Comparative development of the small intestine in the turkey poult and Pekin duckling

Effects of Dietary Bacillus and Non-starch Polysaccharase on the Intestinal Microbiota and the Associated Changes on the Growth Performance, Intestinal Morphology, and Serum Antioxidant Profiles in Ducks

Given the desirable results of using probiotics and enzyme preparations as feed supplements in poultry health, here, the effects of Bacillus and Non-starch Polysaccharase (NSPase) on the growth performance, serum antioxidant profiles, and gut microbial communities of early stage ducks is investigated. A total of 400 Zhijiang ducks (of similar body weight and 1 day age) was selected and randomly divided into four groups. The feeding period was 28 days. Each group contained 10 replicates of 10 birds. Control group (I) was fed with basal diet, while treatment groups II to IV were fed, respectively, with 150 mg/kg NSPases, 25 mg/kg Bacillus probiotics, and 150 mg/kg NSPases + 25 mg/kg Bacillus probiotics in their basal diet. The results demonstrated that dietary Bacillus (25 mg/kg) increased average final weight, average daily gain (ADG), and decreased the malonaldehyde (MDA) in birds (P < 0.05). Dietary Bacillus (25 mg/kg) and NSPases + Bacillus (150 mg/kg + 25 mg/kg) presented much higher glutathione (GSH) and activities of superoxide dismutase (SOD) in birds (P < 0.05). Additionally, as revealed by β-diversity indices and analysis of similarities, dietary NSPases + Bacillus could affect the ileum microbial abundances and diversities at the genera level (P < 0.05), but it had no effect on the caecal microbiota. Also, 16S rRNA sequencing revealed that dietary Bacillus and NSPases + Bacillus increased the populations of Ruminococcaceae genera in the cecum (P < 0.05), and S24-7_group and Lactobacillus genera in the ileum (P < 0.05). However, dietary NSPases and Bacillus alone and in combination could significantly decrease the content of Bacteroides in the ileum (P < 0.05). According to Spearman correlation analysis, 7 ilea bacterial microbiomes (S24-7 group, Lactobacillus, Subgroup 2, Subgroup 1, Kitasatospora, Candidatus Solibacter, and Akkermansia) were positively correlated with SOD (P < 0.05). In conclusion, Bacillus (25 mg/kg) and NSPases (150 mg/kg) included in the diet could efficiently enhance the growth performance by altered gut microbiota composition at the genera level and antioxidant indices of ducks.

High doses of phytase on growth performance, bone mineralization, diet utilization, and plasmatic myo-inositol of turkey poults

An experiment was conducted to evaluate the growth performance, bone mineral composition, diet utilization, and plasmatic concentration of myo-inositol (MYO) in turkeys fed different phytase doses from 1 to 28 d. A total of three hundred and twenty 1-day-old turkeys were distributed in a completely randomized design with 4 treatments and 8 replicates of 10 birds each. Treatments included a basal diet without phytase; reduced diet (reduced -0.15% available P and -0.18% Ca) without phytase; reduced diet + 2,000 units of phytase (FYT)/kg; and reduced diet + 4,000 FYT/kg. From day 26 to 28, partial excreta collection was conducted, and on day 28, 7 birds per replicate were euthanized for collection of ileal content and left tibia bones were removed from 2 of the same euthanized birds. Feed, excreta, and ileal digesta samples were analyzed to determine nutrient digestibility and metabolizability, ileal digestible energy, and AME. Tibia bones were analyzed for ash, Ca, and P content, and calculation of Seedor index. On day 28, blood samples were collected from 2 turkeys per replicate to analyze plasmatic MYO concentration. Feed conversion ratio was not affected, but phytase supplementation resulted in higher feed intake and body weight gain compared to turkeys fed the reduced diet (P < 0.05), and both doses were similar to the basal diet. Increasing the phytase dose had a linear effect (P < 0.05) on ileal digestibility of P and metabolizability of DM, CP, Ca, and Na, and also on AME. P content in the tibia bone increased linearly (P < 0.05) with phytase supplementation, and the same linear increase (P < 0.05) was observed for plasmatic MYO. In conclusion, the supplementation of turkey poult's diets with high levels of phytase up to 4,000 FYT/kg improves diet utilization by increasing P digestibility and dietary metabolizability, leading to higher P content in the bone and enhancing MYO provision and absorption.

