Enterocyte dynamics and mucosal development in the posthatch chick

In vitro investigations on interference of selected probiotic candidates with Campylobacter jejuni adhesion and invasion of primary chicken derived cecal and Caco-2 cells

BACKGROUND

Campylobacter (C.) jejuni is one of the most important bacterial foodborne pathogens worldwide. Probiotics such as Lactobacillus or Bacillus species are considered one option for reducing the colonization rate and magnitude in poultry, the most frequent source of human infections. Due to the lack of suitable avian in vitro models such as chicken intestinal cell lines, especially those derived from the cecum, most in vitro studies on C. jejuni host interaction have been conducted with human intestinal cell lines. In this study, we compared C. jejuni-cell interactions between primary chicken cecal cells and the human intestinal cell line Caco-2, which is derived from colorectal adenocarcinoma, and investigated possible interfering effects of selected probiotic candidates.

RESULTS

We detected differences in adhesion and invasion between the two tested gut cell types and between different C. jejuni strains. The probiotic inhibition of C. jejuni adhesion and invasion of human and avian gut cells was affected by host cell type, investigated C. jejuni strain and time points of probiotic treatment. Additionally, our results suggest a possible correlation between C. jejuni invasion and the detected increase in IL-6 mRNA expression.

CONCLUSIONS

Our results indicate distinct differences between avian and human gut cells in their interaction with C. jejuni. Therefore, data obtained in one host species on C. jejuni-host interaction may not easily be transferrable to another one. The factors influencing the variable efficacy of probiotic intervention in chicken and human derived cells should be investigated further.

Morphological features of the late-embryo-stage gastrointestinal tract of free-roaming light ecotype Nigerian indigenous chicken

Morphological changes in the late-embryo-stage gastrointestinal tract of Nigerian indigenous chicken were investigated using anatomical techniques. The paraffin-embedded sections were stained with haematoxylin and eosin and periodic acid Schiff-Alcian blue (pH 2.5) stains. During the late pre-hatch period, the framework of the stomach was already established, but glands were yet poorly developed. Randomly oriented pre-glandular cells in the lamina propria mucosae at embryonic day (ED) 14 became organized into elongated simple tubular glands at ED 19 and assumed adult morphology at post-hatch day (PD) 1. Acidic and neutral mucin deposits were associated with the glandular cells. In the small intestine, enterocytes of the tunica epithelialis mucosae transformed from cuboidal-shaped cells (at ED 14) to tall columnar cells (at PD 1). Short crypts of Lieberkühn, goblet cells, microfold cells and enteroendocrine cells were evident at ED 19, while the lamina propria mucosae and submucosa contained mesenchymal cells, reticular cells and isolated lymphoblasts. Similarly, the crypts, lymphoblasts, mesenchymal and reticular cells were also associated with the lamina propria mucosae and submucosa of the caecum and colorectum at ED 19. It was inferred from these findings that extensive cellular and tissue modifications occur in the gastrointestinal tract within the narrow window of the late pre-hatch period. The definitive gut tunics, epithelium, glandular tissues, immune-competent cells and tissues are formed as a result. Thus, the embryonic gut of the bird is made capable of assuming its necessary functions of food digestion, nutrient absorption, water and ion re-absorption, immune surveillance, antibody production and immune responses at hatch.

Effect of in ovo injection of DL-methionine on hatchability, embryo mortality, hatching weight, blood biochemical parameters and gastrointestinal tract development of breeder chicks

The current investigation was conducted to test the potential effects of in ovo feeding of DL-methionine (MET) on hatchability, embryonic mortality, hatching weight, blood biochemical parameters and development of heart and gastrointestinal (GIT) of breeder chick embryos. 224 Rhode Island Red fertile eggs were randomly distributed into seven experimental treatments: untreated egg (control), buffered saline (0.5% NaCl), and five solutions containing increased levels of MET (0.5, 1.0, 1.5, 2.0 and 2.5%) + 0.5% NaCl, being separated into four groups/replicates (each one with 8 eggs), totaling 32 eggs/treatment. All embryos submitted to in ovo injection with MET presented a decrease in the hatchability results and an increase in the results of intermediary embryonic mortality. Chicks hatched from eggs injected with until to 1.0% MET were heavier and presented better development of the heart and GIT, especially important organs and regions for digestion and nutrient absorption. Conclusively, the in ovo feeding using MET showed positive impacts on hatching weight and GIT development of breeder chicks. However, caused negative impacts on hatchability when used at high levels.

Tff3 Deficiency Differentially Affects the Morphology of Male and Female Intestines in a Long-Term High-Fat-Diet-Fed Mouse Model

Trefoil factor family protein 3 (Tff3) protects the gastrointestinal mucosa and has a complex mode of action in different tissues. Here, we aimed to determine the effect of Tff3 deficiency on intestinal tissues in a long-term high-fat-diet (HFD)-fed model. A novel congenic strain without additional metabolically relevant mutations (Tff3-/-/C57Bl6NCrl strain, male and female) was used. Wild type (Wt) and Tff3-deficient mice of both sexes were fed a HFD for 36 weeks. Long-term feeding of a HFD induces different effects on the intestinal structure of Tff3-deficient male and female mice. For the first time, we found sex-specific differences in duodenal morphology. HFD feeding reduced microvilli height in Tff3-deficient females compared to that in Wt females, suggesting a possible effect on microvillar actin filament dynamics. These changes could not be attributed to genes involved in ER and oxidative stress, apoptosis, or inflammation. Tff3-deficient males exhibited a reduced cecal crypt depth compared to that of Wt males, but this was not the case in females. Microbiome-related short-chain fatty acid content was not affected by Tff3 deficiency in HFD-fed male or female mice. Sex-related differences due to Tff3 deficiency imply the need to consider both sexes in future studies on the role of Tff in intestinal function.

Effects of the in ovo injection of an Escherichia coli vaccine on the hatchability and quality characteristics of commercial layer hatchlings

In the commercial egg industry, avian pathogenic Escherichia coli (APEC) can lead to significant economic loss. The Poulvac E. coli vaccine (PECV) is a commercially available attenuated live vaccine commonly applied via spray or drinking water to protect against losses associated with colibacillosis. The PECV has not been tested in layer hatching eggs using in ovo injection. Therefore, the purpose of this experiment was to determine the effects of injecting 50 μL of different doses of the PECV into Hy-Line W-36-layer hatching eggs on the hatchability and quality characteristics of hatchlings. At 18 d of incubation (DOI), treatments included 1 noninjected and 1 diluent-injected control. Furthermore, PECV treatments included a full dose (4.4 × 108E. coli CFU) or serial dilutions of the full dose to produce 4.4 × 106, 4.4 × 104, or 4.4 × 102 CFU doses of E. coli. In ovo injections targeted the amnion. Percent hatchability of live embryonated eggs (HI), percent residue eggs, hatchling mortality, and female chick whole and yolk-free BW, relative yolk sac weight, and body length were among the variables examined. Treatment significantly (P < 0.0001) affected HI, with HI being highest in the control groups (97.3% in the noninjected and 94.2% in the diluent-injected), and with HI values being 89.0, 88.9, 84.4, and 71.2% in the 4.4 × 102, 4.4 × 104, 4.4 × 106, and 4.4 × 108 CFU E. coli dose treatments, respectively. The percentage of live embryos that did not complete hatch but that pipped internally (P = 0.024) or externally (P < 0.0001) were significantly affected by treatment, with percentages being highest in the 4.4 × 108 CFU treatment. Female chick body length was significantly (P < 0.0001) affected by treatment and was longer in both control groups and in the 1 × 102 CFU E. coli treatment in comparison to all other treatments. Yolk-free female chick BW was significantly (P = 0.034) affected by treatment and was lower in the 4.4 × 106 CFU and 4.4 × 108 CFU treatments when compared to the diluent-injected control group. An increase in the E. coli concentration administered in the amnion of embryonated layer hatching eggs at 18 DOI decreased hatch success and female chick yolk-free BW and body length.

Organic Acid-Based Chelate Trace Mineral Supplement Improves Broiler Performance, Bone Composition, Immune Responses, and Blood Parameters

Organic acid-based trace minerals are known to have more bioavailability, possibly due to fewer antagonism reactions in the lumen. A 42-day study was conducted to assess the supplementation of manganese (Mn), zinc (Zn), selenium (Se), iron (Fe), and copper (Cu) from different sources. To that end, a total of 1248-day-old As-hatched Arbor Acres chickens were examined for performance, histology, bone integrity, and plasma biochemical parameters. Experimental groups were as follows: basal diet supplying 50, 75, 100, and 120% of trace mineral requirements using an inorganic trace mineral supplement (ITM50, ITM75, ITM100, ITM120); basal diet supplying 33, 66, and 100% of trace mineral requirements using an organic acid-based trace mineral supplement (OAT33, OAT66, OAT100); plus a basal diet supplying 100% of trace mineral requirements using an amino acid-based chelated trace mineral supplement (ATM100%) as control positive. According to results, birds' fed OAT66 had the highest (P < 0.05) average daily body weight gain (ADG), average daily feed intake (ADFI), and lower feed conversion ratio (FCR). Feeding OAT66 increased (P < 0.05) villus length to crypt depth ratio, compared to OAT33 and ITM100 by 26% and 19%, respectively. The relative weight of the bursa enhanced by 22% in birds' receiving OAT supplement, compared to those received ITM supplement (P < 0.05). The plasma uric acid was reduced by 42% (P < 0.001) in birds fed with OAT66 and OAT100 when compared to those fed ITM50. Overall, our results indicated that the same performance could be achieved by using lower levels of organic trace minerals.

