Effects of delayed placement on intestinal characteristics in turkey poults

Delayed access to feed early post-hatch affects the development and maturation of gastrointestinal tract microbiota in broiler chickens

Background

The first two weeks of post-hatch (PH) growth in broilers (meat-type birds) are critical for gut development and microbiota colonization. In the current broiler production system, chicks may not receive feed and water for 24 to 72 h due to variations in hatching time and hatchery management. Post-hatch feed delay affects body weight, feed efficiency, mortality, and gut development. The goal of this study was to investigate changes in the microbiome in broiler chickens early PH and the effect of delayed access to feed on the microbiota.

Results

Chicks either received feed and water immediately after hatch or access to feed was delayed for 48 h to mimic commercial hatchery settings (treatment, TRT). Both groups were sampled (n = 6) at -48, 0, 4 h, and 1 (24 h), 2 (48 h), 3 (72 h), 4 (96 h), 6 (144 h), 8 (192 h), 10 (240 h), 12 (288 h) and 14 (336 h) days PH. Ileal (IL) and cecal (CE) epithelial scrapings (mucosal bacteria, M) and digesta (luminal bacteria, L) were collected for microbiota analysis. Microbiota was determined by sequencing the V3-V4 region of bacterial 16S rRNA and analyzed using QIIME2. The microbiota of early ileal and cecal samples were characterized by high abundance of unclassified bacteria. Among four bacterial populations (IL-L, IL-M, CE-L, CE-M), IL-M was the least affected by delayed access to feed early PH. Both alpha and beta diversities were affected by delayed access to feed PH in IL-L, CE-M and CE-L. However, the development effect was more pronounced. In all four bacterial populations, significant changes due to developmental effect (time relative to hatch) was observed in taxonomic composition, with transient changes of bacterial taxa during the first two weeks PH. Delayed access to feed has limited influence on bacterial composition with only a few genera and species affected in all four bacterial populations. Predicted function based on 16S rRNA was also affected by delayed access to feed PH with most changes in metabolic pathway richness observed in IL-L, CE-L and CE-M.

Conclusions

These results show transient changes in chicken microbiota biodiversity during the first two weeks PH and indicate that delayed access to feed affects microbiota development. Proper microbiota development could be an important factor in disease prevention and antibiotic use in broiler chickens. Moreover, significant differences in response to delayed access to feed PH between luminal and mucosal bacterial populations strongly suggests the need for separate analysis of these two populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02619-6.

Evaluation of early feed access and algal extract on growth performance, organ development, gut microbiota and vaccine-induced antibody responses in broiler chickens

Hatching concepts such as on-farm hatching provide an opportunity to supply newly hatched chickens with optimal nutrition that support growth and development of a healthy gut. Brown algae contain bioactive compounds, especially laminarin and fucoidan that may improve intestinal health and immune responses. This study aimed to examine the effects of early access to feed and water posthatch and feed supplementation with algal extract rich in laminarin from Laminaria digitata, on growth performance, organ and microbiota development and antibody production. A total of 432 Ross 308 chicks were allotted to 36 rearing pens in a 2 × 3 factorial design with two hatching treatments and three dietary treatments. During chick placement, half of the pens were directly provided access to feed and water (Early) while half of the pens were deprived of feed and water for 38 h (Late). The chicks were fed three different starter diets until day 6; a wheat-soybean meal-based control diet, a diet with low inclusion of algal extract (0.057%) and a diet with high inclusion of algal extract (0.114%). Feed intake and BW were registered on pen basis at placement, days 1, 6, 12, 19, 26, 33 and 40. To induce antibody responses, all chicks were vaccinated against avian pneumovirus on day 10. Three chicks per pen were selected as focal animals and used for blood sampling on days 10 and 39. On days 6, 19, and 40, two birds per pen were killed and used for organ measurement and caecal digesta sampling for gut microbiota analysis using the Illumina Miseq PE 250 sequencing platform. Results showed that algal extract did not influence gut microbiota, gut development or vaccine-induced antibody responses. However, during the first 38 h, early-fed chicks consumed on average 19.6 g of feed and gained 27% in BW, while late-fed chicks lost 9.1% in BW which lowered BW and feed intake throughout the study (P < 0.05). Late chicks also had longer relative intestine, higher relative (g/kg BW) weight of gizzard and proventriculus but lower relative bursa weight on day 6 (P < 0.05). No effects of hatching treatment on microbiota or antibody response were detected. The microbiota was affected by age, where alpha diversity increased with age. In conclusion, this study showed that early access to feed but not algal extract improved the growth performance throughout the 40-day growing period, and stimulated early bursa development.

