Dietary xylo-oligosaccharides and arabinoxylans improved growth efficiency by reducing gut epithelial cell turnover in broiler chickens.

BACKGROUND: One of the main roles of the intestinal mucosa is to protect against environmental hazards. Supplementation of xylo-oligosaccharides (XOS) is known to selectively stimulate the growth of beneficial intestinal bacteria and improve gut health and function in chickens. XOS may have an impact on the integrity of the intestinal epithelia where cell turnover is critical to maintain the compatibility between the digestive and barrier functions. The aim of the study was to evaluate the effect of XOS and an arabinoxylan-rich fraction (AXRF) supplementation on gut function and epithelial integrity in broiler chickens. METHODS: A total of 128 broiler chickens (Ross 308) were assigned into one of two different dietary treatments for a period of 42 d: 1) control diet consisting of a corn/soybean meal-based diet; or 2) a control diet supplemented with 0.5% XOS and 1% AXRF. Each treatment was randomly distributed across 8 pens (n = 8) with 8 chickens each. Feed intake and body weight were recorded weekly. On d 42, one male chicken per pen was selected based on average weight and euthanized, jejunum samples were collected for proteomics analysis. RESULTS: Dietary XOS/AXRF supplementation improved feed efficiency (P < 0.05) from d 1 to 42 compared to the control group. Proteomic analysis was used to understand the mechanism of improved efficiency uncovering 346 differentially abundant proteins (DAP) (Padj < 0.00001) in supplemented chickens compared to the non-supplemented group. In the jejunum, the DAP translated into decreased ATP production indicating lower energy expenditure by the tissue (e.g., inhibition of glycolysis and tricarboxylic acid cycle pathways). In addition, DAP were associated with decreased epithelial cell differentiation, and migration by reducing the actin polymerization pathway. Putting the two main pathways together, XOS/AXRF supplementation may decrease around 19% the energy required for the maintenance of the gastrointestinal tract. CONCLUSIONS: Dietary XOS/AXRF supplementation improved growth efficiency by reducing epithelial cell migration and differentiation (hence, turnover), actin polymerization, and consequently energy requirement for maintenance of the jejunum of broiler chickens.

Carvacrol in ovo delivery optimization and flow dynamics in broiler chicken eggs.

In ovo delivery of carvacrol, the primary active compound in oregano essential oil (OEO) has the potential to enhance gut development in broilers. This study aimed to optimize in ovo application of OEO by investigating day and site of injection and delivery of carvacrol to different embryonic tissues. In Experiment 1, 2 d of injection (embryonic day (E) 12 or 17.5) and 3 sites of injection for OEO (air cell, amniotic fluid, or yolk) were evaluated based on hatchability and posthatching performance. Experiment 2 aimed to examine the impact of combining OEO with the nonionic surfactant polysorbate 80 (p80) at ratios to carvacrol of 0:0, 0:1, 0.5:1, and 1:1 on carvacrol concentration in amniotic fluid, blood, and yolk. The concentration of carvacrol was measured at 3, 6, and 9 h after OEO injection either without (0:1) or with (1:1) p80. Injection of OEO on E12 led to a significant lower hatchability compared to E17.5 (P ≤ 0.01; Δ = 9.2%). Injecting OEO into the air cell, amniotic fluid, or yolk at E17.5 did not significantly affect hatchability and posthatching performance. The highest concentrations of carvacrol found in egg tissues were observed when injected together with surfactant at the 1:1 ratio (P ≤ 0.001; 14.45 µM, 16.64 µM, and 124.82 µM, for air cell, amniotic fluid, and yolk, respectively) compared to the 0:0, 0:1 or 0.5:1 ratios. Carvacrol was highest in the amniotic fluid and blood at the first time point (3 h postinjection) and decreased afterward (P ≤ 0.001), whereas the concentration in yolk remained elevated up to 9 h postinjection. In conclusion, the optimization of the in ovo delivery of carvacrol resulted in that early injection (E12) had negative effects on hatchability and should be avoided. The findings also suggest that using a nonionic surfactant was crucial for an effective delivery of carvacrol in ovo and the migration from amniotic fluid to yolk within 3 h. In addition, carvacrol's persistence in yolk may serve as a route for delivery into the gastrointestinal tract via the yolk stalk during the peri-hatching phase, potentially influencing gut development.

In ovo delivery of oregano essential oil activated xenobiotic detoxification and lipid metabolism at hatch in broiler chickens.

