Because the delay of feed post-hatch (PH) has been associated with negative growth parameters, the aim of the current study was to determine the effect of delayed access to feed in broiler chicks on the expression of immune-related genes and select proteins. In addition, an analysis of the correlation between gene expression and components of the gut microbiota was carried out. Ross 708 eggs were incubated and hatched, and hatchlings were divided into FED and NONFED groups. The NONFED birds did not have access to feed until 48 h PH, while FED birds were given feed immediately PH. The ileum from both groups (n = 6 per group) was sampled at embryonic day 19 (e19) and day 0 (wet chicks), and 4, 24, 48, 72, 96, 144, 192, 240, 288, and 336 h PH. Quantitative PCR (qPCR) was carried out to measure the expression of avian interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-18, transforming growth factor (TGF-β), toll-like receptor (TLR)2, TLR4, interferon (IFN)-β, IFN-γ, and avian β-defensins (AvBD) I, 2, 3, 5, 6, 7, 8, 9, and 10. Protein expression of IL-10, IL-1β, IL-8, and IL-18 were measured using ELISAs. A correlation analysis was carried out to determine whether any significant association existed between immune gene expression and components of the ileal luminal and mucosal microbiota. Expression of several immune-related genes (TGF-β, TLR4, IFN-γ, IL-1β, IL-4, IL-6, and AvBDs 8 and 9) were significantly affected by the interaction between feed status and age. The effects were transient and occurred between 48 and 96 h PH. The rest of the genes and four proteins were significantly affected by age, with a decrease in expression noted over time. Correlation analysis indicated that stronger correlations exist among gene expression and microbiota in NONFED birds. The data presented here indicates that delay in feed PH can affect genes encoding components of the immune system. Additionally, the correlation analysis between immune gene expression and microbiota components indicates that a delay in feed has a significant effect on the interaction between the immune system and the microbiota.

Introduction: Coccidiosis negatively affects intestinal health and digestive functions; however, whether butyric acid glycerol ester (BE) can mitigate these negative effects in broiler chickens is unknown. The study objective was to determine the effects of BE on nutrient transporter and intestinal immune genes in chickens infected with Eimeria maxima (EM).Methods: Ross male 708 chicks were fed diets supplemented with 0 (control, C) or 0.25% of BE. On day 21, half the chickens from each feeding group were infected with 0 or 10³ EM sporulated oocysts creating four treatment groups (C, +EM, +BE, and BE + EM; n = 6/treatment group). Jejunal and ileal tissues were collected at days 7 and 10 post-infection (PI).Results: EM infection reduced (P ≤ 0.02) nutrient transporter genes EAAT3, PEPT2, B°AT, GLUT2, GLUT5, and SGLT1 at days 7 PI in the jejunum and ileum and EAAT3, PEPT1, PEPT2, and B°AT at day 10 PI in the jejunum. The supplementation of BE increased CAT1 in the jejunum and PEPT1, GLUT2, and GLUT5 (P ≤ 0.04) in the ileum at day 10 PI. A BE x EM interaction was observed (P ≤ 0.02) where GLUT1 and GLUT2 were increased in the jejunum of +BE compared to C chickens at day 10 PI. Among the immune-related genes, EM reduced (P ≤ 0.0001) IgA in the jejunum but increased (P = 0.004) TGF-β4 in the jejunum and ileum at day 7 PI. The expression of pIgR was reduced, while TLR2 and TLR4 were increased in +EM compared to C chickens at day 7 PI. In addition, IgA was increased (P = 0.01) in the ileum of +BE compared to C chickens at day 10 PI.Conclusion: The results of the study confirmed that Eimeria maxima reduced nutrient transporters and immune-related genes in the jejunum and ileum of chickens. However, although BE increased the expression of some genes in non-challenged chickens, its supplementation did not prevent the reduction in the expression of selected genes caused by EM infection.