Ameliorative avian gut environment and bird productivity through the application of safe antibiotics alternatives: a comprehensive review

The avian digestive tract is an important system for converting ingested food into the nutrients their bodies need for maintenance, growth, and reproduction (meat, table eggs, and fertile eggs). Therefore, preserving digestive system integrity is crucial to bird health and productivity. As an alternative to antibiotics, the world has recently turned to the use of natural products to enhance avian development, intestinal health, and production. Therefore, the primary goal of this review is to explain the various characteristics of the avian digestive tract and how to enhance its performance with natural, safe feed additives such as exogenous enzymes, organic acids, photogenic products, amino acids, prebiotics, probiotics, synbiotics, and herbal extracts. In conclusion, the composition of the gut microbiome can be influenced by a number of circumstances, and this has important consequences for the health and productivity of birds. To better understand the connection between pathogens, the variety of therapies available, and the microbiome of the gut, additional research needs to be carried out.

Embryonic injection of Lactobacillus plantarum PA01 alters the microbial diversity in the gastrointestinal tract of the broilers before and after hatching

The total number of intestinal microbiotas is low, and the intestinal tract develops rapidly and imperfectly at the embryonic stage. Embryonic period as a particular physiological stage is an important time window to explore how to regulate organismal health by probiotics. Therefore, this experiment was conducted to investigate the effect of embryonic injection of Lactobacillus plantarum PA01 at embryonic d 14 (E14) on the microbiome of the contents of the gizzard, cecum at embryonic d 20 (E20) and cecum at d 1 posthatch (D1) by 16S rRNA sequencing. Results showed that PA01 had no significant effect on broiler body weight and yolk sac weight at E20 and D1 (P > 0.05). PA-01 altered the Shannon index and β diversity of the gizzard at E20 (P < 0.05), increased the abundance of Firmicutes (P < 0.05), and decreased the relative abundance of Proteobacteria, Bacteroidota, and Actinobacteriota (P < 0.05). At the genus level of the microbiota, PA01 significantly increased the relative abundance of Lactiplantibacillus (P < 0.05). At 20 embryos, PA01 altered the α and β diversity indices (P < 0.05) and decreased the relative abundance of Salmonella (P < 0.05) of the cecal microbiota. The biomarkers of PA01 group were Lactobacillales, Blautia, Lachnospiraceae, and Asinibacterium. Embryonic injection of PA01 altered the E20 intestinal microbes. PA01 altered the β-diversity index of the 1-day-old cecum (P < 0.05), and there was no significant effect on microbial composition at the phylum and genus level (P > 0.05). LefSe analysis revealed that the biomarkers of the PA01 group were Lactobacillaceae, Lactiplantibacillus, Moraxellaceae, and Acinetobacter. Biomarkers in the Con group were Devosia, Bacillus, Nordella, Mesorhizobium, and Pseudolabrys. PA01 increased acetic acid in the gastrointestinal tract at E20 along with acetic and butyric acid in cecum of 1-day-old. In conclusion, embryo-injected L. plantarum PA01 altered the structure and metabolites of the microbial flora before and after hatching, in particular promoting the colonization of Lactobacillus.

Impacts of Dietary Lysine and Crude Protein on Performance, Hepatic and Renal Functions, Biochemical Parameters, and Histomorphology of Small Intestine, Liver, and Kidney in Broiler Chickens

The present study aimed to investigate the effects of increasing dietary lysine (Lys) levels with an adequate dietary crude protein (CP) content, as well as the effects of a reduction in dietary CP content with the recommended amino acid (AAs) level, on the performance, blood biochemical parameters, and histomorphology of the duodenum, liver, and kidney in broiler chickens. A total of 500 broiler chickens were randomly distributed into five dietary treatment groups, following a completely randomized design, where, at the beginning, the control group (C) was fed a diet containing the standard CP and Lys levels: 23% CP with 1.44% Lys during the starter period; 21.5% CP with 1.29% Lys during the growing period; and 19.5% CP with 1.16% Lys during the finishing period. The Lys content was increased by 10% above the recommended control basal requirements in the second group (Gr1) and by 20% in the third group (Gr2), while using the same recommended CP percentage as the C group. The fourth group (Gr3) had a 1% lower CP content and the fifth group had a 2% lower CP content than the C group, with the same recommended AA level as the C group. Increasing the Lys content in the Gr1 group improved the broilers' weight gains (p < 0.05) during the starter, growing, and finishing periods. Decreasing dietary CP with the standard AA levels (Gr3 and Gr4) did not significantly affect (p > 0.05) the live weight gain, feed intake, or feed conversion ratio (FCR) of the broilers compared with those fed with the C diet. Blood total bilirubin, direct and indirect bilirubin, triglycerides, cholesterol, low-density lipoprotein (LDL), and very LDL were not different among the experimental groups. However, blood aspartate aminotransferase levels were increased (p < 0.05) in the Gr1 and Gr3 groups compared with the other treatment groups. All dietary treatments decreased the serum creatinine levels (p < 0.05) compared with the C group. The Gr2 broilers had greater serum total protein and globulin (p < 0.05) than those receiving the other treatments. Increasing dietary Lys levels resulted in a significant improvement in duodenum villus height and width (p < 0.05), while the low-CP diets resulted in shorter villi length and width, along with degenerated areas and lymphocytic infiltration. Low dietary CP content induced hepatocyte disorganization and moderate degeneration, along with vacuolated hepatic cells, excessive connective tissue, and lymphocytic infiltration. The cortical regions of the kidney exhibited obvious alterations in the Gr3 and Gr4 groups and large interstitial spaces were found between tubules. Renal tubules in the Gr3 and Gr4 groups were smaller in size and some of these tubules were atrophied. In conclusion, reducing dietary CP levels to 1% or 2% lower than the recommended level did not negatively affect growth performance, inducing minimal influence on the blood metabolic indicators of health status, and resulting in moderate alterations to the histomorphology of the duodenum, liver, and kidney. Furthermore, increasing the Lys content by 10% above the recommended level improved the growth performance, health status, and histomorphology of the duodenum, liver, and kidney in broiler chickens.

Profiling intestinal stem and proliferative cells in the small intestine of broiler chickens via in situ hybridization during the peri-hatch period

Mature small intestines have crypts populated by stem cells which produce replacement cells to maintain the absorptive villus surface area. The embryonic crypt is rudimentary and cells along the villi are capable of proliferation. By 7 d post-hatch the crypts are developed and are the primary sites of proliferation. Research characterizing the proliferative expansion of the small intestine during the peri-hatch period is lacking. The objective of this study was to profile the changes of genes that are markers of stem cells and proliferation: Olfactomedin 4 (Olfm4), Leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5), and marker of proliferation Ki67 from embryonic day 17 to 7 d post-hatch using quantitative PCR and in situ hybridization (ISH). The expression of the stem cell marker genes differed. Olfm4 mRNA increased while Lgr5 mRNA decreased post-hatch. Ki67 mRNA decreased post-hatch in the duodenum and was generally the greatest in the ileum. The ISH was consistent with the quantitative PCR results. Olfm4 mRNA was only seen in the crypts and increased with morphological development of the crypts. In contrast Lgr5 mRNA was expressed in the crypt and the villi in the embryonic periods but became restricted to the intestinal crypt during the post-hatch period. Ki67 mRNA was expressed throughout the intestine pre-hatch, but then expression became restricted to the crypt and the center of the villi. The ontogeny of Olfm4, Lgr5, and Ki67 expressing cells show that proliferation in the peri-hatch intestine changes from along the entire villi to being restricted within the crypts.

Temporal transcriptome profiling of floating apical out chicken enteroids suggest stability and reproducibility

Enteroids are miniature self-organising three-dimensional (3D) tissue cultures which replicate much of the complexity of the intestinal epithelium. We recently developed an apical-out leukocyte-containing chicken enteroid model providing a novel physiologically relevant in vitro tool to explore host-pathogen interactions in the avian gut. However, the replicate consistency and culture stability have not yet been fully explored at the transcript level. In addition, causes for the inability to passage apical-out enteroids were not determined. Here we report the transcriptional profiling of chicken embryonic intestinal villi and chicken enteroid cultures using bulk RNA-seq. Comparison of the transcriptomes of biological and technical replicate enteroid cultures confirmed their high level of reproducibility. Detailed analysis of cell subpopulation and function markers revealed that the mature enteroids differentiate from late embryonic intestinal villi to recapitulate many digestive, immune and gut-barrier functions present in the avian intestine. These transcriptomic results demonstrate that the chicken enteroid cultures are highly reproducible, and within the first week of culture they morphologically mature to appear similar to the in vivo intestine, therefore representing a physiologically-relevant in vitro model of the chicken intestine.

