Selenium (Se) is an essential element in poultry nutrition and its bio-efficacy depends on its chemical form. A growing body of research proves that organic forms of Se, mainly selenomethionine (SeMet), in poultry diets have a range of important advantages over traditional sodium selenite. In fact, the organic Se concept considers SeMet as a storage form of Se in the chicken body. As chickens are not able to synthesize SeMet, its provision through diet is a key strategy to fight commercially relevant stresses. Indeed, in stress conditions, when increased selenoprotein expression requires additional Se, while its provision via feed usually decreases due to a reduction in feed consumption, Se reserves in the body (mainly in the muscles) could help maintain an effective antioxidant defense and prevent detrimental consequences of stresses. The poultry industry is looking for the most effective sources of organic Se for commercial use. In this review, advantages and disadvantages of main organic Se sources for poultry (Se-yeast, SeMet, and OH-SeMet) are analyzed, and future directions for the development of new Se sources are identified.

The selection of rapidly growing animals in breeding programs has had inadvertent detrimental effects on meat quality. Thus, the aim of the present study was to investigate the relationship between body weight (BW) and meat quality traits, and the effects of genes encoding insulin-like growth factor I (IGF-I), insulin-like growth factor II (IGF-II), melanocortin-4 receptor (MC4R), and calpain 1 (CAPN1) on BW, carcass yield, and meat quality of the Thai indigenous chicken, Leung Hang Khao. Five hundred and ten chickens were used for genotyping. PCR-restriction fragment length polymorphism and PCR-single strand conformation polymorphism were used to determine the genotypes of IGF-I, IGF-II, MC4R, and CAPN1. BWs were collected from 0–16 weeks of age. The chickens were sacrificed at 16 weeks and individual carcass yields and meat qualities (drip loss, cooking loss, and shear force) were recorded. The correlations between BW and meat qualities were determined. Significant correlation between BW and cooking loss and shear force of breast meat and between BW and drip loss of thigh meat were detected (P<0.05); however, the magnitude of the association was low (−0.1–0.1). IGF-I was eliminated from the association analysis because genotype AA was lost and the frequency of occurrence of the AC genotype was low (0.04). Significant associations between IGF-II, CAPN1, and BW, and CAPN1 and meat quality were detected, while non-significant association between MC4R and BW was observed. The results indicated a low, negative relationship between BW and meat quality, and that the IGF-II and CAPN1 could be used as genetic markers in Leung Hang Khao chickens to improve growth and meat quality through breeding.

This study evaluated the interaction effect of maternal and progeny vitamin regimens on the performance of ducklings. At 38 weeks of age, 780 female and 156 male duck breeders were fed either regular or high vitamin premix diet (maternal high premix had higher levels of all vitamins except K₃ than maternal regular premix) for 16 weeks. Ducklings hatched from eggs laid at the end of the duck breeder trial were kept separate according to maternal treatment and were fed 2 levels of vitamin premix (NRC and high, progeny high premix had higher levels of all vitamins except biotin than progeny NRC premix) for 35 days. Body weight (P<0.001) and tibia ash (P=0.033) of 1-day-old ducklings and serum total superoxide dismutase activity of 14-day-old ducklings (P=0.027) were increased by maternal high vitamin premix. Progeny high vitamin premix increased body weight (14 days, P=0.019; 35 days, P=0.034), body weight gain (1–14 days, P=0.021; 1–35 days, P=0.034), gain:feed ratio (1–14 days, P<0.001), feed intake (15–35 days, P=0.037), serum total antioxidant capacity (14 days, P=0.048; 35 days, P=0.047), and serum calcium (14 days, P=0.007), and decreased serum malondialdehyde (14 days, P=0.038; 35 days, P=0.031) of ducklings. Maternal vitamin premix–progeny vitamin premix interaction significantly affected body weight (14 days, P=0.029), body weight gain (1–14 days, P=0.029), and feed intake (1–14 days, P=0.018) of progeny ducklings. Briefly, progeny NRC premix decreased the growth performance (days 1–14) of ducklings from maternal regular vitamin group, but not duckling from maternal high vitamin group. The results demonstrate a shortcoming of current vitamin recommendations for ducklings and suggest that the vitamin needs of starter ducklings can be met by either maternal or progeny vitamin supplementation.

The aims of the present study were to investigate the growth performance of ducks fed diets with different types of Sipjeondaebo-tang (ST) byproduct meal and red ginseng marc with fermented red koji (RGMK), and to investigate ammonia (NH₃) fluxes from duck litter treated with alum or aluminum chloride (AlCl₃). A total of 270 1-d-old ducks (180 males and 90 females) were allotted in a completely randomized design with 6 treatments and 3 replicates of 15 birds per pen. The six diet treatments were: basal diet, pelleted 1% ST byproduct powder, pelleted 1% RGMK, 1% blends (a mixture of ST byproduct and RGMK) powder, 1% pelleted blends, and coated pellets of 1% blends. The six litter treatments with 6 diet treatments were: no treatment, 50, 100, or 200 g alum/kg duck litter, and 100 g or 200 g AlCl3/kg duck litter (treatments T1, T2, T3, T4, and T5, respectively). During days 10 to 40, ducks fed the 5 experimental diets had significantly different (p<0.05) weight gains and feed conversion ratios compared with those fed the control diet, but initial body weight, final body weight, feed intake, and mortality were not affected. There were significant differences (p<0.05) in NH₃ fluxes among treatments over the 6 weeks of the study, except for week 0. The relative NH₃ losses at week 6 were lower by 25.6, 45.3, 45.6, 46.7, and 48.6% than those in the controls in T1, T2, T3, T4, and T5 respectively. In conclusion, feeding pellets or coated pellets of ST and RGMK and using alum or AlCl₃ in the litter at the same time improves weight gain and feed conversion ratio performance and reduces mortality and NH₃ losses in ducks.