Two Blackhead Disease Outbreaks in Commercial Turkey Flocks Were Potentially Exacerbated by Poor Poult Quality and Coccidiosis

Field visits at two different farms suggest a correlation between commercial turkey (Meleagridis gallopavo) flocks having increased mortality from blackhead disease (histomoniasis) if they suffer from poor poult quality at placement and coccidiosis (Eimeria spp.) before age 6 wk. In both cases, the flocks were all-in/all-out with curtain-sided houses and received a coccidiosis vaccine on day of hatch. At Farm I 2018, poults from different hatcheries were placed in two houses on the same farm (Houses 1 and 2). House 2 had poults considered poor quality and suffered from mortality associated with coccidiosis at 2 and 4 wk of age. At 8 wk, blackhead disease was diagnosed in both houses by postmortem examination. House 2 had mortality of >2000 poults, and the subpopulation of necropsied poults had gross lesions characteristic of histomoniasis. Gross lesions associated with blackhead disease were only found in eight poults in House 1, which was populated with good-quality poults and did not have a second spike in mortality due to coccidiosis. The Farm II 2020 poults were delivered from the same hatchery onto a three-house farm (Houses A, B, and C). House C had poults that were considered poor quality and had mortality associated with coccidiosis at 3 wk of age. At 8-9 wk, House C had mortality approaching 1000 birds, with all poults examined postmortem having clinical signs of blackhead disease. Houses A and B were populated with good-quality poults and had no diagnosed mortality from coccidiosis or blackhead disease. The similarity of these two cases suggest that poult quality at placement coupled with coccidiosis before 6 wk of age can influence the severity of blackhead disease in commercial turkey flocks.

Effects of early nutrition and sanitary conditions on antibody levels in early and later life of broiler chickens

Immune maturation of broiler chickens may be affected by management, such as early life feeding strategy (early versus delayed nutrition) or by low or high sanitary conditions (LSC versus HSC). We compared systemic maternal (MAb), natural (NAb), natural auto- (NAAb), and antigen specific antibody (SpAb) levels (IgM, IgY) between broilers (n = 48 per treatment) that received early (EN) or delayed nutrition for 72 h (DN) housed in either low (LSC) or high sanitary conditions (HSC) between 7 and 35 d of age. We found minimal interactions between feeding strategy and sanitary conditions. At 7 d of age, broilers receiving EN compared with DN, had elevated levels of IgM binding keyhole limpet hemocyanin (KLH), phosphoryl-conjugated ovalbumin (PC-OVA), and muramyl dipeptide (MDP), whereas effects of feeding strategy diminished at later ages. In LSC compared with HSC broilers, levels of NAb agglutinating RRBC and sheep red blood cells (SRBC) were already elevated from 14 d of age onwards. At 33 d of age, antibody levels (NAb, NAAb, anti-LPS, anti-MDP) were all elevated in LSC, compared with HSC broilers, for both IgM and IgY, but not IgM against KLH. Western blotting revealed different binding patterns of NAAb against chicken liver homogenate, which may indicate that the NAAb repertoire is affected by antigenic pressure. Our data suggest that antibody levels are affected for an important part by environmental conditions (feeding strategy and sanitary conditions), but minimally by their interaction. However, it remains to be further studied whether the enhanced levels of antibodies as initiated by EN and LSC contribute to enhanced resistance to infectious diseases.

