Molecular mechanism of enhancing the immune effect of the Newcastle disease virus vaccine in broilers fed with Bacillus cereus PAS38.

The aim of this study was to explore the molecular mechanism of enhancing the immune effect of the Newcastle disease virus (NDV) vaccine in broilers fed with Bacillus cereus PAS38. The results showed that the NDV antibody titer of broilers in the treatment group supplemented with B. cereus PAS38 was higher than that of the control group, and the difference was significant at 28 days of age (P < 0.05). The spleen, thymus and bursa of fabricius of 42-day-old broilers were quickly collected to construct a differentially expressed gene library of suppression subtractive hybridization (SSH). A total of 31 immune-related differentially expressed genes were screened from three immune organs, of which 15 were up-regulated and 16 were down-regulated. After silencing the up-regulated genes MIF, CD74, DOCK2 and KLHL6, the expression levels of cytokines (Akirin2, NF-κB, IL-2, IL-4, IL-6, IFN-γ and TNF-α) in lymphocytes were reduced to varying degrees. B. cereus PAS38 might be involved in the proliferation, differentiation, activation, migration of B lymphocytes and vaccine antigen presentation by up-regulating the expression of MIF, CD74, DOCK2, KLHL6 and other genes. Moreover, it also stimulated plasma cells to produce immunoglobulins and specific antibodies, thereby improving the humoral immune function of broilers and enhancing the immune effect of the NDV vaccine.

Mulberry leaf polysaccharide supplementation contributes to enhancing the respiratory mucosal barrier immune response in Newcastle disease virus-vaccinated chicks.

Despite high global vaccination coverage, Newcastle disease (ND) remains a constant threat to poultry producers owing to low antibody levels. Given the respiratory mucosa is the important site for Newcastle disease virus (NDV) vaccination, enhancing respiratory mucosal immunity may help control ND. Our previous study showed that mulberry leaf polysaccharide (MLP) is very promising in delivering a robust balanced immune response, but the effects of it on respiratory immunity in chicks are unknown. In this study, we evaluated the potential of MLP to activate respiratory mucosal immunity and revealed the possible mechanism of MLP as an immunopotentiator for ND vaccines. Chicks were randomly divided into 5 groups: blank control, vaccination control (VC), and low-, middle-, and high-dose MLP (MLP-L, MLP-M, and MLP-H) (n = 30). The serum results of humoral and cell-mediated immune responses showed significant increases in NDV hemagglutination inhibition antibody titer, IgG and IgA antibody levels, and the T-lymphocyte population in the MLP-M group compared with the VC group. Validation of results also indicated remarkable increases in tracheal antibody-mediated immunity and a mucosal immune response in the MLP-M group. Furthermore, the upregulation of TLR7 revealed a possible mechanism. Our findings provided evidence to consider MLP as a potential mucosal vaccine adjuvant candidate against ND in chickens.

Synergistic use of florfenicol and Salvia miltiorrhiza polysaccharide can enhance immune responses in broilers.

To explore the effect of florfenicol (FFC) combined with Salvia miltiorrhiza polysaccharide (SMPs) on immune function of Broilers. One hundred and twenty-one-day-old chicks were chosen and divided into 6 groups. The group A received standard basal diet only, the group B received a basal diet with FFC (0.15 g/L diet), and the group C, D, E received a basal diet with FFC (0.15 g/L diet) and SMPs (1.25 g/L, 2.5 g/L, 5 g/L diet)，the group F received a basal diet with SMPs (5 g/L diet). FFC can significantly inhibit the growth performance of broilers, but has no significant damage to the immune function of broilers. The combination of FFC and SMPs can improve the growth performance of broilers, increase the number of leukocyte subtypes in blood (P < 0.05), increase the number of Newcastle disease (ND) and avian influenza (AI) antibodies in blood, the number of immunoglobulins, and the content of cytokines (P < 0.05). In addition, it significantly improve the lymphocyte conversion rate of broiler peripheral blood (P < 0.05). So that, synergistic use of FFC and SMPs can enhance immune responses in Broilers.

Sunflower seed oil containing ginseng stem-leaf saponins (E515-D) is a safe adjuvant for Newcastle disease vaccine.