Potential Probiotics Role in Excluding Antibiotic Resistance

Background. Antibiotic supplementation in feed has been continued for the previous 60 years as therapeutic use. They can improve the growth performance and feed efficiency in the chicken flock. A favorable production scenario could favor intestinal microbiota interacting with antibiotic growth promoters and alter the gut bacterial composition. Antibiotic growth promoters did not show any beneficial effect on intestinal microbes. Scope and Approach. Suitable and direct influence of growth promoters are owed to antimicrobial activities that reduce the conflict between host and intestinal microbes. Unnecessary use of antibiotics leads to resistance in microbes, and moreover, the genes can relocate to microbes including Campylobacter and Salmonella, resulting in a great risk of food poisoning. Key Findings and Conclusions. This is a reason to find alternative dietary supplements that can facilitate production, growth performance, favorable pH, and modulate gut microbial function. Therefore, this review focus on different nutritional components and immune genes used in the poultry industry to replace antibiotics, their influence on the intestinal microbiota, and how to facilitate intestinal immunity to overcome antibiotic resistance in chicken.

Supplementing the early diet of broilers with soy protein concentrate can improve intestinal development and enhance short-chain fatty acid-producing microbes and short-chain fatty acids, especially butyric acid

Background

Research on nutrition in early-life commonly focuses on the maturation of the intestine because the intestinal system is crucial for ensuring continued growth. To explore the importance of early nutrition regulation in animals, soy protein concentrate (SPC) was added to the early diet of broilers to investigate its effects on amino acid digestibility, intestinal development, especially intestinal microorganisms, and broiler metabolites. A total of 192 one-day-old Arbor Acres (AA) male broilers were randomly assigned to two experimental treatments with 8 replicates of 12 birds. The control group was fed a basal diet (control), and the treatment group was fed a basal diet supplemented with 12% SPC (SPC12) during the first 10 d (starter phase). From d 11 to 21 (grower phase) and d 22 to 42 (finisher phase), a basal diet was fed to both treatment groups.

Results

SPC reduced the pH value and acid-binding capacity of the starter diet (P < 0.05, d 10); SPC in the early diet enhanced the gizzard weight (P < 0.05, d 10 and d 42) and the ileum weight (P < 0.05, d 10) and decreased the weight and length of the jejunum (P < 0.05, d 10) and the relative length of the duodenum and jejunum (P < 0.05, d 10). At the same time, SPC enhanced villus height (P < 0.05, d 10) and muscle thickness in the jejunum and ileum (P < 0.05, d 10) and increased the number of goblet cells in the duodenum (P < 0.05, d 10). Meanwhile, SPC increased the Chao1 index and the ACE index (P < 0.05, d 10) and altered the composition of caecal microflora at d 10. SPC also increased the relative abundance of Alistipes, Anaerotruncus, Erysipelatoclostridium, Intestinimonas and Flavonifractor bacteria (P < 0.05, d 10). At the same time, the concentrations of caecal butyric acid and total short-chain fatty acids (SCFAs) were also increased in the SPC12 group (P < 0.05, d 10).

Conclusions

In summary, the results showed that supplementing the starter diet of broilers with SPC has a significant effect on the early development of the intestine and the microflora.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40104-022-00749-5.

Efficacy of Various Feed Additives on Performance, Nutrient Digestibility, Bone Quality, Blood Constituents, and Phosphorus Absorption and Utilization of Broiler Chickens Fed Low Phosphorus Diet

The present trial was designed to assess the effect of phytase, multi-strain probiotic, Saccharomyces cerevisiae, and fumaric acid on performance, nutrient digestibility, bone physical parameters and mineralization, blood constituents, bone and gut histomorphology, and duodenal phosphorus transporter genes of broiler chickens fed a decreased non-phytate phosphorus (nPP) diet for 5 weeks. A total of 480 broiler chickens were allotted to six dietary groups and eight replicates each: (1) positive control diet with recommended levels of nPP (PC; 0.48, 0.44, and 0.41% in the three feeding phases); (2) negative control diet with a decreased dietary nPP (NC; 0.28, 0.24, and 0.21% in the three feeding phases); (3) NC + 600 FTU/kg phytase (PHY); (4) NC + 0.05% multi-strain probiotic (PRO); (5) NC + 0.2% Saccharomyces cerevisiae (SC); and (6) NC + 0.2% fumaric acid. Growth performance data were recorded weekly, and blood sampling was performed at days 21 and 35 of age. Bone quality traits, gut and tibia histology, nutrient digestibility, and intestinal gene expression analyses were conducted at the end of the trial (35 days of age). Final body weight and total gain at day 35 of age of the broiler chickens fed with the PHY, PRO, and SC diets were greater (p < 0.01) than in NC, where broilers fed with the PRO and PHY diets had higher values and were similar to that of PC. There was a non-significant variation in the cumulative feed intake among the treatment groups. The PHY and PRO groups had better FCR than the PC group (p < 0.05), and FA and SC had an FCR equivalent to that of PC. The PHY and PRO broilers had greater dressing % than the NC group (p < 0.05) and even better than PC. The PHY, PRO, SC, and FA broilers had higher relative weights of spleen and bursa of Fabricius (p < 0.01) than NC. In comparison to NC, the PHY, PRO, and SC groups improved (p < 0.05) CP, CF, Ca, and P digestibility. Greater tibia breaking strength of the low nPP-supplemented groups was shown to be associated with higher tibia ash, Ca, and P concentrations (p < 0.01) and increased (p < 0.001) tibia cortical area thickness. At days 21 and 35 of age, the dietary supplements to low nPP diets reduced (p < 0.05) serum total cholesterol, triglyceride, triiodothyronine, thyroxine, glucose, and alkaline phosphatase levels, while serum Ca and P concentrations were improved (p < 0.05) compared to NC. All supplements led to enhancement (p < 0.01) in villi height and width and villi absorptive surface area when compared with NC and were even comparable to that of PC. The mRNA expression of NaP-IIb was up-regulated (p < 0.001) in the duodenum of PRO and FA broilers at day 35 of age compared with NC, and their expression levels were similar to that of PC, indicating greater P availability. It is concluded that dietary supplementation of PHY, PRO, SC, and FA to a low nPP diet was advantageous and mitigated the negative impacts of P reduction on the growth performance, health, nutrient digestibility, and bone quality of broilers.

Dietary Protein Source and Litter Condition Alter Broiler Chicken Intestinal Macrophage and Mitotically Active Cell Populations

As antibiotic-free (ABF) broiler production continues to increase, understanding the development and local immune response in the intestines of ABF broilers is essential. Mitotically active cells, the majority of which will become enterocytes, help maintain the intestinal epithelial barrier. Macrophages prevent pathogen invasion by their phagocytic activity, functioning as immune response amplifying cells to aid in the recruitment of additional immune cells, and stimulating cytokine production in other adjacent cells. The objective of this experiment was to evaluate commonly used practical production practices on intestinal cell mitotic activity and local intestinal immunological responses. A randomized complete block design experiment with a 3 × 2 factorial treatment structure was conducted. The 3 dietary protein sources were: soybean meal (SBM), a mix of 50% poultry by-product meal and 50% feather meal (PFM), and porcine meat and bone meal (MBM) and broilers were reared on either new litter (NL) or used litter (UL). On d 3, 8, 11, 15, and 21, 6 birds per treatment from 6 blocks (total n = 36 per d) were randomly selected for sampling. Broilers were injected intraperitoneally with 5'-bromo-2'-deoxyuridine (BrdU) 1 h prior to sampling to label mitotically active cells. Samples were analyzed using cryohistology and immunofluorescence to determine the density of mitotically active cells and macrophages. Mitotically active cell and macrophage densities changed in both the duodenum and ileum over time. Neither dietary protein source nor litter condition affected mitotically active cell or macrophage densities in the duodenum on d 11 and 21 or in the ileum on d 3, 8, 11, and 15. However, on d 3 and 15 in the duodenum (P ≤ 0.0126) and d 21 in the ileum (P ≤ 0.0009), broilers reared on UL had greater mitotically active cell densities than those reared on NL. On d 8 in the duodenum, broilers fed MBM had increased macrophage density compared with those fed PFM and SBM (P ≤ 0.0401). These results indicate dietary protein source and litter condition may impact the physiology of the broiler small intestine, though additional work with this model is necessary to understand the underlying mechanisms.