Effects of Betaine Supplementation on Live Performance, Selected Blood Parameters, and Expression of Water Channel and Stress-Related mRNA Transcripts of Delayed Placement Broiler Chicks

This study examined the effect of supplemental betaine on live performance, selected blood parameters, and gene expression of water channel proteins (Aquaporins, AQP) of broiler chicks delayed in placement for 48 h post-hatch. In total, 540 newly-hatched male broiler chicks were obtained from a local hatchery and were randomly allotted to one of five treatments with nine replicates per treatment (12 chicks per replicate). Chicks were either placed immediately, control; held for 48 h post-hatch with no access to feed or water, Holdnull; held for 48 h with free access to drinking water only, HoldW; held for 48 h with free access to drinking water supplemented with 1 ml per L of betaine solution (40% betaine), HoldB1; or held for 48 h with free access to drinking water supplemented with 2 ml per L of betaine solution (40% betaine), HoldB2 group. The results showed that post-hatch holding for 48 h depressed feed intake and body weight gain during the entire 15 d study period with no beneficial effect of supplemental betaine. Chicks in the HoldB2 group had elevated serum glucose, triglycerides, and aspartate aminotransferase 48 h post-hatch. Early water deprivation directly affected the brain proopiomelanocortin (POMC) and hepatic glucocorticoid receptors (GR) expression and induced significant changes in various aquaporins (AQP1, AQP2, AQP4, and AQP9). In conclusion, betaine supplementation to chicks held for 48 h post-hatch resulted in some changes in blood biochemical indices with no effects on performance during the first 15 days of life. The results suggest that betaine supplementation could ameliorate the stressful effects of water deprivation on POMC and GR expression and maintain cellular osmosis through interactions with variable aquaporins expression, particularly the AQP1 and AQP2. Further investigations are required to investigate the molecular mechanisms underlying the selective regulatory expression of different aquaporins in relation to betaine supplementation.

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 Early Nutrition and Sanitary Conditions on Oral Tolerance and Antibody Responses in Broiler Chickens

Greater antigenic exposure might accelerate activation and maturation of the humoral immune system. After hatch, commercial broiler chickens can have early (EN) or delayed (DN) access to nutrition, up to 72 h after hatch. The immune system of EN versus DN broilers is likely more exposed to antigens after hatch. This might contribute to activation and maturation of the immune system, but might also influence the development of oral tolerance, thereby altering later life antibody responses. We studied antibody (IgM, IgY, IgA) responses between 21 and 42 d of age in fast-growing EN and DN broilers, kept under low (LSC) or high sanitary conditions (HSC). In a first experiment (n = 51 broilers), we tested whether early oral exposure to bovine serum albumin (BSA) affected later life antibody responses towards BSA and a novel antigen-rabbit γ-globulin (RGG), under HSC. In a second experiment, a total of 480 EN and DN broilers were housed under either LSC or HSC, and we studied antibody responses against both BSA and RGG (n = 48 broilers per treatment) and growth performance. Broilers kept under LSC versus HSC, had higher antibody levels and their growth performance was severely depressed. Interactions between feeding strategy (EN versus DN) and sanitary conditions, or main effects of feeding strategy, on natural and specific antibody levels, and growth performance were not observed. Levels of IgA were elevated in EN versus DN broilers, in experiment I and in batch 2 of experiment II, but not in the other batches of experiment II. We concluded that EN versus DN contributes minimally to the regulation of antibody responses, irrespective of antigenic pressure in the rearing environment.

Delayed access to feed affects broiler small intestinal morphology and goblet cell ontogeny

Broilers are often deprived of feed and water for up to 48 h after hatch. This delayed access to feed (DAF) can inhibit small intestine development. The objective of this study was to determine the effects of DAF on small intestinal morphology, mRNA abundance of the goblet cell marker Muc2 and absorptive cell marker PepT1, and the distribution of goblet cells in young broilers. Cobb 500 chicks, hatching within a 12-h window, were randomly allocated into 3 groups: control with no feed delay (ND), 24-h feed delay (DAF24), and 36-h feed delay (DAF36). Morphology, gene expression, and in situ hybridization analyses were conducted on the duodenum, jejunum, and ileum at 0, 24, 36, 72, 120, and 168 h after hatch. Statistical analysis was performed using a t test for ND and DAF24 at 24 h. A 2-way ANOVA and Tukey's HSD test (P < 0.05) were used for ND, DAF24, and DAF36 from 36 h. At 24 to 36 h, DAF decreased the ratio of villus height/crypt depth (VH/CD) in the duodenum but increased VH/CD in the ileum due to changes in CD, whereas at 72 h, DAF decreased VH/CD due to a decrease in VH. The mRNA abundance of PepT1 was upregulated, while Muc2 mRNA was downregulated in DAF chicks. Cells expressing Muc2 mRNA were present along the villi and in the crypts. The ratio of the number of goblet cells found in the upper half to the lower half of the villus was greater in DAF chicks than in ND chicks, suggesting that DAF affected the appearance of new goblet cells. The number of Muc2 mRNA-expressing cells in the crypt, however, was generally not affected by DAF. In conclusion, DAF transiently affected small intestinal morphology, upregulated PepT1 mRNA, downregulated Muc2 mRNA, and changed the distribution of goblet cells in the villi. By 168 h, however, these parameters were not different between ND, DAF24, and DAF36 chicks.