Vaccination is an effective method to prevent Newcastle disease (ND) in chickens. Marcol 52 and #10 white oil are mineral-based adjuvants and can be found in commercial inactivated ND virus vaccines. The present study demonstrated that a vegetable origin oil E515-D had lower polycyclic aromatic hydrocarbons and higher flash point than the commercial products Marcol 52 and #10 white oil. E515-D could be mixed with an aqueous phase containing ND virus antigen to form a stable water-in-oil vaccine emulsion and exhibited more potent adjuvant effects on the immune response than Marcol 52 and #10 white oil. Moreover, the absorption of E515-D-adjuvanted vaccine was faster than absorption of Marcol 52- and #10 white oil-adjuvanted vaccines when ND virus vaccines were injected in broilers. Therefore, E515-D was safe and could be a suitable adjuvant used in vaccines for food animals. In addition，E515-D is not easy to be flammable during shipping and storage owing to its higher flash point.

The Immunogenicity of a Novel Chimeric Hemagglutinin-Neuraminidase-Fusion Antigen from Newcastle Disease Virus by Oral Delivery of Transgenic Canola Seeds to Chickens.

Newcastle disease (ND) is considered as one of the most devastating infectious diseases targeting domestic birds and has considerable threat to the commercial poultry production. Two surface glycoproteins, hemagglutinin-neuraminidase (HN) and fusion (F), act as antigens in the virus structure and also play important roles in infecting host cells. In the current study, the expression of the chimeric HN-F protein in canola seeds and its immunogenicity in chickens were investigated. The HN-F gene was cloned downstream of the fatty acid elongase 1 (FAE1) promoter in the binary expression vector, pBI1400-HN-F, and introduced into rapeseed (Brassica napus L.) using Agrobacterium-mediated transformation. The amount of the HN-F glycoprotein was estimated up to 0.18% and 0.11% of the total soluble protein (TSP) in transgenic seeds and leaves of canola, respectively. Confirmatory analyses of 36 transgenic lines revealed that the HN-F gene was integrated into the genome. Subsequently, HN-F protein could be expressed and accumulated in the seed tissue. Specific pathogen-free (SPF) chickens immunized orally with recombinant HN-F showed a significant rise in specific and hemagglutination inhibition (HI) antibodies 35 to 42 days post the first administration. The results implied the potential of transgenic canola seed-based expression for oral delivery of NDV immunogenic glycoproteins.

Effect of the oral administration of astragalus polysaccharides on jejunum mucosal immunity in chickens vaccinated against Newcastle disease.

Astragalus polysaccharides (APS) are a traditional Chinese medicine with a therapeutic effect by enhancing immune function; however, the underlying functional mechanism is still unclear. The aim of the present study was to determine the effect of oral administration of APS on jejunum mucosal immunity in chickens vaccinated against Newcastle disease (ND). One-day-old Hy-Line male chickens were divided into five groups of 20 chicks each: three APS groups, one vaccinated control (VC) group and one non-vaccinated negative control (NC) group. On d 10, the APS groups were orally administered 0.5 mL of APS at doses of 1 mg/mL (APSL), 2 mg/mL (APSM) and 4 mg/mL (APSH) daily for 4 consecutive days. The chicks in the control groups were administered 0.5 mL saline for those 4 days. All groups except NC were administered a ND virus (NDV) vaccine on day 14. The jejunum was removed from 4 randomly selected chickens of each group at 1, 7, 14 and 28 days after vaccination. The jejunal villus height (VH) and crypt depth (CD) were measured and the VH:CD ratio calculated. Immunohistochemistry was used to analyze the differences of IgA+ cells in the jejunum. NDV specific secretory IgA (sIgA) levels in jejunal contents were detected using an indirect ELISA. At most time points, VH:CD ratios, number of IgA+ cells, and sIgA levels were significantly higher in the APS groups than those in VC and NC groups, but there were little differences among the three doses of APS groups. These results indicate that oral administration of APS could enhance the intestinal mucosal immune function of chickens, and APS could be used as a vaccine enhancer.