An altered gut microbiota in duck-origin parvovirus infection on cherry valley ducklings is associated with mucosal barrier dysfunction

Duck-origin parvovirus disease is an epidemic disease mainly caused by duck-origin goose parvovirus (D-GPV), which is characterized by beak atrophy and dwarfism syndrome. Its main symptoms are persistent diarrhea, skeletal dysplasia, and growth retardation. However, the pathogenesis of Cherry Valley ducks infected by D-GPV has not been studied thoroughly. To perceive the distribution of D-GPV in the intestinal tract, intestinal morphological development, intestinal permeability, inflammatory cytokines in Cherry Valley ducks, and expression of tight junction protein, the D-GPV infection was given intramuscularly. Illumina MiSeq sequencing technology was used to analyze the diversity and structure of ileum flora and content of short-chain fatty acids of its metabolites. To investigate the relationship between intestinal flora changes and intestinal barrier function after D-GPV infection on Cherry Valley ducks is of great theoretical and practical significance for further understanding the pathogenesis of D-GPV and the structure of intestinal flora in ducks. The results showed that D-GPV infection was accompanied by intestinal inflammation and barrier dysfunction. At this time, the decrease of a large number of beneficial bacteria and the content of short-chain fatty acids in intestinal flora led to the weakening of colonization resistance of the intestinal flora and the accumulation of potentially pathogenic bacteria, which would aggravate the negative effect of D-GPV damage to the intestinal tract. Furthermore, a significant increase in Unclassified_S24-7 and decrease in Streptococcus was observed in D-GPV persistent, indicating the disruption in the structure of gut microbiota. Notably, the shift of microbiota was associated with the transcription of tight-junction protein and immune-associated cytokines. These results indicate that altered ileum microbiota, intestinal barrier, and immune dysfunction are associated with D-GPV infection. Therefore, there is a relationship between the intestinal barrier dysfunction and dysbiosis caused by D-GPV, but the specific mechanism needs to be further explored.

Physiological parameter values for physiologically based pharmacokinetic models in food-producing animals. Part II: Chicken and turkey

Physiologically based pharmacokinetic (PBPK) models are growing in popularity due to human food safety concerns and for estimating drug residue distribution and estimating withdrawal intervals for veterinary products originating from livestock species. This paper focuses on the physiological and anatomical data, including cardiac output, organ weight, and blood flow values, needed for PBPK modeling applications for avian species commonly consumed in the poultry market. Experimental and field studies from 1940 to 2019 for broiler chickens (1-70 days old, 40 g - 3.2 kg), laying hens (4-15 months old, 1.1-2.0 kg), and turkeys (1 day-14 months old, 60 g -12.7 kg) were searched systematically using PubMed, Google Scholar, ProQuest, and ScienceDirect for data collection in 2019 and 2020. Relevant data were extracted from the literature with mean and standard deviation (SD) being calculated and compiled in tables of relative organ weights (% of body weight) and relative blood flows (% of cardiac output). Trends of organ or tissue weight growth during different life stages were calculated when sufficient data were available. These compiled data sets facilitate future PBPK model development and applications, especially in estimating chemical residue concentrations in edible tissues to calculate food safety withdrawal intervals for poultry.

Effect of a post-hatch lipopolysaccharide challenge in Turkey poults and ducklings after a primary embryonic heat stress