Dietary High Sodium Fluoride Impairs Digestion and Absorption Ability, Mucosal Immunity, and Alters Cecum Microbial Community of Laying Hens

(1) Background: This study was conducted to investigate the effects of dietary fluoride (F) on tissue retention, digestive enzymes activities, mucosal immunity, and cecum microbial community of laying hens. (2) Methods: Total of 288 37-week-old Hy-Line Gray laying hens with similar laying rate (85.16% ± 3.87%) were adapted to the basal diets for ten days, and then allocated into three groups at random (n = 9, 6, 6 replicates/group). The concentrations of F in the diets were 31.19 (the control group, CON), 431.38 (F400, low-F group) and 1237.16 mg/kg (F1200, high-F group), respectively. The trial lasted for 59 days. (3) Results: Results suggested that F residuals in duodenum responded to dietary F concentrations positively. The activities of amylase, maltase and lactase were decreased in high-F group, compared with those in the control group. The mRNA expression levels of jejunum and ileum secretory immunoglobulin A (sIgA) and Mucin 2, and sIgA concentrations were decreased inhigh-F group, than those in the control group. The observed operational taxonomic units (OTUs) of laying hens in high-F group were higher than the CON and low-F groups, and the bacterial structure was different from the other two groups. The Lactobacillus was higher in the control group, while Gammaproteobacteria, Escherichia-Shigella, Streptococcaceae, and Enterobacteriaceae were higher in the high-F group. (4) Conclusions: The actual results confirmed that dietary high F intake increased the F residuals in duodenum, and reduced the digestion and absorption of nutrients and immunity via decreasing the activities of digestive enzymes, impairing intestine mucosal immunity, and disturbing the cecum microbial homeostasis of laying hens.

Optimizing Gastrointestinal Integrity in Poultry: The Role of Nutrients and Feed Additives

Immunomodulation of the immune system by stimulating or suppressing one or both arms, is an emerging concept driven by the understanding of the host defense system. In particular, the gastrointestinal tract (GIT) functions not only as a site for digestion and absorption of nutrients but also acts as a metabolic and immunological organ. This serves as a barrier against abnormal presentation of luminal constituents, caused by dysfunctional intestinal epithelial barrier, to the mucosal immune system. Invasion by pathogens in the case of disease or stress or a massive influx of commensal bacteria overcomes the defensive mechanisms, resulting in the full activation of local dendritic cells and the expression of co-stimulatory molecules and pro-inflammatory cytokines. A growing body of literature demonstrates the immune benefits of increasing the intake of specific nutrients. This strategy involves formulating diets that encompass the bioavailability and utilization of nutrients from various food sources and understanding the dynamics of the macro and micronutrients to support all physiological functions as well as maintaining the function of the immune cells. The nature and type of feed ingredients may also play some roles on the integrity of the GIT of birds. Because dietary intake or nutritional status as well as nutrient requirements may be altered as a result of disease or stress, this may eventually alter the gut microflora and intestinal mucosal integrity, resulting in a compromised barrier of the intestinal epithelium. The weakening of the intestinal integrity could result in an increase in bacterial adherence to the mucosa, bacterial translocation, susceptibility to opportunistic bacterial infection, and mis-appropriation of nutrients. In this chapter, we will discuss the role of dietary energy and nutrients as substrates that have the potential to influence GIT's health and integrity and their roles, directly or indirectly, in modulating bird's ability to be resilient or resist infection.