Combined adjuvant effect of ginseng stem-leaf saponins and selenium on immune responses to a live bivalent vaccine of Newcastle disease virus and infectious bronchitis virus in chickens.

Vaccination with a live bivalent vaccine of Newcastle disease virus (NDV) and infectious bronchitis virus (IBV) is a routine practice in poultry industry in China. This study was designed to evaluate ginseng stem-leaf saponins (GSLS) in combination with selenium (Se) for their adjuvant effect on the immune response to vaccination against NDV and IBV in chickens. A live bivalent vaccine of NDV and IBV was diluted in saline solution containing GSLS or Se or both and used to immunize chickens via a intraocular-and-intranasal route. Results showed that GSLS promoted significantly higher NDV- and IBV-specific antibody responses with the highest antibody response detected in GSLS-Se group. The increased antibody was capable of neutralizing NDV and IBV. In addition, GSLS-Se enhanced lymphocyte proliferation and production of IFN-γ and IL-4. More importantly GSLS-Se was found to promote early production and prolong the duration of the antibody responses. In order to improve the efficacy of vaccination in chicken flocks, the diluent containing GSLS-Se deserves further studies to evaluate its effect on other chicken vaccines.

Effects of beta-1,3-glucan (AletaTM) on vaccination response in broiler chickens.

This 42-day study evaluated the effects of dietary supplementation with ß-1,3-glucan (Aleta™) on the vaccination response to Newcastle disease virus (NDV), avian infectious bronchitis virus (IBV), and infectious bursal disease (IBD) in a non-challenged environment. This trial included 600 chicks (all vaccinated with IBD at the hatchery) which were assigned to 1 of 3 treatments: vaccination (NDV, IBV), no vaccination, or vaccination combined with feed supplemented with Aleta (100 g/MT of feed). The vaccination with Aleta treatment group showed a trend for improved FCR that was not statistically significant. Control birds that were not vaccinated for IBV had significantly lower IBV titers on day 21 compared to birds that were vaccinated (both with and without Aleta). Surprisingly, there was significant separation among treatment groups for NDV titer levels, especially on day 21, where birds vaccinated and supplemented with Aleta had significantly higher titer levels compared to vaccination alone or no vaccination at all. Critically, only 14% of the birds receiving the vaccine plus Aleta had titer levels below the critical titer threshold for immunity compared to 28% of the birds receiving the vaccine alone and 40% of the unvaccinated birds. This suggests that Aleta supplementation may help to improve the vaccination response by birds, especially for NDV.

Dietary inclusion of mushroom (Flammulina velutipes) stem waste on growth performance and immune responses in growing layer hens.

BACKGROUND: Medicinal mushrooms contain biologically active substances that can be used as an immune-modulating agent in poultry. The present study aimed to investigate the effects of Flammulina velutipes mushroom waste (FVW) on performance, immune response and serum immunity in growing layer hens. RESULTS: No significant differences (P > 0.05) were observed with respect to average daily feed intake, body weight gain and feed conversion ratio among the experimental groups during the entire study period (1-70 days). Antibody titers against Newcastle disease and infectious bronchitis were higher (P < 0.05) in the FVW fed groups than in the control and antibiotic groups. On day 28, serum immunoglobulin (Ig)A and IgG were higher (P < 0.05) in the 6% FVW group than in the control and antibiotic fed groups. On day 70, serum IgA was higher (P < 0.05) in FVW fed groups than in the control group; IgG was higher (P < 0.05) in the FVW groups than in the control and antibiotic groups. However, IgM was higher (P < 0.05) in both the 4% and 6% FVW groups than in the control and antibiotic groups for both experimental periods. Serum cytokine interleukin (IL)-2 and tumor necrosis factor-α concentrations were significantly higher (P < 0.05) in both the 4% and 6% FVW grousp than in the control and antibiotic groups; IL-4 was significantly higher (P < 0.05) in the FVW groups than in the control group; and IL-6 was significantly higher (P < 0.05) in the 6% FVW group than in the control and antibiotic groups. CONCLUSION: FVW at the 6% level can be used as a potential phytogenic feed stuff in growing layer hen rations with respect to improving the immune response without affecting normal weight gain. © 2018 Society of Chemical Industry.