Nutritional stimulation by in-ovo feeding modulates cellular proliferation and differentiation in the small intestinal epithelium of chicks

Nutritional stimulation of the developing small intestine of chick embryos can be conducted by in-ovo feeding (IOF). We hypothesized that IOF of glutamine and leucine can enhance small intestinal development by promoting proliferation and differentiation of multipotent small intestinal epithelial cells. Broiler embryos (n = 128) were subject to IOF of glutamine (IOF-Gln), leucine (IOF-Leu), NaCl (IOF-NaCl) or no injection (control) at embryonic d 17 (E 17). Multipotent, progenitor and differentiated cells were located and quantified in the small intestinal epithelium between E 17 and d 7 after hatch (D 7) in all treatment groups by immunofluorescence of SRY-box transcription factor 9 (Sox9) and proliferating cell nuclear antigen (PCNA), in-situ hybridization of leucine-rich repeat containing G-protein coupled receptor 5 (Lgr5) and peptide transporter 1 (PepT1) and histochemical goblet cell staining. The effects of IOF treatments at E 19 (48 h post-IOF), in comparison to control embryos, were as follows: total cell counts increased by 40%, 33% and 19%, and multipotent cell counts increased by 52%, 50% and 38%, in IOF-Gln, IOF-Leu and IOF-NaCl embryos, respectively. Only IOF-Gln embryos exhibited a significance, 36% increase in progenitor cell counts. All IOF treatments shifted Lgr5+ stem cell localizations to villus bottoms. The differentiated, PepT1+ region of the villi was 1.9 and 1.3-fold longer in IOF-Gln and IOF-Leu embryos, respectively, while goblet cell densities decreased by 20% in IOF-Gln embryos. Post–hatch, crypt and villi epithelial cell counts were significantly higher IOF-Gln chicks, compared to control chicks (P < 0.05). We conclude IOF of glutamine stimulates small intestinal maturation and functionality during the peri-hatch period by promoting multipotent cell proliferation and differentiation, resulting in enhanced compartmentalization of multipotent and differentiated cell niches and expansions of the absorptive surface area.

Role of Physiology, Immunity, Microbiota, and Infectious Diseases in the Gut Health of Poultry

“Gut health” refers to the physical state and physiological function of the gastrointestinal tract and in the livestock system; this topic is often focused on the complex interacting components of the intestinal system that influence animal growth performance and host-microbial homeostasis. Regardless, there is an increasing need to better understand the complexity of the intestinal system and the various factors that influence gut health, since the intestine is the largest immune and neuroendocrine organ that interacts with the most complex microbiome population. As we face the post-antibiotic growth promoters (AGP) era in many countries of the world, livestock need more options to deal with food security, food safety, and antibiotic resilience to maintain agricultural sustainability to feed the increasing human population. Furthermore, developing novel antibiotic alternative strategies needs a comprehensive understanding of how this complex system maintains homeostasis as we face unpredictable changes in external factors like antibiotic-resistant microbes, farming practices, climate changes, and consumers’ preferences for food. In this review, we attempt to assemble and summarize all the relevant information on chicken gut health to provide deeper insights into various aspects of gut health. Due to the broad and complex nature of the concept of “gut health”, we have highlighted the most pertinent factors related to the field performance of broiler chickens.

Induction of gut leakage in young broiler chickens fed a diet with low rye inclusion

The aim of the present study was to assess the absence of a non-starch polysaccharide (NSP) enzyme in a broiler diet containing a low level (10%) of rye inclusion. Two experimental groups with 40 Ross broilers each, were fed a diet containing 10% rye. One group was supplemented with a NSP enzyme, and the other was not supplemented with the enzyme to increase intestinal viscosity. The birds were fed the respective diets for 14 or 28 days. Intestinal sections were submitted to morphological, morphometric and mRNA-level gene expression analyses. To assess gut leakage, 150 min before euthanasia, broilers had no access to feed and received an oral gavage with fluorescein isothiocyanate-labelled dextran (FITC-d). Serum levels of FITC-d, D-lactate, tight-junction-associated protein 1 (TJAP1), citrulline and ovotransferrin were determined. A significant increase in FITC-d levels was observed in the 14-day-old birds fed the non-supplemented rye diet, and no other serum markers were affected. These birds presented a decreased villus height/crypt depth (VH:CD) ratio and an increased degree of damage in the jejunum. The ileum VH:CD increased, and the goblet cell number decreased in 28-day-old birds fed the non-supplemented rye diet. When broilers were fed the non-supplemented rye diet, the mRNA expression of the tight-junction zona occludens 1 (ZO1) was significantly decreased in the jejunum of 14-day-old broilers, whereas a significant decrease in jejunum mRNA expression of ZO2 and mucin-2 (MUC2) was observed in the jejunum of 28-day-old broilers. In contrast, a significant increase in the mRNA expression of ZO2 was observed in the ileum from 28-day-old broilers fed the non-supplemented rye diet. In conclusion, a 10% rye diet causes intestinal stress in young broiler chickens when the feed is not supplemented with a NSP enzyme. This study may be applied as experimental model of mild gut leakage of broiler chickens.

Light and transmission electron microscopic evaluation of the lamina epithelialis mucosae in the ileum of pre- and post-hatch broiler chicken

Morphological development of the lamina epithelialis mucosae (LEM) of the ileum of broiler chicken was evaluated using light and transmission electron microscopic techniques. Ileal sections were collected on embryonic days (ED) 14, 17 and 19, as well as post-hatch days (PD) 1, 3, 5, 7, 14, 21, 28, 35, 42 and 56. The result showed that the ileal LEM, which were poorly defined at embryonic days 14 and 17, consisted of enterocytes and some atypically shaped goblet cells. Apico-lateral tight junctions and irregularly shaped microvilli were associated with the enterocytes at ED 14 and 17. The enterocyte microvilli were more uniform in shape and distribution at ED 19. The embryonic goblet cells were varied in shape and possessed basally displaced, star-shaped nuclei and small apical cytoplasmic vacuoles. During the post-hatch ages, the LEM was a typical epithelium with a single layer of columnar-shaped enterocytes that became highly elongated at post-hatch day (PD) 7. The goblet cells were characteristically 'wine-glass' shaped. Follicle-associated epithelium (FAE) showing numerous lymphocytes among the enterocytes occurred in the post-hatch LEM. The intra-epithelial lymphocytes (IEL) were first encountered at PD 1, but increased several folds within the first two weeks post-hatch. Entero-endocrine cells were observed in the epithelium from PD 21. Finally, from this study, it is obvious that enterocytes and small atypically shaped goblet cells occur in the ileal LEM during the pre-hatch period, but these cells assume adult morphological characteristics after hatch. Thus, the cells of the ileal LEM play strategic absorptive, secretory and protective roles in the gut.

Managing Gut Microbiota through In Ovo Nutrition Influences Early-Life Programming in Broiler Chickens

The chicken gut is the habitat to trillions of microorganisms that affect physiological functions and immune status through metabolic activities and host interaction. Gut microbiota research previously focused on inflammation; however, it is now clear that these microbial communities play an essential role in maintaining normal homeostatic conditions by regulating the immune system. In addition, the microbiota helps reduce and prevent pathogen colonization of the gut via the mechanism of competitive exclusion and the synthesis of bactericidal molecules. Under commercial conditions, newly hatched chicks have access to feed after 36-72 h of hatching due to the hatch window and routine hatchery practices. This delay adversely affects the potential inoculation of the healthy microbiota and impairs the development and maturation of muscle, the immune system, and the gastrointestinal tract (GIT). Modulating the gut microbiota has been proposed as a potential strategy for improving host health and productivity and avoiding undesirable effects on gut health and the immune system. Using early-life programming via in ovo stimulation with probiotics and prebiotics, it may be possible to avoid selected metabolic disorders, poor immunity, and pathogen resistance, which the broiler industry now faces due to commercial hatching and selection pressures imposed by an increasingly demanding market.

Effects of aflatoxin B1 and monensin interaction on liver and intestine of poultry – influence of a biological additive (Pichia kudriavzevii RC001)

The aim of this study was to evaluate the effects of aflatoxin B1 (AFB1) and monensin (MONS) interaction on the liver and intestinal histological changes in poultry, and the influence of Pichia kudriavzevii RC001. One-day-old commercial line (Ross 308) broilers (n=120) were individually weighed and randomly assigned to 8 treatments (15 broilers/treatment, 5 broilers per cage and 3 replicates/treatment). The experimental diets were: Group 1: basal diet (BD); Group 2: BD + MONS (50 mg/kg); Group 3: BD + P. kudriavzevii RC001 (1 g/kg); Group 4: BD + AFB1 (100 μg/kg); Group 5: BD + MONS + P. kudriavzevii RC001; Group 6: BD + AFB1 + P. kudriavzevii RC001; Group 7: BD + AFB1 + MONS + P. kudriavzevii RC001; Group 8: BD + AFB1 + MONS. When MONS was added, the typical AFB1 macroscopic and microscopic alterations were intensified. The P. kudriavzevii RC001 cytotoxicity and genotoxicity assays with Vero cells and with broiler chicken’s erythrocytes, demonstrated that P. kudriavzevii RC001 neither were non-cytotoxic nor genotoxic. When MONS was added in the presence of P. kudriavzevii RC001, the toxic effect of AFB1 on liver was not prevented. When P. kudriavzevii was present alone, the same prevention of the pathological damage was observed in the intestine of poultry fed with AFB1. The smallest apparent absorption area was obtained when AFB1 and MONS were added in the feed (P<0.05). AFB1 and MONS interaction demonstrated important toxic effects. Although P. kudriavzevii was effective in ameliorating the adverse effects of AFB1 alone on liver pathology and gut morphology, it was not able to diminish the toxic effects of AFB1 in presence of MONS. It suggests that P. kudriavzevii could be used as feed additive or counteracting the toxic effects of AFB1 in poultry production in the absence of MONS.