Effect of Zinc Sulfate and Zinc Glycine Chelate on Concentrations of Acute Phase Proteins in Chicken Serum and Liver Tissue

The aim of the study was to determine how inorganic and organic forms of zinc affect the concentrations of C-reactive protein (CRP), serum amyloid A (SAA), alpha-1-acid glycoprotein (α-1-AGP), haptoglobin (Hp), and transferrin (TRF) in the blood and liver tissue of 450 1-day-old Ross 308 chicken. Four experimental groups received one the following: inorganic zinc (ZnSO4), a zinc phytase enzyme supplement (ZnSO4-F), organic zinc in combination with glycine (Zn-Gly), or organic zinc supplemented with phytase (Zn-Gly-F). The chicken serum and liver homogenates were assayed using an ELISA kit. The results of the study showed statistically significantly higher serum and liver concentration of SAA in the group of birds that received zinc sulfate in comparison to the group of birds receiving zinc in organic form. A statistically significantly higher serum concentration of CRP and α-1-AGP was also noted in the group receiving zinc sulfate as compared to the Zn-Gly group. Comparison of the serum concentration of TRF between the supplemented groups showed a statistically significant increase in this parameter in the Zn-Gly-F group as compared to the ZSO4-F group. The increase in the serum concentration of Hp in all groups in comparison to the control may indicate stimulation of local immune mechanisms. The results of this study showed an increase in the concentrations of APPs such as AGP and TRF following the administration of zinc glycine chelates, which may demonstrate their effect on metabolic processes in the liver and on immunocompetent cells that regulate the intensity of the immune response.

Dietary supplementation of L-glutamine and L-glutamate in broiler chicks subjected to delayed placement

This study was conducted to investigate the effect of dietary glutamine (Gln) + glutamic acid (Glu) supplementation on growth performance and physiological stress response in broiler chickens subjected to 24 h delay in placement. Equal number of day-old broiler chicks were assigned to either immediate placement or with 24 h delay in placement with no access to feed and water. Chicks from each placement group were fed either standard starter diet (control) or standard starter diet +1% AminoGut (AG; mixture of 10% Gln and 10% Glu) from 1 to 21 d. Blood and duodenal samples were collected at 21 d for analysis of serum levels of ceruloplasmin (CER), ovotransferin (OVT) and α-1 acid glycoprotein (AGP), duodenal heat shock protein (HSP) 70 expression, and villi length and crypt depth. Results showed that delayed placement for 24 h was detrimental to weight gain during the starter phase (1 to 21 d) but not thereafter. AG supplementation was not able to eliminate that reduction in weight gain and feed intake during the starter stage. However, the observed enhancement in villi length and crypt depth at d 21 resulted in improvement of FCR and weight gain during the finisher stage (22 to 42 d) and consequently the overall period (1 to 42 d). Broiler chickens supplemented with AG also showed lower mortality rate, and higher AGP, OVT, CER, and HSP 70 expression compared to their control counterparts. Based on AGP, OVT, CER, and HSP 70 expression, there is no indication that delayed placement was physiologically stressful to the broiler chickens at 21 d of age.

Stress Levels, Mortality, Intestinal Morphometry and Histomorphology of Chabro Broiler Birds Subjected to Varying Degrees of Post Hatch Delay in Feeding

BACKGROUND AND OBJECTIVE

Kashmir is a part of Jammu and Kashmir State of India where a large chunk of day old chicks are procured from outside the state and these chicks are transported across a distance of hundreds of kilometers over a period of several days. The long distance transport without any access to feed not only subjects the birds to early life stress but also affects their gut morphological development. Therefore, a study was conducted to evaluate the effect of delayed feeding on stress levels, mortality, intestinal morphometry and histomorphology of chabro broiler chicken.

MATERIALS AND METHODS

A total of 400 day old chabro chicks were randomly divided into 5 groups, each group comprising of four replicates of 20 birds. Chicks allotted to group-1 (G 1) were offered feed at hatchery itself whereas feeding in groups G 2, G 3, G 4 and G 5 were initiated at the farm after the delay of 12, 24, 48 and 72 h, respectively.