Oral administration of tea saponins to relive oxidative stress and immune suppression in chickens.

The present study was designed to evaluate the effects of tea saponins on oxidative stress induced by cyclophosphamide in chickens. One hundred twenty chickens were randomly divided into 5 groups. Groups 3 to 4 received intramuscular injection of cyclophosphamide to induce oxidative stress and immunosuppression. After that, groups 2 and 4 were orally administered tea saponins in drinking water for 7 d. Then, groups 1 to 4 were immunized with a live, bivalent vaccine of Newcastle disease virus and infectious bronchitis virus. Blood samples were collected for analysis of oxidative parameters and specific antibody titers, and splenocytes were prepared for lymphocyte proliferative assay. The results showed that administration of tea saponins significantly increased total antioxidant capacity, total superoxide dismutase, catalase, glutathione peroxidase, glutathione, ascorbic acid, and α-tocopherol, and decreased malondialdehyde and protein carbonyl. Enhanced immune responses, such as lymphocyte proliferation induced by concanavalin A and lipopolysaccharides, and serum Newcastle disease virus- and infectious bronchitis virus-specific antibodies were also observed in chickens injected with or without cyclophosphamide. In addition, no side effects were found in chickens throughout the study. Therefore, tea saponins may be a potential agent to improve imunosuppression induced by oxidative stress in chickens.

Effects of pidotimod soluble powder and immune enhancement of Newcastle disease vaccine in chickens.

The aims of this study were to prepare pidotimod (PDM) soluble powder and to investigate the immune enhancement properties of PDM in chickens vaccinated with Newcastle disease virus vaccine. In vivo experiment, 360 6-day-old chickens were averagely divided into 6 groups. The chickens, except blank control (BC) group, were vaccinated with Newcastle disease vaccine (NDV). At the same time of the vaccination, the chickens in three PDM groups were given water with PDM for 5days, respectively, with the PDM at low, medium and high concentrations (0.25g/L, 0.5g/L, 1g/L), in control drug group was treated with 0.2ml/PDM dose via drinking water, in vaccination control (VC) and BC group, with equal volume physiological saline, once a day for five successive days. On days 14, 21 and 28 after the vaccination, the growth performance, the lymphocyte proliferation, serum antibody titer, the CD4/CD8 cell ratios and interleukin-2 (IL-2) and interferon-gamma (IFN-γ) were measured. The results showed that PDM at suitable dose could significantly promote growth performance, lymphocyte proliferation, enhance serum antibody titer, CD4/CD8 cell ratios and improve serum IL-2 and IFN-γ concentrations. It indicated that PDM could significantly improve the immune efficacy of Newcastle disease vaccine using doses of 0.5g/L, these results are consistent with the drug acting as an immunopotentiator.

Effects of dietary fat source and supplemental lysophosphatidylcholine on performance, immune responses, and ileal nutrient digestibility in broilers fed corn/soybean meal- or corn/wheat/soybean meal-based diets.