Novel chicken two-dimensional intestinal model comprising all key epithelial cell types and a mesenchymal sub-layer

The intestinal epithelium plays a variety of roles including providing an effective physical barrier and innate immune protection against infection. Two-dimensional models of the intestinal epithelium, 2D enteroids, are a valuable resource to investigate intestinal cell biology and innate immune functions and are suitable for high throughput studies of paracellular transport and epithelial integrity. We have developed a chicken 2D enteroid model that recapitulates all major differentiated cell lineages, including enterocytes, Paneth cells, Goblet cells, enteroendocrine cells and leukocytes, and self-organises into an epithelial and mesenchymal sub-layer. Functional studies demonstrated the 2D enteroids formed a tight cell layer with minimal paracellular flux and a robust epithelial integrity, which was maintained or rescued following damage. The 2D enteroids were also able to demonstrate appropriate innate immune responses following exposure to bacterial endotoxins, from Salmonella enterica serotype Typhimurium and Bacillus subtilis. Frozen 2D enteroids cells when thawed were comparable to freshly isolated cells. The chicken 2D enteroids provide a useful ex vivo model to study intestinal cell biology and innate immune function, and have potential uses in screening of nutritional supplements, pharmaceuticals, and bioactive compounds.

Development and Functional Properties of Intestinal Mucus Layer in Poultry

Intestinal mucus plays important roles in protecting the epithelial surfaces against pathogens, supporting the colonization with commensal bacteria, maintaining an appropriate environment for digestion, as well as facilitating nutrient transport from the lumen to the underlying epithelium. The mucus layer in the poultry gut is produced and preserved by mucin-secreting goblet cells that rapidly develop and mature after hatch as a response to external stimuli including environmental factors, intestinal microbiota as well as dietary factors. The ontogenetic development of goblet cells affects the mucin composition and secretion, causing an alteration in the physicochemical properties of the mucus layer. The intestinal mucus prevents the invasion of pathogens to the epithelium by its antibacterial properties (e.g. β-defensin, lysozyme, avidin and IgA) and creates a physical barrier with the ability to protect the epithelium from pathogens. Mucosal barrier is the first line of innate defense in the gastrointestinal tract. This barrier has a selective permeability that allows small particles and nutrients passing through. The structural components and functional properties of mucins have been reviewed extensively in humans and rodents, but it seems to be neglected in poultry. This review discusses the impact of age on development of goblet cells and their mucus production with relevance for the functional characteristics of mucus layer and its protective mechanism in the chicken’s intestine. Dietary factors directly and indirectly (through modification of the gut bacteria and their metabolic activities) affect goblet cell proliferation and differentiation and can be used to manipulate mucosal integrity and dynamic. However, the mode of action and mechanisms behind these effects need to be studied further. As mucins resist to digestion processes, the sloughed mucins can be utilized by bacteria in the lower part of the gut and are considered as endogenous loss of protein and energy to animal. Hydrothermal processing of poultry feed may reduce this loss by reduction in mucus shedding into the lumen. Given the significance of this loss and the lack of precise data, this matter needs to be carefully investigated in the future and the nutritional strategies reducing this loss have to be defined better.

Intestinal brush border assembly during the peri-hatch period and its contribution to surface area expansion

Microvilli generate the small intestinal brush border, the main site of nutrient digestion and absorption. Mucosal structuring of the small intestine of chicken during the perihatch period has been widely researched, yet the developmental dynamics of microvilli during this period have not been fully characterized. In this study, we examined the structural and molecular characteristics of microvilli assembly and maturation during the perihatch period. Small intestines of broiler embryos and chicks were sampled at prehatch ages 17 E and 19 E, at day of hatch (DOH) and at 1, 3, 7, and 10 d posthatch. Morphological evaluations and measurements were conducted by scanning electron microscopy (SEM) and light microscopy (LM) (n = 3/timepoint), and expression of microvilli structural genes Plastin 1, Ezrin, and Myo1a was examined by Real-Time qPCR (n = 6/timepoint). Results revealed dissimilar patterns of microvilli and villi development during the perihatch period. From 19 E to 1 d, microvilli lengths increased 4.3-fold while villi lengths increased 2.8-fold (P < 0.0001). From 3 to 7 d, villi lengths increased by 20% (P < 0.005), while microvilli lengths decreased by 41% (P = 0.001). At 10 d, microvilli lengths stabilized, while villi continued to elongate by 26% (P < 0.0001). Estimations of the microvilli amplification factor (MAF) and total enterocyte surface area (TESA) revealed similar trends, with peak values of 78.53 and 1961.67 µm², respectively, at 3 d. Microvilli structural gene expression portrayed diverse patterns. Expression of Plastin 1, which bundles and binds actin cores to the terminal web, increased 8.7-fold between 17 E and DOH (P = 0.005), and gradually increased up to 7 d (P = 0.045). Ezrin and Myo1a, both actin core-cell membrane cross-linkers, portrayed different expression patterns throughout the perihatch period, as Ezrin expression was relatively stable, while Myo1a expression increased 15.8-fold between 17 E and 10 d (P < 0.0001). We conclude that microvilli assembly during the perihatch period is a rapid, coordinated process, which dramatically expands the digestive and absorptive surface area of the small intestine before the completion of villi maturation.

Susceptibility of Broiler Chickens to Deoxynivalenol Exposure via Artificial or Natural Dietary Contamination

Simple Summary

This study evaluated the effect of diets artificially or naturally contaminated with 4000 μg/kg deoxyvalenol (DON) on the intestinal integrity and nutrient absorption of broiler chickens. Young broiler chickens (14 days old) were more sensitive to DON than older birds (28 days old), and negative impacts were observed when diets were naturally contaminated with DON. Aside from the decrease in the villus height of the jejunum in young broilers, their capacity to absorb peptides was decreased, as shown by the down-regulation of a peptide transporter. However, this effect was compensated in older broilers by an increase in the expression of carbohydrate transporter.

Abstract

Multi-mycotoxin contamination of poultry diets is a recurrent problem, even if the mycotoxins levels are below EU recommendations. Deoxynivalenol (DON) is one of the main studied mycotoxins due to its risks to animal production and health. When evaluating the effects of DON, one must consider that under practical conditions diets will not be contaminated solely with this mycotoxin. In the present study, broiler chickens were fed diets with negligible mycotoxin levels or with naturally or artificially contaminated diets containing approximately 4000 μg/kg DON. Birds were sampled at D14 and D28. Naturally-contaminated diets caused the most harm to the birds, especially the young ones, which presented decreased jejunal villus height and increased lesions, down-regulation of a peptide transporter. At D28 broiler chickens seemed to have adapted to the dietary conditions, when no differences were observed in villus morphometry, together with up-regulation of a carbohydrate transporter. However, intestinal lesions remained present in these older birds.

Inside-out chicken enteroids with leukocyte component as a model to study host-pathogen interactions

Mammalian three-dimensional (3D) enteroids mirror in vivo intestinal organisation and are powerful tools to investigate intestinal cell biology and host-pathogen interactions. We have developed complex multilobulated 3D chicken enteroids from intestinal embryonic villi and adult crypts. These avian enteroids develop optimally in suspension without the structural support required to produce mammalian enteroids, resulting in an inside-out enteroid conformation with media-facing apical brush borders. Histological and transcriptional analyses show these enteroids comprise of differentiated intestinal epithelial cells bound by cell-cell junctions, and notably, include intraepithelial leukocytes and an inner core of lamina propria leukocytes. The advantageous polarisation of these enteroids has enabled infection of the epithelial apical surface with Salmonella Typhimurium, influenza A virus and Eimeria tenella without the need for micro-injection. We have created a comprehensive model of the chicken intestine which has the potential to explore epithelial and leukocyte interactions and responses in host-pathogen, food science and pharmaceutical research.

Protective effect of dietary supplementation of Bupleurum falcatum L saikosaponins on ammonia exposure-induced ileum injury in broilers

Ammonia (NH3) at a high concentration has been recognized as a highly poisonous pollutant affecting both air and water quality. NH3, as a stimulus, exerts negative impact on broiler growth and production, but the molecular mechanisms are not clear yet. This study was designed to evaluate the effects of dietary supplementation of Bupleurum falcatum L saikosaponins (SP) on the growth and ileum health status in broilers exposed to NH3. Day-old Arbor Acers broilers (n = 480) were randomly allocated into 1 of 4 treatments. The main factors were dietary SP supplementation (0 or 80 mg/kg of diet) and NH3 challenge (with or without 70 ± 5 ppm NH3). The data of growth, intestinal morphology, and mRNA expression related to ileal function were collected from broilers exposed to NH3 for 7 d. Results showed that NH3 remarkably suppressed growth performance and intestinal development as well as induced biological injuries in the ileum of broilers, resulting from oxidative stress, mucous barrier damage, and immune dysfunction as well as upregulated apoptosis. These negative effects of NH3 were alleviated by the SP supplement. In conclusion, dietary supplementation of SP may be helpful in alleviating the detrimental effects of NH3 on the ileum development in broilers.