RESULTS

The results revealed that the heterophil count showed a steady increase from G 1-G 5 and significantly (p<0.05) higher count was found in G 3, G 4 and G 5 compared to G 1. However, the lymphocyte count showed a steady decrease as delay in feeding increased. H:L ratio followed a regular increase from G 1-G 5 and was significantly (p<0.05) higher in G 3, G 4 and G 5 compared to G 1. An overall mortality of 13% was recorded during the trial and all of it occurred during first 2 weeks. The highest overall mortality of 22.50±3.23% was recorded in group G 5 followed by 17.50±6.61% in G 4. The villus height of duodenum and jejunum was significantly (p<0.05) higher in G 2, G 3, G 4 and G 5 as compared to G 1. Crypt depth and muscular is thickness of duodenum was significantly (p>0.05) lower in G 4 and G 5 compared to G 1.

CONCLUSION

The duration of post hatch feeding delay gradually increased the stress level and mortality of birds and also decreased the length of different segments of small intestine in birds. No adverse effect on histomorphology was observed at the end of trial. Feeding at hatchery itself or feeding during transportation of birds would be a viable strategy to overcome the negative effects of delayed feeding in chicken.

Early intestinal growth and development in poultry

While there are many accepted "facts" within the field of poultry science that are in truth still open for discussion, there is little debate with respect to the tremendous genetic progress that has been made with commercial broilers and turkeys (Havenstein et al., 2003, 2007). When one considers the changes in carcass development in poultry meat strains, these genetic "improvements" have not always been accompanied by correlated changes in other physiological systems and this can predispose some birds to developmental anomalies (i.e. ascites; Pavlidis et al., 2007; Wideman et al., 2013). Over the last decade, there has been increased interest in intestinal growth/health as poultry nutritionists have attempted to adopt new approaches to deal with the broader changes in the overall nutrition landscape. This landscape includes not only the aforementioned genetic changes but also a raft of governmental policies that have focused attention on the environment (phosphorus and nitrogen excretion), consumer pressure on the use of antibiotics, and renewable biofuels with its consequent effects on ingredient costs. Intestinal morphology has become a common research tool for assessing nutritional effects on the intestine but it is only one metric among many that can be used and histological results can often be interpreted in a variety of ways. This study will address the broader body of research on intestinal growth and development in commercial poultry and will attempt to integrate the topics of the intestinal: microbial interface and the role of the intestine as an immune tissue under the broad umbrella of intestinal physiology.

Prospects of in ovo feeding and nutrient supplementation for poultry: the science and commercial applications--a review

In ovo supplementation of poultry embryos was first reported several decades ago, but it is only recently that concerted research has been directed at developing the technology for this process to be routinely used by the poultry industry. Although the technology of in ovo feeding was patented more than 10 years ago, it has not been widely adopted by the poultry industry. This review examines the early development of the enteric system of the poultry embryo; defines and distinguishes between in ovo feeding and in ovo nutrient administration; highlights the importance of early feeding of the chick; and discusses the development of in ovo feeding technology and its effects on hatchability, growth, gut health and immune response of chicks. The range of possible nutrients that can be administered is also explored. The limitations associated with embryo development and nutrient metabolism are highlighted, leading to the prediction of the future role of in ovo feeding in the poultry industry.

Ultrastructural development of the small intestinal mucosa in the embryo and turkey poult: A light and electron microscopy study

The potential for growth and feed efficiency in turkey poults directly correlates with the early development of the intestinal epithelium. Although the metabolic aspects of enteric maturation have been studied, little is known about the ultrastructural development of the enteric epithelium in the turkey embryo and poult. Hence, the objective of this study was to document the morphological and ultrastructural development of the jejunum mucosa in turkeys, from 15 d of incubation (embryonic day; E) to 12 d posthatch. Intestinal samples from 4 embryos or poults were collected and analyzed by light and electron microscopy (transmission and scanning). In addition, amniotic fluid volume was determined in 6 eggs from E15 to E25. Longitudinal previllus ridges at E15 gradually formed zigzag patterns that led to the formation of 2 parallel lines of mature villi by E25. The volume of amniotic fluid was rapidly depleted as the embryo swallowed it between E19 and E25. During this period, a major increase occurs in villus height, the apical end of epithelial cells is gradually tightened by the junctional complex, and mature goblet cells are visible at the apical end of villi. Villus height steadily increases until reaching a plateau at 8 d. Villi morphology shifts gradually from finger-like projections before hatch to leaf-like projections by 12 d. At this age, the enteric epithelium is in intimate association with microbes such as segmented filamentous bacteria. The profound morphological adaptations of the turkey gut epithelium in response to amniotic fluid swallowing before hatch, and dietary factors and bacteria after hatch, demonstrate the plasticity of the enteric epithelium at this time. Hence, the supplementation of enteric modulators before hatch (in ovo feeding) and after hatch has the potential to shape gut maturation and enhance the growth performance of turkey poults.