In ovo interventions are used to improve embryonic development and robustness of chicks. The objective of this study was to identify the optimal dose for in ovo delivery of oregano essential oil (OEO), and to investigate metabolic impacts. Broiler chickens Ross 308 fertile eggs were injected with 7 levels of OEO (0, 5, 10, 20, 30, 40, and 50 µL) into the amniotic fluid at embryonic d 17.5 (E17.5) (n = 48). Chick quality was measured by navel score (P < 0.05) and/or hatchability rates (P < 0.01) were significantly decreased at doses at or above 10 or 20 µL/egg, respectively, indicating potential toxicity. However, no effects were observed at the 5 µL/egg, suggesting that compensatory mechanisms were effective to maintain homeostasis in the developing embryo. To pursue a better understanding of these mechanisms, transcriptomic analyses of the jejunum were performed comparing the control injected with saline and the group injected with 5 µL of OEO. The transcriptomic analyses identified that 167 genes were upregulated and 90 were downregulated in the 5 µL OEO compared to the control group injected with saline (P < 0.01). Functional analyses of the differentially expressed genes (DEG) showed that metabolic pathways related to the epoxygenase cytochrome P450 pathway associated with xenobiotic catabolic processes were significantly upregulated (P < 0.05). In addition, long-chain fatty acid metabolism associated with ATP binding transporters was also upregulated in the OEO treated group (P < 0.05). The results indicated that low doses of OEO in ovo have the potential to increase lipid metabolism in late stages (E17.5) of embryonic development. In conclusion, in ovo delivery of 5 µL OEO did not show any negative impact on hatchability and chick quality. OEO elevated expression of key enzymes and receptors involved in detoxification pathways and lipid metabolism in the jejunum of hatchling broiler chicks.

The Expression of Amino Acid and Fatty Acid Receptors Show an Age-Dependent Pattern Involving Oral Cavity, Jejunum and Lower Gut Sensing in Broiler Chickens.

This work aimed to evaluate the gene expression of amino acids (AA) and fatty acids (FA) sensors in the gastrointestinal tract (GIT) of chickens at two different ages (7 and 26 days post-hatch). Sixteen broilers (Ross 308) were selected, and ten sections of the GIT, including upper (tongue base, upper palate, crop, proventriculus), middle (gizzard, duodenum, jejunum, ileum), and lower GIT section (cecum, colon) were collected for analysis. Relative gene expression of AA (T1R1, T1R3, mGluR1, mGluR4, CaSR, GPR139, GPRC6A, GPR92) and FA (FFAR2, FFAR3, FFAR4) sensors were assessed using qPCR. The statistical model included age, GIT section, and gene. In addition, the correlations between gene expressions were calculated. At day 7, a significantly (p = 0.004) higher expression of AA sensors in the oral cavity and FA sensors in the lower GIT section (i.e., cecum and colon) compared to the middle section was recorded. A higher expression of AA compared to FA sensors was detected at the upper GIT section in 7 (p < 0.001) and 26-day-old chickens (p = 0.026). Thus, at day 7, AA sensors were predominantly (p < 0.05) expressed in the upper GIT section (mainly oral cavity), while FA sensors were mainly expressed in the lower GIT section, at cecum (FFR2 and 4) or colon (FFAR3). These results may indicate that in early life, both ends of the GIT are fundamental for feed intake (oral cavity) and development of the microbiota (cecum and colon). In contrast, at 26 days of age, the results showed the emergence of both AA and FA sensors in the jejunum, presumably indicating the essential role of the jejunum in the digestion absorption of nutrients and the signaling to the brain (gut-brain axis) through the enteroendocrine system. Significant positive correlations were observed between T1R1 and T1R3 (r = 0.85, p < 0.001), CaSR and T1R1 (r = 0.78, p < 0.001), CaSR and T1R3 (r = 0.45, p < 0.050), and mGluR1 and FFAR3 (r = 0.46, p < 0.050). It is concluded that the gene expression is greater in the oral cavity for AA sensors and the lower gut for FA sensors. On day 26, the role of jejunum regarding nutrient sensing is highlighted.

The avian taste system.