Two separate experiments were conducted to investigate the effect of different fat sources and a supplemental exogenous emulsifier (lysophosphatidylcholine, LPC) on growth performance, antibody production titers, and ileal nutrient digestibility in broiler chicks fed with different basal diets. A total of 288 one-day-old Ross 308 chicks were used for each trial (6 dietary treatments based on 3 × 2 factorial arrangements of treatments in both trials) with 4 replicates of 12 birds each. Dietary treatments consisted of 3 different fat sources (soy oil, SO; soy free fatty acids, SFFA; and palm fat powder, PFP) and 2 LPC levels (0 and 0.1% of diet), which were evaluated with 2 different basal diets (corn/soybean meal-based diets in Exp. 1, or corn/wheat/soybean meal-based diets in Exp. 2). In Exp. 1, average daily feed intake (ADFI) was increased (P < 0.01) in birds fed PFP diets compared with those fed SO or SFFA diets. Although supplemental LPC decreased (P < 0.01) ADFI, the birds fed SFFA diets had the greater ADFI at the presence of LPC (fat source × LPC, P < 0.01). Dietary supplementation of LPC caused a 4.6% improvement (P < 0.001) in average daily weight gain (ADWG) and consequently improved (P < 0.01) feed conversion ratio (FCR). Supplemental LPC was more effective in increasing ADWG in SFFA-containing diets, resulted in a significant (P < 0.01) dietary fat source × LPC interaction. Dietary inclusion of LPC increased (P < 0.01) bursa weight and improved (P < 0.05) antibody production titers against sheep red blood cells and Newcastle disease virus during primary responses. Ileal digestibility of ether extract (EE) was improved (P < 0.05) in birds fed diets containing SO as compared with those fed PFP diets; dietary LPC supplementation, however, had no marked effect on ileal nutrient digestibility. In Exp. 2, ADWG was greater (P < 0.05) in birds fed SO-containing diets compared with PFP-supplemented broiler chicks. Furthermore, dietary supplementation with LPC improved (P < 0.05) FCR value by 2.1%. Relative thymus weight was greater (P < 0.05) in birds fed LPC-supplemented diets than those fed unsupplemented diets. Supplemental LPC increased (P < 0.05) Gumboro antibody titer, and the lowest antibody response was allotted to the birds fed PFP diets. The greatest (P < 0.05) EE digestibility was assigned to the birds fed SO and SFFA diets. The present findings showed that birds fed SFFA-containing diets had similar performance as SO birds, and supplemental LPC improved overall performance especially in SFFA-fed birds.

Modification of lily polysaccharide by selenylation and the immune-enhancing activity.

Lily polysaccharide (LP) was extracted, purified and selenizingly modified by HNO3-Na2SeO3 method according to L9(3(4)) orthogonal design. Nine selenizing LPs, sLP1-sLP9, were obtained and their immune-enhancing activities were compared taking unmodified LP as control. The results in vitro test showed that sLP6 presented the strongest activity in promoting lymphocytes proliferation in single and synergetic with PHA, and the relative expression level of IL-2, IL-6 and IFN-γ mRNA of chicken peripheral lymphocytes. The results in vivo test showed that sLP6 could promote lymphocytes proliferation and enhance the serum antibody titers and serum IL-2, IL-6, IFN-γ contents more significantly than LP in chickens vaccinated with Newcastle Disease (ND) vaccine. These results indicate that polysaccharide selenizing can significantly enhance the immune-enhancing activity of LP and the optimal modification conditions are 400 mg of Na2SeO3 per 500 mg of LP, the reaction temperature of 70 °C and the reaction time of 6 h.

Growth, immune, antioxidant, and bone responses of heat stress-exposed broilers fed diets supplemented with tomato pomace.

A study was conducted to investigate the effects of supplementation of dried tomato pomace (DTP) on growth performance, relative weights of viscera, serum biological parameters, antioxidant status, immune response, and bone composition of broilers exposed to a high ambient temperature. A total of 352 one-day-old male broiler chickens were randomly divided into four groups consisting of four replicates with 22 birds each. One group was reared under the thermoneutral zone and fed a corn-soybean meal basal diet. The other three groups were subjected to a cyclic heat stress from 29 to 42 days of age (34 ± 1 °C, 55 % RH, 5 h/day). These birds were fed corn-soybean meal basal diet or the same diet supplemented with 3 % DTP (420 mg lycopene/kg diet) or 5 % (708 mg lycopene/kg diet) of DTP. Blood samples were collected on days 28 and 42, and the birds were slaughtered at the same times. Supplementation of 5 % of DTP increased body weight and production index and decreased feed conversion ratio during 1-28 days of age. On day 28, the broilers supplemented with 5 % DTP had lower serum triglycerides and higher high-density lipoprotein (HDL) cholesterol concentration than those on the other dietary treatments. The activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) were higher and the concentration of malondialdehyde (MDA) was lower in the broilers fed 5 % TP than those of the broilers fed other diets at 28 days of age. The effects of heat stress (HS) were impaired body weight, enhanced serum activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lipase, and MDA concentration while reducing the activities of GPx and SOD. Dried tomato pomace supplementation did not influence growth performance under HS but ameliorated the negative effects of HS on the serum enzyme activities, GPx activity, and lipid peroxidation. Heat stress did not change the relative weights of the lymphoid organs but reduced the total and IgG titers for secondary antibody response to sheep red blood cells and titer against Newcastle disease virus and increased the heterophil/lymphocyte ratio. The supplementation with 5 % of DTP completely alleviated the negative effects of HS on immune responses. The ash, Ca, and P contents of the tibia bone were decreased under HS. The ash and Ca contents of the tibia were not significantly different between thermoneutral and heat-stressed broilers supplemented with 5 % DTP. In conclusion, dietary supplementation of DTP, particularly 5 % DTP, to broiler diet attenuated the detrimental effects of HS on the activities of serum enzymes, oxidative status, immune response, and bone composition.