The mycotoxin deoxynivalenol (DON) contaminates chicken feed and negatively impacts intestinal health and overall production performance. The objective of this study was to investigate the effects of lactic acid bacteria and DON toxicity on production performance, intestinal morphology and absorptive function, and oxidative stress in broiler chickens. A total of 432 day-old-Ross 308 chicks were assigned to treatments arranged as a 2 × 3 factorial with mycotoxin (0 mg, noM; 5 mg/kg, M) and probiotic [0 cfu/kg, noP; 1.0 × 10⁹ cfu/kg Lactobacillus acidophilus (LA); or 1.0 × 10⁷ cfu/kg FloraMax-PW (FM), made of LA and Pediococcus acidilactici] and raised for 22 days. Body weight, average daily gain, average daily feed intake, and feed conversion ratio (FCR) were not affected (P = 0.130) by mycotoxin or mycotoxin × probiotic interaction for any days. However, FCR was reduced (P = 0.050) in FM compared to noP for days 8-15. Mycotoxin reduced villus height and villus height-to-crypt depth ratio (P = 0.029 and P = 0.027, respectively) in the jejunum. The level of jejunal zonula occludens-2 mRNA was reduced (P = 0.040) in M+noP and M+LA compared to noM+noP, noM+FM, noM+LA, and M+FM chickens. Ileal occludin and zonula occludens-2 mRNA expressions were increased (P < 0.001 and P = 0.011, respectively) by mycotoxin, and claudin-1 expression was increased (P = 0.029) by FM. Immunoglobulin A mRNA expression was increased (P = 0.020) in FM compared to noP while that of polymeric immunoglobulin receptor was increased (P = 0.004) in FM and LA in the ileum. Plasma catalase activity was reduced (P < 0.001) in M+noP compared to other treatments while that of glutathione reductase was increased (P = 0.036) by DON. In conclusion, DON at 5 mg/kg of feed did not affect production performance, but reduced intestinal morphology, which was not prevented by probiotics. The supplementation of FM improved the overall oxidative status in response to DON. In addition, FM improved intestinal immune genes expression in the context of this study.

1. An experiment was conducted to determine differences in the expression of genes encoding intestinal barrier proteins between fast, medium and slow-growing chickens. Chicken breeds Athens Canadian Random Bred (ACRB), Longenecker's Heritage (LHR), RedBro, Hubbard H1 (HH1), Cobb500 and Ross708 were raised from hatch for 35 d.2. Ileal samples were collected at embryonic day E19 (-2 days post-hatch), hatch and d 7, 14, 21, 28 and 35 post-hatch to assess the expression of genes encoding tight junction proteins (claudins, CLDN; occludin, OCLN; zonula occludens, ZO; and junctional adhesion molecules, JAM), mucin (Muc2), immunoglobulin A (IgA), polymeric immunoglobulin receptor (pIgR) and fatty acid binding protein (FABP2).3. Expression of CLDN-1 was increased (p < 0.0001) in LHR compared to Cobb500 while CLDN-5 was increased (p < 0.0001) in ACRB, HH1, RedBro and Ross708 compared to LHR as well as in ACRB compared to Cob500. Occludin was upregulated (p = 0.01) in ACRB and LHR compared to Ross708 at d 14 post-hatch. Expression of ZO-1 was upregulated (p = 0.001) in LHR compared to Ross708, HH1 and Cobb500. Tight junction genes, except CLDN-4, JAM-2 and JAM-3 were downregulated (p < 0.0001) at hatch and d 7 post-hatch. Expression of Muc2 was increased (p < 0.0001) in LHR compared to RedBro and from -2 d to d 7 post-hatch.4. Immunoglobulin A was increased (p = 0.001) in LHR compared to Ross708 and HH1 at -2 d post-hatch and in LHR compared to ACRB, Cobb500 and Ross708 at hatch. In addition, IgA expression was increased in all breeds at d 14 post-hatch while pIgR was upregulated (p = 0.02) in Cobb500 and Ross708 compared to ACRB, HH1, LHR and RedBro at hatch.5. The gene expression patterns suggest that selection for growth may have not induced changes in junctional complexes and immune defence genes. However, the results confirmed that the expression of these genes is age dependent.