Interrelationship of myo-inositol pathways with systemic metabolic conditions in two strains of high-performance laying hens during their productive life span

Adaptation to metabolic challenges is an individual process in animals and human, most likely based on genetic background. To identify novel pathways of importance for individual adaptation to a metabolic challenge such as egg production in laying hens, myo-inositol (MI) metabolism and plasma metabolite profiles during the productive lifespan were examined in two genetically different strains, Lohmann Brown-Classic (LB) and LSL-Classic (LSL) hens. They were housed during the productive lifespan and sampled at 10, 16, 24, 30 and 60 weeks of age. The targeted AbsoluteIDQ p180 Kit was used for metabolite profiling in plasma whereas a MI enzymatic kit and ELISAs were used to quantify tissue MI concentrations and MI key enzymes (IMPase 1 and MIOX), respectively. As major finding, kidney MIOX was differently expressed in LB and LSL hens with higher amounts in LB. The onset of egg laying between week 16 and 24 of life span was associated with a clear change in the metabolite profiles, however LSL hens and LB hens adapt differently. Pearson's correlation analyses over all hens at all time points indicated that higher expression of MI degrading enzyme MIOX was related to markers indicating metabolic stress.

Competitive Exclusion of Intra-Genus Salmonella in Neonatal Broilers

Salmonellosis is a zoonotic infection caused by Salmonella enterica serotypes contracted from contaminated products. We hypothesized that competitive exclusion between Salmonella serotypes in neonatal broilers would reduce colonization and affect the host immune response. Day of hatch broilers were randomly allocated to one of six treatment groups: (1) control, which received saline, (2) Salmonella Kentucky (SK) only on day 1 (D1), (3) Salmonella Typhimurium (ST) or Salmonella Enteritidis (SE) only on D1, (4) SK on D1 then ST or SE on day 2 (D2), (5) ST or SE on D1 then SK on D2, and (6) SK and ST or SE concurrently on D1. Salmonella gut colonization and incidence were measured from cecal contents. Livers and spleens were combined and macerated to determine systemic translocation. Relative mRNA levels of interleukin-1β (IL-1β), IL-6, IL-10, IL-18, and gamma interferon (IFN-γ) were measured in cecal tonsils and liver to investigate local and systemic immune responses. When a serotype was administered first, it was able to significantly reduce colonization of the following serotype. Significant changes were found in mRNA expression of cytokines. These results suggest competitive exclusion by Salmonella enterica serotypes affect local and systemic immune responses.

In ovo inoculation of an Enterococcus faecium-based product to enhance broiler hatchability, live performance, and intestinal morphology

Previous studies have suggested the use of probiotics, as alternative to antibiotics, to enhance broiler performance. The administration of probiotics in feed has been widely explored; however, few studies have evaluated the in ovo inoculation of probiotics. Therefore, the objective was to evaluate the impact of in ovo inoculation of different concentrations of GalliPro Hatch (GH), an Enterococcus faecium-based probiotic, on hatchability, live performance, and gastrointestinal parameters. Ross x Ross 708 fertile eggs were incubated, and on day 18, injected with the following treatments: 1) 50 μL of Marek's vaccine (MV), 2) MV and 1.4 × 105 cfu GH/50 μL, 3) MV and 1.4 × 106 cfu GH/50 μL, 4) MV and 1.4 × 107 cfu GH/50 μL. On the day of hatch, chicks were weighed, feather sexed, and hatch residue was analyzed. Male birds (640) were randomly assigned to 40 floor pens. On day 0, 7, 14, and 21 of the grow-out phase, performance data were collected. One bird from each pen was used to obtain yolk weight and intestinal segment weight and length. Hatchability was not impacted by any GH treatment (P = 0.58). On day 0, yolk weight was lower for all treatments than for MV alone. On day 0 to 7, feed intake was lower for 105 and 107 GH; the feed conversion ratio (FCR) was lower for all treatments than for MV alone (P = 0.05; P = 0.01, respectively). From day 14 to 21, the 107 GH treatment had higher BW gain (P = 0.05). For day 0 to 21, 107 GH had a lower FCR than MV alone (P = 0.03). On day 0, all GH treatments resulted in heavier tissues and longer jejunum, ileum, and ceca lengths than MV alone (P < 0.05). Spleen weight was higher for 105 and 107 GH than for MV alone. In conclusion, GH does not impact hatchability, and some concentrations improved live performance through the first 21 d of the grow-out phase. These improvements could result from the increased yolk absorption and improved intestinal and spleen morphology seen in this study.

Effect of delayed feeding post-hatch on expression of tight junction- and gut barrier-related genes in the small intestine of broiler chickens during neonatal development

The gut not only plays a key role in digestion and absorption of nutrients but also forms a physical barrier and first line of defense between the host and the luminal environment. A functional gut barrier (mucus and epithelial cells with tight junctions [TJ]) is essential for optimal health and efficient production in poultry. In current broiler system, chicks are deprived of food and water up to 72 h due to uneven hatching, hatchery procedures, and transportation. Post-hatch feed delay results in lower BW, higher FCR and mortality, and delayed post-hatch gut development. Little is known about the effects of early neonatal development and delayed feeding immediately post-hatch on gut barrier function in chickens. Therefore, the aim of the present study was to characterize the expression pattern of gut barrier-related and TJ-related genes in the small intestine of broiler chickens during early development and delay in access to feed. Newly hatched chicks received feed and water immediately after hatch or were subjected to 48 h delayed access to feed to mimic commercial hatchery setting and operations. Birds were sampled (n = 6) at -48, 0, 4, 24, 48, 72, 96, 144, 192, 240, 288, and 336 h post-hatch. Jejunum and ileum were collected, cleaned of digesta, and snap-frozen in liquid nitrogen or fixed in paraformaldehyde. The relative mRNA levels of gut barrier- and TJ-related protein genes were measured by quantitative PCR and analyzed by 2-way ANOVA. In both tissues, changes (P < 0.05) in gene expression pattern of gut barrier-related and TJ-related genes were detected due to delayed access to feed post-hatch and/or development. In general, expression of TJ-related genes was downregulated while mRNA levels of gut barrier-related genes were upregulated during development. Histological differences and changes in mucin staining due to age and treatment were observed. These results suggest that delayed access to feed post-hatch may affect TJ structure and/or function and therefore gut barrier function and overall health of the chicken small intestine.

Effects of putrescine injection in broiler breeder eggs

The aim of this study was to evaluate the effects of increasing doses of putrescine injected in ovo on hatchability, intestinal morphology and pre-starter performance of broilers. For this purpose, 720 eggs from broiler breeders were separated into a negative control (no injection) and injection treatments with increasing doses of putrescine (0.05; 0.1; 0.15 and 0.2%), totalling five treatments of 144 eggs each. Eggs were distributed in a completely randomized design inside the setter and the injection of solutions occurred at 17 days of incubation. After hatch, 330 birds were housed in mixed lots following the original treatments, totalling 5 treatments of 6 replicates with 11 birds each. Six birds per treatment were weighed and euthanized by cervical dislocation to collect the liver, intestine and breast 24 hr after injection, at hatch and 24 hr after hatch. At 2 days of age, intestines were collected from 4 animals per treatment to analyse histomorphology. The effects of putrescine levels were evaluated by polynomial regression models, ANOVA and Tukey test at 5% probability. The hatchability decreased linearly in response to increased doses of putrescine. The percentage of residual yolk was lower in animals that received putrescine compared to the control. After injection, the percentage of breast increased linearly, and the percentage of intestine had a quadratic response to increased doses of putrescine. However, 24 hr after hatch, the percentage of intestine linearly decreased, and the percentage of liver linearly increased in response to increased doses of putrescine. Villus height increased quadratically, crypt depth decreased linearly, and goblet cells increased linearly in response to the putrescine dose. FI and BWG were not affected in the pre-starter phase; however, FCR increased in response to increased levels of putrescine. Due to putrescine effects on embryos, it is recommended that the doses injected in ovo not exceed 0.1%.

Effects of First Feed Administration on Small Intestinal Development and Plasma Hormones in Broiler Chicks

Simple Summary

In this study, the effects of first feed administration on intestinal morphology, barrier function, and plasma hormones in broilers during the initial 168 h posthatch. Results revealed that early feeding posthatch had a positive effect on small intestinal growth by increasing weight and improving intestinal morphology and barrier function. In other words, early feeding promoted intestinal development, which could be very meaningful for commercial broiler production.