Taste or gustation is the sense evolving from the chemo-sensory system present in the oral cavity of avian species, which evolved to evaluate the nutritional value of foods by detecting relevant compounds including amino acids and peptides, carbohydrates, lipids, calcium, salts, and toxic or anti-nutritional compounds. In birds compared to mammals, due to the relatively low retention time of food in the oral cavity, the lack of taste papillae in the tongue, and an extremely limited secretion of saliva, the relevance of the avian taste system has been historically undermined. However, in recent years, novel data has emerged, facilitated partially by the advent of the genomic era, evidencing that the taste system is as crucial to avian species as is to mammals. Despite many similarities, there are also fundamental differences between avian and mammalian taste systems in terms of anatomy, distribution of taste buds, and the nature and molecular structure of taste receptors. Generally, birds have smaller oral cavities and a lower number of taste buds compared to mammals, and their distribution in the oral cavity appears to follow the swallowing pattern of foods. In addition, differences between bird species in the size, structure and distribution of taste buds seem to be associated with diet type and other ecological adaptations. Birds also seem to have a smaller repertoire of bitter taste receptors (T2Rs) and lack some taste receptors such as the T1R2 involved in sweet taste perception. This has opened new areas of research focusing on taste perception mechanisms independent of GPCR taste receptors and the discovery of evolutionary shifts in the molecular function of taste receptors adapting to ecological niches in birds. For example, recent discoveries have shown that the amino acid taste receptor dimer T1R1-T1R3 have mutated to sense simple sugars in almost half of the living bird species, or SGLT1 has been proposed as a part of a T1R2-independent sweet taste sensing in chicken. The aim of this review is to present the scientific data known to date related to the avian taste system across species and its impact on dietary choices including domestic and wild species.

Alanine-specific appetite in slow growing chickens is associated with impaired glucose transport and TCA cycle.

BACKGROUND: The rate of protein accretion and growth affect amino acid requirements in young animals. Differences in amino acid metabolism contribute to individual variations in growth rate. This study aimed at determining how amino acid needs may change with growth rates in broiler chickens. Experiment 1 consisted of testing amino acid choices in two chicken groups with extreme growth rates (the slowest -SG- or fastest -FG- growing birds in a flock). Essential (EAA) (methionine, lysine and threonine) or non-essential (NEAA) (alanine, aspartic acid and asparagine) amino acids were added to a standard control feed (13.2 MJ/kg; 21.6% crude protein). The chickens were offered simultaneous access to the control feed and a feed supplemented with one of the two amino acid mixes added at 73% above standard dietary levels. Experiment 2 consisted of the selection of the bottom 5 SG and top 5 FG chickens from a flock of 580 to study differences in amino acid metabolism using the proventriculus representing gut sensing mechanism. In this experiment, transcriptomic, proteomic, and genomic analyses were used to compare the two groups of chickens. RESULTS: SG preferred NEAA, while they rejected EAA supplemented feeds (P < 0.05). However, FG rejected NEAA (P < 0.05), and they were indifferent to EAA supplemented feed (P > 0.05). Transcriptomic and proteomic analyses identified 909 differentially expressed genes and 146 differentially abundant proteins associated with differences in growth rate (P < 0.05). The integration of gene expression and protein abundance patterns showed the downregulation of sensing and transport of alanine and glucose associated with increased alanine catabolism to pyruvate in SG chickens. CONCLUSION: Dietary preferences for NEAA in the SG group are associated with a potential cytosolic depletion of alanine following an upregulation of the catabolism into TCA cycle intermediates.

The Efficiency of Probiotics Administrated via Different Routes and Doses in Enhancing Production Performance, Meat Quality, Gut Morphology, and Microbial Profile of Broiler Chickens.

To study the efficiency of Bacillus spp. probiotics administered via different routes and doses, a 6-week grow-out trial was conducted using a total of 378 day-old mixed-sex ROSS308 broiler chickens in a completely randomized block design. Six experimental diets included probiotics added at two different inclusion rates into the feed (250 g/ton; PRO250, or 500 g/ton; PRO500), or in the drinking water (25 g/L; PRO-WS), or as a feed synbiotic (250 g probiotic + 250 g/ton prebiotic; SYN), compared to a negative (NC; without additives) and positive control (PC; with antibiotics) diets. The PRO-WS enhanced feed intake (p < 0.05) and tended to improve average daily gain and final body weight (p = 0.14). Broiler gut morphology in the duodenum including the villus height (p = 0.04), villus width (p = 0.05) and crypt depth (p = 0.02) were improved by PRO500. Firmicutes was the most abundant phylum, followed by Bacteroidetes. Streptococcaceae, Lachnoospiraceae, Peptostreptococcaceae, Ruminococcaceae, and Erysipe-lotrichaceae were the top five most abundant families. Antibiotic inclusion in PC reduced microbial beta-diversity and increased similarity compared to probiotic inclusion (p = 0.05). Probiotic inclusion reduced the relative abundance of Bacteroides fragilis, which is a commonly isolated pathogen and is considered as a marker for antimicrobial resistance. Overall, probiotic supplementation via feed or water may potentially improve the production performance of the broiler chickens, and water-soluble probiotics are potentially more effective. Probiotics, especially when added to water, suggest a promising feed additive to support gut microbial maturation and diversity, and may reduce resistant bacteria in broiler chickens. However, it is suggested that the best route for the administration of probiotics be further examined under commercial conditions to find the most effective and practical application method that yields the most consistent results.