Most probiotics possess bile salt hydrolase enzymes and may increase bile acid excretion and negatively affect fat digestion and absorption. Therefore, the study objective was to determine the time course effects of a commercial probiotic (P) FloraMax-B11 (FM) supplementation on bile acid neosynthesis and enterohepatic circulation in broiler chickens. Fertile Ross 708 eggs were incubated under standard commercial conditions. At hatch, chicks (n = 550) were randomly assigned to 5 treatment groups (n = 5 replicates per treatment group) with 22 birds per pen. The 5 treatment groups consisted of: control group (C, normal water from hatch to 35 days of age without supplements); P3, water supplemented with FM for the first 3 days post-hatch followed by normal water until day 35; P10, water supplemented with FM for the first 10 days post-hatch followed by normal water until day 35; P35, water supplemented with FM from hatch to day 35; and AGP, water supplemented with antibiotic growth promoter (AGP) from hatch until day 35. Ileum, liver, and plasma were collected at hatch, days 3, 10, 21, and 35 post-hatch. The relative mRNA expression of genes involved in bile acid synthesis (CYP7A1, CYP8B1, FXR, FGFR4, and FGF19) and transport (ASBT, I-BABP, OSTα, OSTβ, and BSEP) as well as ileal deoxycholic acid and plasma cholic acid were determined. There was no FM and AGP interaction for any of the response criteria. No FM or AGP effects were observed (p > 0.05) for any genes, except FGF19, which expression was increased (p < 0.0001) in AGP compared to P35. No FM or AGP effects were observed (p > 0.05) for levels of deoxycholic and cholic acids. However, all the genes, deoxycholic acid, and plasma cholic acid were affected by age (p < 0.0001). In general, the data indicate that FM did not negatively impact bile acid metabolism and enterohepatic circulation, which appeared to be age dependent. However, more research should be conducted to confirm these results and investigate the effects of FM on bile acid metabolism, fat digestion, and intestinal microbiota in broiler chickens.

Background: Genetic selection has improved feed efficiency and growth in broiler chickens. Intestinal microbiota plays an important role in gut functions and host metabolism; however, it is unclear whether selection for rapid growth has affected intestinal microbiota. The objective of the study was to determine the effects of genetic selection on intestinal microbiota in broiler chickens. Methods: Heritage (Athens Canadian Random Bred: ACRB), slow- and fast-growing (SG, FG) chickens were raised under similar conditions for 35 d. 16S rRNA sequencing was performed on ileal and cecal luminal (IL-L and CE-L, respectively) and mucosal bacterial populations, and data were analyzed using the qiime2 platform, differential abundance, and metabolic pathways. Results: The relative abundance of the genus Turicibacter was elevated ( P < 0.05) at hatch compared to 48 h before hatch; while at species level, Clostridium celatum was increased ( P < 0.05) at hatch. During the post-hatch period, body weight was higher in the SG and FG groups than in the ACRB group at each time point from d 13 to 35. In IL-L, richness (d 14) was lower ( P < 0.05) in ACRB compared to FG and SG lines, respectively. In CE-L, richness and Shannon index were reduced ( P < 0.05) in ACRB compared to FG lines only on d 35. The Shannon index was significantly ( P < 0.05) lower in ACRB birds compared to FG birds on d 35. The relative abundance of genus Escherichia was higher ( P < 0.05) in SG compared to other lines. FG birds were characterized by the highest ( P < 0.05) Streptococcus level. Relative abundance of most of the identified species were affected only by time post-hatch and only the relative abundance of a single species Lactobacillus salivarius was higher ( P < 0.05) in FG compared to ACRB birds. Predicted metabolic pathways related to biosynthesis of nucleotides and biotin, especially in the cecum, were increased in SG lines. Conclusion: These results indicate that selection for growth has affected intestinal microbiota as bacterial diversity was different in the ileum and cecum which could partly explain growth rate differences among heritage and modern lines. In addition, the increased predicted metabolic pathways in the ileum of SG birds could positively affect growth rate, and further research is needed to elucidate this hypothesis.