Selection, characterisation and evaluation of potential probiotic Lactobacillus spp. isolated from poultry droppings.

Aim of the present study was to characterise and evaluate probiotic potential of lactobacilli isolated from indigenous poultry. Lactobacilli were isolated from poultry droppings and identified by genus specific polymerase chain reaction and 16S rRNA gene sequencing. Isolates were characterised in vitro by their ability to tolerate low pH and bile salts, phytase activity, antimicrobial activity, antibiotic susceptibility profile, and autoaggregation and coaggregation with poultry gut pathogens. In vivo evaluation of selected isolates was done by their effect on the body weight gain and immune response of broiler chicks. Total of 90, one-day old chicks, were randomly divided in 9 groups and given selected lactobacilli alone and in combinations (108 cfu/bird, daily) from day 7 to day 35. Body weight gain and humoral immune response to New Castle Disease Virus (NDV) vaccine were determined weekly. Three lactobacilli isolates (SMP52, SMP64 and SMP70) were selected as potentially probiotic bacteria on the basis of in vitro characterisation and identified as Lactobacillus crispatus, Lactobacillus casei and L. crispatus, respectively. Chicks supplemented with 'SMP52', 'SMP64', 'SMP70' and 'SMP64+SMP70' and a commercial probiotic product (Protexin) showed significantly higher mean weight gain per bird (1,584±35.2, 1,629±30.6, 1,668±34.7, 1,619±29.5 and 1,576±31.7 g/bird, respectively) as compared to negative control group (1,394±26.7 g/bird), on day 35. SMP 70 also showed significantly higher geometric mean titre against NDV vaccine at day 21 as compared to negative control. It is concluded that L. crispatus SMP52, L. casei SMP64 and L. crispatus SMP70 are potential probiotic candidates which alone or in different combinations may increase body weight of broilers.

Improved immune responses to a bivalent vaccine of Newcastle disease and avian influenza in chickens by ginseng stem-leaf saponins.

Our previous investigation demonstrated that ginseng stem-leaf saponins (GSLS) derived from the stems and leaves of Panax ginseng C.A. Meyer promoted humoral and gut mucosal immunity in chickens vaccinated with live infectious bursa disease vaccine. The present study was designed to evaluate the effect of GSLS on the immune response to a bivalent inactive vaccine of Newcastle disease (ND) and avian influenza (AI) in chickens immunosuppressed by cyclophosphamide (Cy). One hundred and sixty-eight specific-pathogen-free (SPF) chickens were randomly divided into 7 groups, each containing 24 birds. Chickens in groups 3-7 received intramuscular injection of Cy at 100mg/kg BW for 3 days to induce immunosuppression. Groups 1 and 2 were injected with saline solution in the same way as groups 3-7. Following injection of Cy, groups 4-7 were orally administrated GSLS (2.5, 5 and 10mg/kg BW) or astragalus polysaccharide (APS) (200mg/L) in drinking water for 7 days; groups 1-3 were not medicated and served as control birds. After administration of GSLS or APS, groups 2-7 were subcutaneously injected with a bivalent inactive vaccine of ND and AI. After that, serum was sampled for detecting antibody titers by HI, spleen was collected for lymphocyte proliferation assay, and duodenum tissues were collected for measurement of IgA-secreting (IgA+) cells and intestinal intraepithelial lymphocytes (iIELs). The results showed that injection of Cy significantly suppressed immunity in chickens; oral administration of GSLS before immunization recovered splenocyte proliferation induced by ConA and LPS, and the numbers of IgA+ cells and iIELs as well as the specific antibody response to a bivalent inactive vaccine of ND and AIin immunosuppressed chickens treated with Cy. Therefore, GSLS may be the potential agent to improve vaccination in immunosuppressed chickens.