Abstract

(1) Background: Under practical conditions, newly hatched chicks were usually withheld feed and water for 48 to 72 h. It was shown that early feeding after hatch promoted gastrointestinal development of broiler chicks. However, the mechanism of early feeding affecting intestinal development in chicks needs further research. The present study was conducted to investigate the effects of first feed administration on intestinal morphology, barrier function, and plasma hormones in broilers during the initial 168 h posthatch. (2) Methods: A total of 720 one-day-old chicks (newborn chick, Lingnan Yellow) were placed 2 h after hatch and randomly assigned to three treatments: Group A (feed immediately after placement), Group B (fasting for 24 h after placement), and Group C (fasting for 48 h after placement). The trial lasted for 168 h and water ad libitum all the time. Sampling was performed at 0, 24, 48, 72, 120, and 168 h. (3) Results: Higher (p < 0.05) absolute weight and relative weight of the small intestine were observed in Group A. Moreover, the villus height, crypt depth, and ratio of the jejunum and ileum were significantly higher (p < 0.05) in Groups A and B than those in Group C. Microvilli of the duodenum were closely packed in Group A but sparse and disorganized in Groups B and C. The expression levels of mRNA and protein of tight junction genes (occludin and claudin-1) were upregulated (p < 0.05) in Group A. The levels of gastrin and insulin in plasma were decreased (p < 0.05) significantly in the Groups B and C. However, chicks in Groups B and C had higher (p < 0.05) plasma glucagon levels at 24 and 48 h after placement. (4) Conclusions: These results suggested that early feeding posthatch had a positive effect on small intestinal growth increasing weight and improving intestinal morphology and barrier function.

Probiotic Bacillus amyloliquefaciens H57 ameliorates subclinical necrotic enteritis in broiler chicks by maintaining intestinal mucosal integrity and improving feed efficiency

Subclinical necrotic enteritis (NE) was induced in broiler chicks using a high dose of Eimeria spp. vaccine in the drinking water on day 9, and Clostridium perfringens (Cp) culture mixed in the feed on days 14 and 15. The aim was to evaluate the effects of probiotic Bacillus amyloliquefaciens strain H57 (H57) in preventing NE in chicks. Day-old Ross 308, male broilers were weighed and randomly assigned to 6 treatment groups (6 replicate cages/treatment and 8 birds/cage). Birds in group 1 (control) were fed the basal wheat-soybean diet without H57 or NE infection; in group 2 (Eimeria) were treated with Eimeria alone; in group 3 (Cp) were treated with Cp alone; in group 4 (NE) received both Eimeria and Cp; in group 5 (NE-H57) received NE infection and H57; and group 6 (H57) received H57. The basal diet of chicks in groups 5 and 6 was supplemented with H57 at a density of 2 × 108 spores/g feed from 1 D of age. On day 21, there were no significant treatment effects on BW and feed intake between control and H57 birds. However, on day 21, the feed conversion ratio of NE-H57 birds was significantly improved when compared with NE birds (1.28 vs. 1.36; P < 0.001). Birds challenged with NE had a higher occurrence of pasty vent than birds infected with either Eimeria, Cp, or NE-H57 (41 vs. 27 vs. 29 vs. 19%, respectively; P < 0.001). Intestinal lesion scores of NE birds were also higher than those of Eimeria, Cp, and NE-H57 birds (5.67 vs. 2.56 vs. 2.78 vs. 2.10, respectively; P < 0.001) and correlated with pasty vent (Pearson's r = 0.56; P < 0.001). Microscopic evaluation showed mucosal damage and necrosis in NE birds. In contrast, villi from NE-H57 birds were normal, with no damage or infiltration with Eimeria or Cp. H57 appears to be effective in challenged birds, as it maintained epithelial barrier integrity and improved feed efficiency.

Paternal weight of ducks may have an influence on offspring' small intestinal function and cecal microorganisms

Background

In animals, many factors affect the small intestinal function and cecal microorganisms, including body weight and genetic background. However, whether paternal weight impacts the small intestinal function and cecal microorganisms remains unknown to date. The current study used Nonghua sheldrake to estimate the effect of paternal weight on the intestine of the offspring by evaluating differences in small intestinal morphology, digestive enzyme activity, and cecal microorganisms between the offspring of male parents with high body weight (group H) and that of male parents with low body weight (group L).

Results

The results of the analysis of small intestinal morphology showed that the villus height of the jejunum of group H ducks was higher than that of group L ducks, and the difference was significant for ducks at 10 weeks of age. Moreover, the villus height/crypt depth of the duodenum in group H significantly exceeded that of group L at a duck age of 2 weeks. The amylase activity in the jejunum content of group H exceeded that of group L at 5 and 10 weeks of age. Furthermore, the proportion of the Firmicutes to Bacteroidetes was significantly higher in group H (duck age of 2 weeks). Among the genera with a relative abundance exceeding 1%, the relative abundances of genera Desulfovibrio, Megamonas, Alistipes, Faecalibacterium, and Streptococcus observed in group H were significantly different between group H and group L.

Conclusions

For the first time, this study identifies the effect of paternal weight on offspring small intestinal function and cecal microorganisms. Consequently, this lays a foundation for further research on the relationship between male parents and offspring intestinal function.

Effects of in ovo feeding of N-acetyl-L-glutamate on early intestinal development and growth performance in broiler chickens

The present study determined the effects of in ovo feeding (IOF) of N-acetyl-L-glutamate (NAG) on early intestinal development and growth performance of broilers. A total of 702 fertile broiler eggs were randomly divided into 3 treatments: 1) non-punctured control group, 2) saline-injected control group, and 3) NAG solution-injected group (1.5 mg/egg). At 17.5 D of incubation, 300 μL of each solution was injected into each egg of injected groups. Results indicated that the hatchability and healthy chicken rate were not affected by NAG injection (P > 0.05). Chicks from NAG solution-injected group had significantly decreased average daily feed intake and feed conversion ratio during 1-14 D than those in the non-punctured control group (P < 0.05). Compared with the non-punctured control group, IOF of NAG significantly increased the density of goblet cells in jejunum at hatch, duodenum at 7 D, and ileum at 14 D; decreased crypt depth in jejunum at hatch; and increased villus height in duodenum and jejunum and villus height:crypt depth ratio in duodenum at 7 D (P < 0.05). The intestinal mRNA expression of Na⁺-dependent neutral amino acid transporter, peptide transporter, and excitatory amino acid transporter 3 did not differ between groups at 7 or 14 D. However, the mRNA expression level of rBAT in jejunum significantly increased in the NAG solution-injected group than in the non-punctured control group at 7 D (P < 0.05). In conclusion, IOF of NAG (1.5 mg/egg) accelerated the early intestinal development by enhancing intestinal immune and absorption function, thereby positively affecting the feed efficiency for the first 2 wk post-hatch.

The effects of feeding yeast bioactives to broiler breeders and/or their offspring on growth performance, gut development, and immune function in broiler chickens challenged with Eimeria

Yeast bioactives (YB) may stimulate broiler breeders (BB) to increase deposition of immunoglobulins (Ig) in eggs. We investigated the effects of feeding YB (mixture of derivatives from whole yeast subjected to enzymatic hydrolysis) to BB and/or their offspring on growth performance, gut development, and immune function in broiler chickens challenged with Eimeria. The BB (Ross 708 ♀ and Ross ♂) were assigned to 2 groups (60 ♀ and 10 ♂) and fed basal or basal diet supplemented with 500 g of YB/Mt. A total of 250 fertile eggs per treatment were collected, incubated, hatched, and sexed. Additional egg samples were analyzed for IgA and IgY contents. A total of 160 broiler chicks (80 ♀ and 80 ♂) from each breeder experimental group were placed in cages based on sex and BW resulting in 32 cages for each BB treatment group. Cages (16 per BB treatment group) were allocated to basal broiler chick diet or basal diet supplemented with 500 g of YB/Mt. On day 9, half of each BB by broiler chick dietary treatments was challenged with 1 mL of Eimeria culture (100,000 oocysts of Eimeria acervulina and 25,000 oocysts of Eimeria maxima). On day 14, all birds were necropsied for intestinal lesion scores and samples. Feeding YB to BB increased (P < 0.05) IgA concentration in egg yolk. Eimeria challenge decreased (P < 0.05) pancreas weight, jejunal villus height (VH), and growth performance but increased spleen weight, intestinal mass and jejunal mucosa IgA concentration. Independent of Eimeria challenge, feeding YB to BB and/or to chicks resulted in higher (P < 0.001) jejunal VH compared with feeding it to BB only or not at all. In conclusion, Eimeria challenge reduced growth performance and had negative effects on indices of intestinal function and health. Feeding YB to BB increased deposition of IgA in hatching eggs and improved jejunal VH independent of Eimeria challenge when fed to BB and/or to broiler chicks.