The effect of embryonic thermal manipulation on the post-hatch immune response to a lipopolysaccharide (LPS) challenge was studied in Pekin ducklings and turkey poults. Commercial duck and turkey eggs were distributed among four treatments: SS-Control (37.5 °C from embryonic day [ED] 1 to 25); SS-LPS (37.5 °C from ED1 to 25 + LPS at D0 [hatch]); HH-LPS (38 °C from ED1 to 25 + LPS at D0; SH-LPS (37.5 °C from ED1 to 10 and 38 °C from ED 11 to 25 + LPS at D0). At ED16 and ED24, the egg shell temperature of the duck and turkey eggs in the HH and SH treatments were higher (P ≤ 0.01) than the SS treatment. Ducklings and poults in the HH treatment had the lowest yolk free body weight at hatch (P ≤ 0.05). At 24, 48, and 72 h post-LPS injection, ducklings and poults in the HH-LPS treatment had significantly reduced BW compared with the SS-Con treatments (P ≤ 0.05). Ducklings and poults in the SH-LPS and HH-LPS treatments had increased plasma heat shock protein 70 (HSP70) and lower splenic HSP70 mRNA amounts than the SS-LPS treatments at 24, and 48 h post-challenge (P ≤ 0.05). At 48 and 72 h, macrophage nitric oxide (NO) production in ducklings and poults in the SH-LPS and HH-LPS treatments was lower than in the SS-LPS treatments (P ≤ 0.05). Ducklings and poults in the SH-LPS treatment had increased thymocyte proliferation compared to the SS-LPS treatment at 24, 48 and 72 h (P ≤ 0.05). At 24 h, ducklings in the SH-LPS treatment had increased splenic IL-10 and reduced IFNγ and IL-6 mRNA abundance. However, both ducklings and poults in the HH-LPS treatment had increased IFNγ, and IL-10 mRNA abundance compared to the SS-LPS treatment (P ≤ 0.05). At 48 h, SH-LPS ducklings and poults had lower splenic IL-10 mRNA abundance (P ≤ 0.05) while the HH-LPS treatment resulted in comparable splenic IL-10 mRNA compared to the SS-LPS treatment (P ≥ 0.05). Ducklings and poults in the SH-LPS treatment had increased thymic and splenic CD8⁺/CD4⁺ ratios at 24 h versus the SS-LPS treatment (P ≤ 0.05). In conclusion, embryonic thermal manipulation from ED11-25 increased extracellular HSP70 release, thymocyte proliferation and IL-10 but decreased splenic HSP70 and IFNγ mRNA amounts at 24 h post-LPS injection. This suggests that mild heat stress during the later stages of incubation could potentially prime the embryonic immune system thereby enhances the immune response as earlier than 24 h to eliminate the inflammatory response without affecting the growth performance by increase the extracellular release of HSP70 in both ducklings and poults. Continuous exposure to the small increase in temperature from ED 1-25 (HH) caused an imbalance between pro (IFNγ)- and anti-inflammatory cytokines(IL-10) which affects hatchling responses to an inflammatory challenge and increased mortality. The amount of extracellular HSP70 could potentially play an important role in modulating the immune response against inflammatory challenges.

Digestive tract morphometry and breast muscle microstructure in spent breeder ducks maintainedin a conservation programme of genetic resources

Abstract. The objective of this study was to compare three genetic groups of ducks: P9 (French Pekin), K2 (bred from wild mallards – Anas platyrhynchos L. and Pekin duck), and KhO1 (hybrid of Khaki Campbell drake and Orpington Fauve duck) after two breeding seasons for body weight and length, length of intestine and its segments, percentage of other internal organs, and breast muscle microstructure. The study used 60 ducks, 20 birds (10 males and 10 females) from each genetic group. At 110 weeks of age, P9 ducks exhibited significantly (p<0.05) greater body weight and length, and length of intestine and its segments (except for colon length) compared to K2 and KhO1 ducks. KhO1 ducks had significantly shorter jejunum and ileum compared to K2 birds. The lighter K2 and KhO1 ducks had significantly greater relative length of intestine and its segments. In P9 ducks, liver, heart, and gizzard were heavier and spleen percentage in body weight significantly lower than in K2 and KhO1 birds. KhO1 ducks had a significantly higher percentage of proventriculus compared to the other duck groups. The different genetic origins of the ducks had no effect on microstructural characteristics of m. pectoralis superficialis except for perimysium and endomysium thickness. Our study provided information about differences in the digestive tract morphometry and breast muscle microstructure of ducks from three genetic groups after two reproductive seasons, which are maintained in a conservation programme of genetic resources in Poland.

Effect of Zinc Supplementation on Growth Performance, Intestinal Development, and Intestinal Barrier-Related Gene Expression in Pekin Ducks

The current study was conducted to investigate the effect of zinc supplementation on the growth performance, intestinal morphology, and the transcription of the barrier function related genes in Pekin ducks. Seven-hundred and sixty-eight 1-day-old Pekin ducks were randomly assigned into six dietary treatments. Each treatment had eight replicates with 16 ducks per replicates. The ducks were fed either a corn-soybean meal basal diet or basal diets supplemented with 15, 30, 60, 120, and 240 mg zinc/kg from zinc sulfate. This experiment lasted for 5 weeks, and the jejunum sample were harvested at 14 and 35 days of age. Results have shown that diets supplemented with zinc significantly increased the duck body weight, average daily gain, and average daily feed intake in different period of experiment (P < 0.05); feed to gain ratio was decreased as the zinc level increased (P < 0.05). Zinc supplementation increased the villus height and decreased the crypt depth in jejunum of ducks (P < 0.05) at 14 and 35 days of age. The transcription of tight junction protein CLDN1, OCND, ZO-1, and ZO-3 in jejunum were increased (P < 0.05), and the messenger RNA (mRNA) levels of leak protein CLDN2 were decreased as the dietary zinc level increased (P < 0.05) at 14 and 35 days of age. The mRNA levels of chemical barrier-related genes MUC2 and TFF-2 in jejunum at 14 and 35 days of age were increased (P < 0.05) by zinc supplementation, and so did the transcription of immunological barrier-related genes lgA, pIgR, LYZ, and AvBD2 (P < 0.05). In conclusion, dietary zinc supplementation exhibited growth-promoting effect on Pekin duck, improved intestinal morphology, and enhanced the intestinal barrier integrity.