Cinnamaldehyde Induces Release of Cholecystokinin and Glucagon-Like Peptide 1 by Interacting with Transient Receptor Potential Ankyrin 1 in a Porcine Ex-Vivo Intestinal Segment Model.

Cinnamaldehyde and capsaicin have been reported to exert effects on the gastric function, mediated by the interaction with transient receptor potential ankyrin channel 1 (TRPA1) and transient receptor potential vanilloid channel 1 (TRPV1), respectively. This study examined whether these compounds could trigger the release of cholecystokinin (CCK) and/or glucagon-like peptide 1 (GLP-1) in the pig's gut in a porcine ex-vivo intestinal segment model. Furthermore, it was verified whether this response was mediated by TRPA1 or TRPV1 by using the channel's antagonist. These gut peptides play a key role in the "intestinal brake", a feedback mechanism that influences the function of proximal parts of the gut. Structural analogues of cinnamaldehyde were screened as well, to explore structure-dependent activation. Results showed a significant effect of capsaicin on GLP-1 release in the proximal small intestine, TRPV1 independent. TRPA1 showed to be strongly activated by cinnamaldehyde, both in proximal and distal small intestine, evidenced by the release of CCK and GLP-1, respectively. Out of all structural derivates, cinnamaldehyde showed the highest affinity for TRPA1, which elucidates the importance of the α,ß-unsaturated aldehyde moiety. In conclusion, cinnamaldehyde as a TRPA1 agonist, is a promising candidate to modulate gastric function, by activating intestinal brake mechanisms.

Nutrient sensing, taste and feed intake in avian species.

The anatomical structure and function of beaks, bills and tongue together with the mechanics of deglutition in birds have contributed to the development of a taste system denuded of macrostructures visible to the human naked eye. Studies in chickens and other birds have revealed that the avian taste system consists of taste buds not clustered in papillae and located mainly (60 %) in the upper palate hidden in the crevasses of the salivary ducts. That explains the long delay in the understanding of the avian taste system. However, recent studies reported 767 taste buds in the oral cavity of the chicken. Chickens appear to have an acute sense of taste allowing for the discrimination of dietary amino acids, fatty acids, sugars, quinine, Ca and salt among others. However, chickens and other birds have small repertoires of bitter taste receptors (T2R) and are missing the T1R2 (related to sweet taste in mammals). Thus, T1R2-independent mechanisms of glucose sensing might be particularly relevant in chickens. The chicken umami receptor (T1R1/T1R3) responds to amino acids such as alanine and serine (known to stimulate the umami receptor in rodents and fish). Recently, the avian nutrient chemosensory system has been found in the gastrointestinal tract and hypothalamus related to the enteroendocrine system which mediates the gut-brain dialogue relevant to the control of feed intake. Overall, the understanding of the avian taste system provides novel and robust tools to improve avian nutrition.

Estimation of genetic parameters for body weight and egg production traits in Mazandaran native chicken.

Native chicken breeding station of Mazandaran was established in 1988 with two main objectives: genetic improvement through selection programs and dissemination of indigenous Mazandarani birds. (Co)variance components and genetic parameters for economically important traits were estimated using (bi) univariate animal models with ASREML procedure in Mazandarani native chicken. The data were from 18 generations of selection (1988-2009). Heritability estimates for body weight at different ages [at hatch (bw1), 8 (bw8), 12 (bw12) weeks of ages and sex maturation (wsm)] ranged from 0.24 ± 0.00 to 0.47 ± 0.01. Heritability for reproductive traits including age at sex maturation (asm); egg number (en); weight of first egg (ew1); average egg weight at 28 (ew28), 30 (ew30), and 32 (ew32) weeks of age; their averages (av); average egg weight for the first 12 weeks of production (ew12); egg mass (em); and egg intensity (eint) varied from 0.16 ± 0.01 to 0.43 ± 0.01. Generally, the magnitudes of heritability for the investigated traits were moderate. However, egg production traits showed smaller heritability compared with growth traits. Genetic correlations among egg weight at different ages were mostly higher than 0.8. On the one hand, body weight at different ages showed positive and relatively moderate genetic correlations with egg weight traits (ew1, ew28, ew30, ew32, ew12, and av) and varied from 0.30 ± 0.03 to 0.59 ± 0.02. On the other hand, low negative genetic correlations were obtained between body weight traits (bw1, bw8, bw12, and wsm) and egg number (en). Also, there is low negative genetic correlation (-24 ± 0.04 to -29 ± 0.05) between egg number and egg weight. Therefore, during simultaneous selection process for both growth and egg production traits, probable reduction in egg production due to low reduction in egg number may be compensated by increases in egg weight.