Growth performance, pH value of gizzard, hepatic enzyme activity, immunologic indicators, intestinal histomorphology, and cecal microflora of broilers fed diets supplemented with processed lignocellulose

This study was performed to investigate the hypothesis that supplementation of processed lignocellulose (PL) in the diets of broilers has a positive effect on growing performance, pH value of gizzard, hepatic enzyme activity, immunologic indicators, histomorphological character of small intestine, and cecal microflora populations. A total of 720 one-day-old Ross 308 broiler chicks were allotted to 4 treatment groups and fed maize−soybean meal based diets. The basal diet was supplemented with PL with an amount of 0 kg (control), 0.5 kg, 1 kg, and 2 kg per ton feed. Growing performance parameters, were determined weekly until 35 D of age. Blood samples for enzyme activities and immunoglobulins, jejunum and cecum samples for histomorphological characters for villus growth, and microbial population were collected from 12 broilers from each group. At 35 D of age, body weight of broilers supplemented with 1 kg of PL was found to be the highest with a value of 2305.0 g, when compared to the broilers supplemented with control, 0,5 and 2 kg of PL groups (2154.0, 2201.0, and 2141.7 g, respectively, P = 0.001). An increased activity of aspartate amino transferase (AST) was observed in the control and 1 kg PL supplementation groups (633.6 and 597.4 IU/L, respectively), whereas alkaline phosphatase (ALP) activity was the highest in the control group (5404 IU/L, P < 0.05). Broilers in the control group had the lowest level of IgY and IgA (122.2 and 25.8 mg/dL, respectively, P < 0.05). Villus height increased by 22.0%, 40.7%, and 34.8% in 0.5, 1, and 2 kg PL supplementation groups, respectively, when compared to the control (P < 0.001). The processed lignocellulose supplemented as 1 kg of PL decreased the average count of Staphylococcaceae, E. coli, and Enterobacteriaceae, whereas it increased the population of Lactobacillus spp. in the cecum (P < 0.05). These data indicate that the supplementation of processed lignocellulose had positive effects for performance via changes in hepatic enzyme activities, immunoglobulin levels, villus growth in jejunum, and microflora in cecum.

Effect of in-ovo feeding of iron nanoparticles and methionine hydroxy analogue on broilers chickens small intestinal characteristics

The experiment was conducted with 644 Ross fertilized egg by 7 treatments 4 replicates and 23 eggs in each. Seven treatments included two control with and without injection, iron sulfate, iron sulfate nanoparticles, Alimet, Alimet + iron sulfate, Alimet + iron sulfate nanoparticles. After hatching 2 mg iron nanoparticles were applied as new treatment. The highest increased in the intestinal relative weight (p < 0.05) was observed by iron+Alimet in late feeding at day old of age. Also similar trend was found in cecum and duodenum length by iron control 2 and late feeding (18 hours’ after hatching). The highest cecum length was found among all treatments by in ovo injection of iron nanoparticles in early feeding at 21 days of age (p < 0.05). Significantly increased the duodenum length was found by iron sulfate in early feeding at 42 days of age (p < 0.05). In ovo injection of Alimet in late feeding was resulted in decrease jejunum crypt depth at 21 days of age (p < 0.05). The results of this study have shown that the highest jejunum villi width and surface area were recorded in dietary iron sulfate nanoparticles in late feeding at 21 and 42 days of age (p < 0.05).

A feed restriction milieu for Pekin meat ducks that may improve gait characteristics but also affects gut leakiness

In a previous study, we demonstrated that a 15% feed restriction (FR) during the first 2 wk after hatch could improve gait in Pekin meat ducks, but did result in reduced breast mass. We hypothesized that feed restriction after day 5 following muscle satellite cell development would allow the full growth of the breast meat. To accomplish this goal, 300 1-day-old ducklings (Maple Leaf Farms Inc.) were randomly allocated to 1 of the 3 groups (n = 4 pens, 25 ducks per pen): (1) Control group fed to ad libitum; (2) 85% daily feed intake from days 1 to 14 (FR 85% 1-14); 85% daily feed intake from days 5 to 14 (FR 85% 5-14). All ducks were vaccinated with inactivated Salmonella enteritidis on day 14 and boosted on day 26. The FR 85% 5-14 did show similar production standards to controls, and improved gait characteristics (P < 0.05). To determine if the partial feed restriction would have an impact on intestinal epithelial tight junction integrity, we treated ducks on days 7, 14, 21, 28, and 35 with 8.32 mg/kg FITC-d in water per os and blood samples were obtained via the tibial vein 1 h later. Serum samples were analyzed for presence and quantification of FITC-d. Feed restriction elicited a significant increase in FITC-d permeability at all points of evaluation. Anti-S. enteritidis specific IgY responses were assessed by ELISA from serum collected at 14 D, 28 D, and 35 D. Although all ducks showed an increase humoral immune response to the S. enteritidis, both feed restricted groups showed reduced IgY production compared to ad lib controls. Our data suggest that although the FR 5-14 feed restriction paradigm may reduce gait abnormalities without affecting production rates, some challenges exist due to increased gut leakiness or decreased acquired immune activity. Future studies will look at altering the feed restriction milieu to ameliorate these challenges.

Effect of dietary supplementation with phytogenic blend on growth performance, apparent ileal digestibility of nutrients, intestinal morphology, and cecal microflora of broiler chickens

The effects of dietary supplementation with phytogenic blend (PB) of Aerva lanata, Piper betle, Cynodon dactylon, and Piper nigrum on growth performance, ileal nutrient digestibility, intestinal morphology, and cecal microflora were determined in a 42-day broiler feeding trial. A total of 192 broilers were assigned to 4 dietary treatments (6 replicates and 8 birds/replicate): basal diet, basal diet supplemented with antibiotic (chlortetracycline), 1% and 2% PB, respectively. The body weight gain (BWG) of starter chicks increased linearly (P = 0.023) as dietary supplementation levels of PB increased. At grower phase, broilers fed diet supplemented with 1% PB had similar BWG with the antibiotic group, but other treatments had reduced (P = 0.0001) BWG. Dietary supplementation with 1% PB resulted in the highest (P < 0.0001) BWG during the study. Feed intake was not affected by the treatments during the starter, finisher, and overall rearing periods. Broilers fed diet supplemented with 1% PB had the best (P < 0.0001) feed conversion ratio during the study. Overall, broilers fed only basal diet had the highest (P = 0.0450) mortality. Ileal organic matter (OM) digestibility increased linearly (P = 0.044) with broilers fed diet supplemented with PB, but reduced with antibiotic group. Dietary supplementation with 1% PB had the highest (P = 0.0402) ileal digestibility of tryptophan. In the duodenum, broilers fed diet supplemented with PB had longer (P = 0.0006) villi heights than the birds fed only basal diet, but similar with antibiotic group. Broilers fed diet supplemented with PB had longer (P = 0.0064) villi height in the jejunum than the antibiotic group. Bifidobacterium concentration of the cecum content showed a slight increase (P = 0.053) with increasing supplementation levels of PB. In conclusion, the current study shows that dietary supplementation with PB improves growth performance, intestinal morphology, and apparent ileal digestibility of OM and tryptophan in a dose-dependent manner with the best response at 1% inclusion level.

Effect of in ovo feeding of amino acids and dextrose solutions on hatchability, body weight, intestinal development and liver glycogen reserves in newborn chicks

Early development of the digestive tract is crucial for achieving maximal growth and development of chickens. This study examined the effects of in ovo (IO) feeding of 0.70 mL of dextrose (10.00% and 20.00%) or amino acids solutions into the yolk sac at day 14 of incubation on small intestine histomorphometry and histomorphology, intestinal development, hatchability, body weight, and liver glycogen reserves in newborn chicks. Results showed body weight in amino acid fed hatchlings was higher than control and dextrose groups non-significantly, but hatchability was lower in amino acid group than others. Also, diameter of glycogen vacuoles in all IO treatment groups was more than control. Administration of exogenous dextrose and amino acids solutions into the yolk sac enhanced intestinal development by increasing the size and surface area of the villi and changed villi shape as well. It seems that dextrose or amino acids solutions could improve the intestinal villi development, while they did not affect finger-like villi in jejunum.

Gross Morphometry, Histomorphometry, and Immunohistochemistry Confirm Early and Persistent Jejunal Crypt Hyperplasia in Poults with Enteritis and Depressed Growth

Phosphorylated histone 3 (PH3) and cleaved caspase 3 (CCASP3) were used to detect proliferating and apoptotic cells, respectively, in the jejunums of female sibling poults, with and without enteritis and depressed growth, from hatch to day 35. Poults that developed enteritis and depressed growth (SIB flock) were raised on a commercial farm in eastern North Carolina, whereas poults with normal growth and no enteritis (TAU flock) were raised in the Teaching Animal Unit at North Carolina State University College of Veterinary Medicine. Beginning on day 5 through day 35 and at processing, TAU poults were significantly heavier than SIB poults. Jejunal weights, relative jejunal weights, and jejunal densities were greater in SIB poults from day 10 through 35. Jejunal efficiency (body weight /jejunal length) was higher in TAU poults at day 5 and days 10 through 35. Mucosal thickness was greater in SIB poults between days 7 and 21 but greater in TAU poults at days 28 and 35. From day 7 to 35, villus-to-crypt ratios were higher for TAU poults and lower for SIB poults because hyperplastic crypts formed a greater percentage of the mucosa in SIB poults. By day 7, PH3- and CCASP3-positive cells were increased in SIB poults, showing that mucosal changes resulted from combined crypt epithelial hyperplasia and increased apoptosis of villous enterocytes. Findings in this study confirm that enteritis, in the absence of clinical signs, and depressed growth in turkey poults begins by day 7, can be identified microscopically, persists for at least 35 days, is associated with lower processing weights, and has a profound negative effect on turkey growth.