Magnolol additive as a replacer of antibiotic enhances the growth performance of Linwu ducks

Magnolol rich in Magnolia officinalis is a bioactive polyphenolic compound. The aim of this study was to examine the effects of magnolol additive (MA) on growth performance, expression levels of antioxidant-related genes, and intestinal mucosal morphology of Linwu ducks aged from 49 to 70 days, comparing with that of an antibiotic additive (colistin sulfate [CS]). A total of 275, 49-day-old ducks were assigned to 5 groups with 5 cages of 11 ducks each and fed diets supplemented with 0, 100, 200 and 300 mg of MA/kg and 300 mg of CS/kg for 3 weeks, respectively. The results showed that the average daily body weight gain (ADG) was increased significantly in MA-fed groups (200 and 300 mg/kg), compared with the basal diet (BD) group (P < 0.05). The mRNA levels of superoxide dismutase-1 (SOD1), manganese superoxide dismutase-2 (MnSOD2) and catalase (CAT) were also increased significantly in MA groups (P < 0.05). In addition, hematoxylin and eosin staining revealed that Linwu ducks fed the diets with MA had more intact intestinal mucosa than those fed the BD and CS diets. In addition, ileal villus height, ileal villus height/crypt depth ratio (V/C) and duodenal V/C were also improved significantly (P < 0.05). Taken together, these data demonstrated that MA is an effective feed additive to enhance the growth performance of the Linwu ducks by improving the antioxidant and intestinal mucosal status, suggesting that MA will be a potential additive to replace antibiotic (CS).

Characterization of Gut Microbiome Dynamics in Developing Pekin Ducks and Impact of Management System

Little to no research has been conducted on the gut microbiome of the Pekin duck, yet over 24.5 million ducks are raised for human consumption each year in the United States alone. Knowledge of the microbiome could lead to an understanding of the effects of growing conditions such as the use of prebiotics, probiotics, and enzymes in feeding practices, the use of antibiotics, and the sources of pathogenic bacteria in diseased ducks. In order to characterize changes in the caecal microbiome that occur as ducks develop through a typical industry grow-out period, a 16S rRNA community analysis of caecal contents collected over a 6-week period was conducted using a next generation sequencing approach. Transitions in the composition of the caecal microbiome occurred throughout the lifespan, with a large shift during days 4 through 10 posthatch. Two major phyla of bacteria were found to be present within the caeca of aviary raised ducks, with the relative abundance of each phylum varying by age of the duck. Proteobacteria is dominant for the first 3 days of age, and Firmicutes increases and dominates beginning at day 4. Barn raised ducks contained a significant population of Bacteroidetes in addition to Proteobacteria and Firmicutes at later developmental time points, though this phylum was absent in aviary raised ducks. Genera containing pathogens of anseriformes most often found in industry settings were either absent or found as normal parts of the caecal microbial populations. The high level differences in phylum abundance highlight the importance of well-designed sampling strategies for microbiome based studies. Results showed clear distinctions between Pekin Duck caecal contents and those of Broiler Chickens and Turkey in a qualitative comparison. These data provide a reference point for studies of the Pekin Duck through industry grow-out ages, provide a foundation for understanding the types of bacteria that promote health, and may lead to improved methods to increase yields and decrease instances of disease in agricultural production processes.

Early intestinal development and mucin transcription in the young poult with probiotic and mannan oligosaccharide prebiotic supplementation

Alternative and adjunctive approaches to decreasing the use of dietary antibiotics are becoming popular areas of study. Supplemental probiotics (commensal microbes) and prebiotics (indigestible complex carbohydrates) are 2 dietary approaches to facilitating the intestinal colonization of beneficial bacteria to compete with potential pathogens, thus creating a healthy mucosal environment. The intestinal mucosa is composed of mucin glycoproteins, which play a key role in preventing the attachment of pathogenic bacteria. At hatch, the neonatal turkey intestine is relatively aseptic and vulnderable to bacterial colonization by both commensal and pathogenic microbes. In the current study, we determined the transcription of MUC2, the primary mucin protein produced by goblet cells within the small intestine, and we also measured intestinal morphology immediately post-hatch through d 11. Poults were fed a conventional starter diet, the starter diet supplemented with one of 2 commercial probiotics (A, B), or a commercial mannan oligosaccharide. MUC2 transcription increased from d zero to d 4 post-hatch (P< 0.05), but there was no effect of probiotic or prebiotic supplementation. Villus height and villus area both increased with Probiotic B and mannan oligosaccharide supplementation (P<0.05) and there was a significant d X treatment interaction effect for crypt depth (P=0.007). These results suggest that probiotic and prebiotic supplementation can positively alter the intestinal microenvironment.