Improved performance and immunological responses as the result of dietary genistein supplementation of broiler chicks.

The present study aimed to investigate the effect of supplemental genistein (an isoflavonoid) on performance, lymphoid organs' development, and cellular and humoral immune responses in broiler chicks. A total of 675-day-old male broiler chicks (Ross 308) were randomly assigned to the five replicate pens (15 chicks each) of nine experimental diets. Dietary treatments included a negative (not-supplemented) control diet, two positive control groups (virginiamycin or zinc-bacitracin, 20 mg/kg), and diets containing 10, 20, 40, 80, 160 and 320 mg/kg of genistein. The cutaneous basophil hypersensivity (CBH) test was measured at day 10 of age after toe web injection with phytohemagglutinin-P. In addition, sera samples were collected after different antigen inoculations to investigate antibody responses. At day 28 of age, three randomly selected birds from each pen were euthanized to evaluate the relative weights of lymphoid organs. Results showed that dietary supplementation of both antibiotics increased (P<0.01) feed intake during 1 to 42 days of age. Furthermore, daily weight gain was influenced (P<0.01) by dietary treatments throughout the trial, so that the birds fed on antibiotics and 20 to 80 mg/kg genistein diets revealed the greater weight gains compared with other experimental groups. The best (P<0.05) feed conversion ratio assigned to the birds fed on diets containing antibiotics and moderate levels (40 to 80 mg/kg) of genistein. Although the relative weights of thymus (P<0.05) and bursa of Fabricius (P<0.01) were greater in birds fed on genistein-supplemented diets compared with antibiotics-supplemented birds, the spleen weight was not affected by experimental diets. Similarly, CBH response and antibody titers against Newcastle and infectious bronchitis disease viruses were markedly (P<0.05) greater in chicks fed on diets supplemented with 20 to 80 mg/kg of genistein. Interestingly, the higher dosages of genistein suppressed CBH and antibody responses to the levels seen by control and antibiotics chicks. Dietary inclusion of genistein increased (P<0.05) lymphocytes and subsequently reduced (P<0.01) heterophil to lymphocyte ratio. The present findings indicate that dietary genistein supplementation at the levels of 20 to 80 mg/kg not only improves growth performance, but also could beneficially affect immunological responses in broiler chicks.

Immunomodulatory effects of Taishan Pinus massoniana pollen polysaccharide and propolis on immunosuppressed chickens.

Co-infection of reticuloendotheliosis virus (REV) and avian leukosis virus subgroup J (ALV-J), which can cause suppressed immunity and vaccination failure, frequently occurs in chicken flocks in China. Taishan Pinus massoniana pollen polysaccharide (TPPPS) and propolis (PP) have been proven to possess immune modulatory effects and improve the immune effects of vaccines. This study aimed to investigate the immune modulatory ability of TPPPS and PP on chickens co-infected with immunosuppressive viruses. Prior to the study, chickens were artificially established as REV and ALV-J co-infection models. Four randomly assigned groups of these immunosuppressed chickens were successively administered with TPPPS, PP, mixture of TPPPS and PP (TPPPS-PP), or phosphate-buffered saline (PBS) for three days. At nine days old, the four immunosuppressed groups, as well as one normal group, were inoculated with the attenuated Newcastle disease (ND) vaccine. During the monitoring period, the indices of immune organ weight, lymphocyte transformation rates, CD4(+) and CD8(+) T-lymphocyte counts in peripheral blood, IL-2 and IFN-γ secretions, serum antibody titers of ND vaccine, and viral loads in spleens were determined. The results showed that chickens administered with TPPPS, PP, or TPPPS-PP could significantly enhance the levels of the above immune parameters compared to chickens in the PBS group. We observed the strongest immunity in the TPPPS-PP group, which indicates that the combination of TPPPS and PP versus TPPPS or PP alone, could generate better effects on improving the immune system effectiveness of immunosuppressed chickens.