Developmental changes in insulin-like growth factor (IGF)-I and -II mRNA abundance in extra-embryonic membranes and small intestine of avian embryos

OBJECTIVE

Numerous researchers have evaluated the insulin-like growth factors (IGF) influence on mammalian fetal development. Although IGF has been explored in the avian system, questions remain on the role of IGF in avian development. Therefore, the current study evaluated the mRNA abundance of IGF in the amnion and allantoic membranes and developing small intestine in the chicken, duck, and turkey during the incubation and post-hatch period.

DESIGN

Broiler, duck, and turkey eggs were incubated with small intestinal, allantoic, and amniotic membranes collected in the final days of incubation and 1 week post-hatch. RNA was extracted using Trizol and qRT-PCR was utilized to compare differences during embryo development within and across species.

RESULTS

The expression of the IGF mRNA varied between species in the final days of incubation in the amniotic and allantoic membranes. The turkey had higher (0.38-1.72 log) transcript abundance of IGF-I and IGF-II in the amnion and allantois compared to the chicken and duck. Evaluating the mRNA abundance within the chicken duodenum, jejunum, and ileum, the duodenum had the lowest expression of IGF-I and IGF-II (P<0.05) at day -4 of incubation compared to the jejunum and ileum. Focusing on differences in jejunal IGF expression among the three species, the turkey had the lowest IGF-I abundance at day -4 of incubation and highest IGF-I abundance at day of hatch (P<0.05). Transcript abundance of both IGF-II and IGF-R was highest in the turkey at day of hatch and day 1 post-hatch compared to the duck and chicken. The whole tissue versus the mucosal expression of the IGF mRNA abundance was evaluated during the post-hatch period. Duodenal, jejunal, and ileal segments had higher IGF-I transcript abundance (P<0.05) at day 1, day 3, and day of hatch, respectively. No differences were observed between segment and mucosa for IGF-II in the post-hatch period. The duodenal and jejunal mucosa IGF-R transcript abundance was greater (P<0.05) at day of hatch compared to the intestinal segment. The duck IGF mRNA in the jejunal mucosa was higher than the whole segment and decreased from day of hatch to day 3 post-hatch while the IGF mRNA abundance increased in the whole segment during the same time period. The turkey IGF-I transcript abundance decreased in both the segment and mucosa following hatch while the IGF-II mRNA expression increased by 1.5 logs from hatch to day 1 post-hatch.

CONCLUSION

The transcript abundance of the IGF axis in the extra-embryonic membranes and gastrointestinal tissue of the developing chicken, duck, and turkey are influenced by embryonic age and species. A better understanding of the IGF axis in the small intestine during embryonic development may allow for increasing the optimal growth of both the gastrointestinal tract and the neonate.

Factors affecting intestinal health in poultry

The gastrointestinal (GI) tract has the most extensive exposed surface in the body and is constantly exposed to a wide variety of potentially harmful substances. The GI tract acts as a selective barrier between the tissues of the bird and its luminal environment. This barrier is composed of physical, chemical, immunological, and microbiological components. A wide range of factors associated with diet and infectious disease agents can negatively affect the delicate balance among the components of the chicken gut and, as a result, affect health status and production performance of birds in commercial poultry operations. Phasing out of antibiotic growth promoters from poultry diets in Europe and recent moves toward reduction or removal of these compounds in other parts of the world including North America will likely change the microbial profile of the GI tract environment in commercial poultry. This paper reviews the GI tract from developmental, immunological, and microbial standpoints and then discusses factors that can affect health status of this system. Necrotic enteritis and coccidiosis and their interactions, and possible consequences of antibiotic growth promoter removal from poultry diets with respect to these diseases, are discussed in more detail.