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.

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.

Dynamics of yolk sac content absorption and intestine development in ducklings fed mixtures with increasing dietary methionine level

The experiment was carried out with ducklings fed-control feed mixture (Met level 0.3%) and mixtures supplemented with dl-methionine at the dose of 0.03 (II); 0.07 (III) 0.12 (IV) and 0.18% (V). In 5 h post-hatch (12 birds) and on days 3, 4, 6 always 18 birds were taken out from each treatment and killed, then the yolk sac (YS) and intestine were removed. The weight and chemical composition of YS residues (in them also amino acids) were analysed. Moreover on days 1, 3, 4 and 6, the amino acid pattern of YS residual protein was elaborated as well as length and weight of intestine were recorded. Increased doses of supplemental Met improved body weight gain after 4 days of ducklings life. All determined parameters were not affected by treatment. Development of intestines, yolk sac weight and yolk sac composition (DM, fat, protein, amino acid composition) changed with age; however, without any clear effect from dietary methionine level. No differences between sex and analysed parameters were stated.

Comparison of Amino Acid Digestibility in Broiler Chickens, Turkeys, and Pekin Ducks

The objective of this study was to compare prececal amino acid (AA) digestibilities in broilers, turkeys, and Pekin ducks that were 3 wk old. Five diets were used: a basal diet and diets that contained either soybean meal (SBM) or rapeseed meal (RSM) at the expense of starch each at either 150 or 300 g/kg. The differences in dietary CP and AA concentrations resulted only from the inclusion of SBM or RSM. Titanium dioxide was used as an indigestible marker. Each diet was allocated to 6 pens of 12 birds from each species and provided ad libitum for 1 wk starting at 14 d of age. Digesta were sampled on a pen basis from the distal two-thirds of the section between Meckel's diverticulum and 2 cm anterior to the ileocecocolonic junction. Ingested and digested amounts of AA were determined for each pen. Digestibilities for the 2 meals were then determined by a multiple linear regression analysis, which makes a correction for basal endogenous AA losses unnecessary. Digestibilities for essential AA from the meals varied between 92% (Met, RSM, broilers) and 62% (Val, RSM, ducks). Digestibilities were not significantly different between SBM and RSM for broilers and turkeys, but the average digestibility across all AA was slightly higher for SBM and lower for RSM in turkeys than in broilers. Digestibilities were lower in ducks than in the 2 other species, and significant differences between SBM and RSM were detected for some AA in ducks. Amino acid digestibility ranking was very similar between broilers and turkeys but different for the 2 meals. It was concluded that differences among species cannot be explained by differences in basal endogenous AA losses among species. Amino acid digestibilities determined with broilers should not be used in formulating feed for ducks.

Developmental changes in amniotic and allantoic fluid insulin-like growth factor (IGF)-I and -II concentrations of avian embryos

In the literature, IGFs in the developing embryo are usually determined by blood serum concentrations. For this study, IGF-I/-II was quantified in the amniotic and allantoic fluids of fertile commercial broiler chicken (Gallus domesticus) (n=222), Pekin duck (Anas platyrhyncha) (n=250), and turkey (Meleagridis gallopavo) eggs (n= 200) during incubation. Amniotic and allantoic fluids were collected from embryos starting at 6 days of incubation for chickens and 8 days of incubation for ducks and turkeys. IGF concentrations within the fluids were determined by radioimmunoassay. Chicken amniotic IGF-I concentration at stage 29 of development was significantly higher (P< or =0.05) than the duck or turkey. At stage 36 of development the concentration of IGF-II in the amniotic fluid was 2.8 times greater in the chicken versus the duck (P< or =0.05) and 2 times greater than in the turkey (P< or =0.05). Within species, chicken IGF-I concentration in the amniotic fluid had a cubic trend (P< or =0.001), duck IGF-I increased linearly (P< or =0.001), and turkey concentrations declined quadratically (P< or =0.001) throughout development. In all species, the IGF-II concentration was higher than the IGF-I concentration in the amniotic and allantoic fluids.