Effect of dietary vitamin A on reproductive performance and immune response of broiler breeders.

The effects of dietary vitamin A supplementation on reproductive performance, liver function, fat-soluble vitamin retention, and immune response were studied in laying broiler breeders. In the first phase of the experiment, 1,120 Ross-308 broiler breeder hens were fed a diet of corn and soybean meal supplemented with 5,000 to 35,000 IU/kg vitamin A (retinyl acetate) for 20 weeks. In the second phase, 384 Ross-308 broiler breeder hens were fed the same diet supplemented with 5,000 to 135,000 IU/kg vitamin A (retinyl acetate) for 24 weeks. The hens' reproductive performance, the concentrations of vitamins A and E in liver and egg yolk, liver function, mRNA expression of vitamin D receptor in duodenal mucosa, antibody titers against Newcastle disease virus vaccine, and T-cell proliferation responses were evaluated. Supplementation of vitamin A at levels up to and including 35,000 IU/kg did not affect reproductive performance and quadratically affected antibody titer to Newcastle disease virus vaccine (p<0.05). Dietary addition of vitamin A linearly increased vitamin A concentration in liver and yolk and linearly decreased α-, γ-, and total tocopherol concentration in yolk (p<0.01) and α-tocopherol in liver (p<0.05). Supplementation of vitamin A at doses of 45,000 IU/kg and above significantly decreased egg weight, yolk color, eggshell thickness and strength, and reproductive performance. Dietary vitamin A significantly increased mRNA expression of vitamin D receptor in duodenal mucosa (p<0.05), increased aspartate amino transferase activity, and decreased total bilirubin concentration in serum. Supplementation of vitamin A at 135,000 IU/kg decreased the proliferation of peripheral blood lymphocytes (p<0.05). Therefore, the maximum tolerable dose of vitamin A for broiler breeders appears to be 35,000 IU/kg, as excessive supplementation has been shown to impair liver function, reproductive performance, and immune response.

Forsythia suspensa extract attenuates corticosterone-induced growth inhibition, oxidative injury, and immune depression in broilers.

Forsythia suspensa extract (FSE) has been demonstrated to attenuate physiological stress induced by high temperature or high stocking density. This experiment was conducted with 144 male Arbor Acre broilers (1-d-old, weighing 42.7 ± 1.7 g) to determine the effects of FSE on performance, nutrient digestibility, antioxidant activities, serum metabolites, and immune parameters for birds treated with corticosterone (CS). The birds were randomly allotted to 1 of 4 treatments in a 2 × 2 factorial arrangement that included FSE supplementation (0 or 100 mg/kg) and CS administration (0 or 20 mg/kg of diet for 7 consecutive days starting on d 14). The feeding program consisted of a starter diet from d 1 to 21 and a finisher diet from d 22 to 42. Corticosterone administration decreased (P < 0.01) ADG and impaired (P < 0.01) feed conversion ratio in both phases and overall, which were alleviated (P < 0.01) by dietary FSE supplementation in the finisher phase and overall. At d 21, CS administration caused decreases (P < 0.05) in the apparent digestibility of energy, relative weight of bursa and thymus, total antioxidant capacity, superoxide dismutase (SOD) activity, and antibody titers to Newcastle disease virus (NDV); however, serum malondialdehyde and uric acid were increased. All of these changes were attenuated (P < 0.05) by dietary FSE supplementation. At d 42, FSE supplementation improved (P < 0.05) the apparent digestibility of DM and CP, relative weights of bursa, SOD activity, and antibody titers to NDV, which were impaired by CS administration. Interactions (P < 0.05) were noted between CS and FSE for ADG and feed conversion ratio in the finisher phase and overall, as well as total antioxidant capacity, SOD activity, uric acid, and antibody titers to NDV at d 21, as well as relative weights of thymus at d 42. In conclusion, dietary FSE supplementation enhanced nutrient digestibility and performance of broiler possibly by reducing oxidative stress and immune depression challenged by CS.