Gastrointestinal Maturation is Accelerated in Turkey Poults Supplemented with a Mannan-Oligosaccharide Yeast Extract (Alphamune)

Alphamune, a yeast extract antibiotic alternative, has been shown to stimulate the immune system, increase BW in pigs, and reduce Salmonella colonization in chickens. The influence of Alphamune on gastrointestinal tract development has not been reported. Two trials were conducted to evaluate the effects of Alphamune on gut maturation of 7- and 21-d-old turkey poults. Poults were fed a standard control unmedicated turkey starter diet or the same diet supplemented with either 1 or 2 lb/ton of Alphamune (n = 18/group). Poults were weighed on d 7 and 21, euthanized, and a 2-cm section was collected from the midpoint of the duodenum, jejunum, and ileum of each bird (9 poults/d per treatment) and fixed in a 10% formalin solution for 72 h and then stained. Twenty measurements of villus height, villus surface area, lamina propria thickness, crypt depth, and density of neutral, sialomucin, and sulfomucin goblet cells were taken per section per poult. On d 7, BW were higher for the poults given the Alphamune treatments compared with control poults; however, no differences were observed on d 21. Alphamune supplementation influenced intestinal morphology differently based on gut location. Ileum villus height, surface area, lamina propria thickness, crypt depth, and neutral, sialomucin, and sulfomucin goblet cell density were enhanced with Alphamune treatments on d 7 and 21 (P < 0.05) and in a dose-dependent manner for many of the parameters evaluated. Jejunum results were mixed. Surface area, crypt depth, and sialomucin and sulfomucin goblet cells were consistently higher for the 2 lb/ton of Alphamune groups compared with the control group on d 7 and 21. Duodenum villus height, surface area, and goblet cell density were higher for the 2 lb/ton of Alphamune groups on d 7; however, intestinal morphology of the duodenum was not different between the control and treated birds on d 21. These results suggest that feed supplemented with Alphamune can accelerate gastrointestinal maturation in turkey poults and is more pronounced in the ileum than in other portions of the small intestine.

Turkey breeder hen age affects growth and systemic and intestinal inflammatory responses in female poults examined at different ages posthatch

This trial examined the effect of 2 turkey breeder hen ages (33 or 55 wk of age) on performance, intestinal histology, and inflammatory immune response of female turkey poults grown to market weight. Using a randomized design, female poults were separated by breeder flock age (n = 8 floor pens/breeder flock age; n = 26 poults/pen; 0.195 m(2)/bird), fed identical commercial diets (9 phases), and grown to market weight (approximately 11.4 kg/ bird). At young ages, poults from the older breeder flock tended to have higher BW (P < 0.01 for d 7, P < 0.09 for d 63), although feed consumed was not significantly different due to breeder flock age (P > 0.20 for all ages). After approximately 63 d posthatch, no difference in BW was observed, suggesting that poults from the younger breeder flock were eventually able to compensate for initial reductions in performance. In addition to growth measurements on d 10, 24, and 65 posthatch, poults were vaccinated with lipopolysaccharide (LPS, from Salmonella Typhimurium; 0.5 mg/kg of BW intraabdominally) or not vaccinated (control), and intestinal histology and plasma haptoglobin were assessed at 24 h postadministration. In control birds, intestinal villus length was greater for poults from the older breeder flock (P < 0.05), as was crypt depth (P < 0.05 for d 11 and 25). Plasma haptoglobin levels did not change in 11-d-old poults after LPS administration, but they increased with LPS at d 25 and 66 posthatch (P < 0.05 for each). At d 66 posthatch, poults from the younger flock had increased haptoglobin levels post-LPS compared with those from the older breeder flock (P < 0.05). In general, LPS administration increased villus width in the jejunum and ileum (P < 0.05 for each), increased lamina propria width in the duodenum and ileum (P < 0.05 for each), and decreased ileum crypt depth (P < 0.05). Overall, poults from the older breeder flock had reduced inflammatory responses, even at 9 to 10 wk posthatch, even though performance was similar in poults from the 2 flocks by this age.