of compounds exist which have been tested for their ability to replace antibiotics as feed additives in diets fed to swine. Unfortunately, the vast majority of these compounds produce inconsistent results and rarely equal antibiotics in their effectiveness. Therefore, it would appear that research is still needed in this area and that the perfect alternative to antibiotics does not yet exist.

Dietary supplementation of sulfur amino acids improves intestinal immunity to Eimeria in broilers treated with anti-interleukin-10 antibody

Oral antibody to interleukin-10(anti-IL-10)enhances the intestinal immune defense against Eimeria.The sulfur amino acids methionine and cysteine(MtC)play essential roles in inducing and maintaining protective immune responses during intestinal infections.Hence,increased dietary MtC may support the anti-IL-10-induced intestinal immunity to Eimeria.Broilers(n=640)were arranged in a 2×2×2 factorial design with 2 levels of each of the 3 main factors:dietary standardized ileal digestible(SID)MtC levels(0.6%or 0.8%),dietary anti-IL-10 supplementation(with or without),and coccidiosis challenge(control or challenge).Briefly,the broilers were supplied with either 0.6%or 0.8%SID MtC,each with or without anti-IL-10(300 mg/kg),from d 10 to 21.On d 14,broilers from each diet were gavaged with either PBS or Eimeria.The resulting Eimeria infection induced fecal oocyst shedding and intestinal lesions.Broilers fed 0.8%SID MtC(main effects,P≤0.05)had decreased feed-to-gain ratio,increased duodenum and cecum luminal anti-Eimeria IgA titers,and decreased fecal oocyst counts,when compared to 0.6%SID MtC.The supplementation of anti-IL-10(main effects,P≤0.05)increased cecum luminal total IgA concentration and decreased cecum lesions.Interactions(P≤0.05)were detected for growth performance and cecum luminal IFN-γ.Briefly,the highest body weight gain and feed intake were reached in PBS-gavaged broilers fed 0.8%SID MtC with no anti-IL-10 and in Eimeria-challenged broilers fed 0.8%SID MtC with anti-IL-10.In Eimeria-infected broilers,anti-IL-10 increased intestinal luminal IFN-γ and body weight gain only at 0.8%SID MtC.Collectively,anti-IL-10 increased intestinal luminal IFN-γ levels,decreased cecum lesions and restored growth only when fed with adequate amounts of sulfur amino acids.Our findings underscore the importance of providing sufficient essential nutrients to support the anti-IL-10 induced immunity against coccidiosis.