Tryptophan, an essential amino acid, is enzymatically metabolized to two compounds, kynurenine and serotonin, and 95% of tryptophan is metabolized to kynurenine. As chickens have hyperglycemia and high temperature, tryptophan glycation occurs more easily in chickens than in mammals. Part of tryptophan is non-enzymatically converted to two types of glycated tryptophan, tryptophan-Amadori product and (1R, 3S)-1-(d-gluco-1, 2, 3, 4, 5-pentahydroxypentyl)-1,2,3,4-tetrahydro-β-carboline-3-carboxylic acid (PHP-THβC). Although these compounds are detected in the plasma of chickens, information on the half-life of PHP-THβC in the blood circulation is limited. Therefore, the present study aimed to measure the half-life of plasma PHP-THβC in chickens. PHP-THβC (114 nmol/0.2 mL/70 g body weight) was intravenously administered to chickens via the wing vein, and blood samples were collected at 0, 15, 30, 60, 180, 360, 720, and 1440 min after administration. Plasma concentrations of PHP-THβC were measured by liquid chromatography-mass spectrometry. Plasma PHP-THβC reached to a peak concentration of 16.1 βM at 30 min after administration, and then decreased rapidly to return to the physiological level (0 min) at 360 min after administration. The half-life of plasma PHP-THβC was calculated by non-linear regression analysis, and it was found to be 107 min. This study was the first to measure plasma half-life of glycated tryptophan.

Heat stress hampers egg production and lowers fertility in layers. This study investigated global protein abundance in the small yellow follicles (SYFs, 6–8 mm diameter) of a broiler-type strain of Taiwan country chickens (TCCs) under acute heat stress. Twelve 30-week-old TCC hens were allocated to a control group maintained at 25°C, and to three acute heat-stressed groups subjected to 38°C for 2 h without recovery, with 2-h recovery, or with 6-h recovery. Two-dimensional difference gel electrophoresis analysis identified 119 significantly differentially expressed proteins after acute heat exposure. Gene ontology analysis revealed that most of these proteins are involved in molecular binding (34%), catalytic activity (23%), and structural molecule activity (11%), and participate in metabolic processes (20%), cellular processes (20%), and cellular component organization or biogenesis (11%). Proteins associated with stress response and survival (HSP25, HSP47, HSP70, HSC70, HSPA9), cytoskeleton remodeling, mitochondrial metabolic process of ATP production, antioxidative defense (peroxiredoxin-6), cargo lipid export and delivery (vitellogenin, apolipoprotein B and A1), and toxin/metabolite clearance and delivery (albumin) were upregulated after acute heat stress in the SYFs of TCCs. No overt cell death and atresia were observed in SYFs after acute heat stress. Collectively, these responses may represent a protective mechanism to maintain follicle cell integrity and survival, thereby ensuring a sufficient pool of SYFs for selection into the ovulation hierarchy for successful egg production.

Recent studies have suggested that a high-fructose diet leads to the development of metabolic syndrome in mammals. However, relatively little information is available regarding the absorption of fructose in the chicken intestine. We therefore investigated fructose absorption and its transporters in the chicken small intestine. The gene expression of three transporters (glucose transporter protein member 2 and 5 and sodium-dependent glucose transporter protein 1) in the jejunum of fasted chicks were lower than those in chicks fed ad libitum. The everted intestinal sacs (in vitro method for investigating intestinal absorption) showed that the concentration of fructose uptake rapidly increased within 15 min after incubation, and then gradually increased until 60 min. After 15 min of incubation, fructose uptake in the ad libitum chick intestine was approximately 2-fold that in the fasted intestine and was less than half of the glucose uptake in the ad libitum chick intestine. Our results suggest that fructose is absorbed in the small intestine of chicks and that uptake is decreased by fasting treatment with decreases in the mRNA expression of related transporters.

This study determined the effects of pro-inflammatory cytokines (interleukin (IL)-1β and IL-6) on the expression of eggshell mineralization-related ion transporters in the hen uterus mucosa. Uterine mucosal tissues collected from White Leghorn laying hens were cultured for 1.5 or 3 h in TCM-199 medium with or without 100 ng/mL recombinant chicken IL-1β or IL-6. Total RNA and protein were extracted from the cultured tissues for real-time polymerase chain reaction (PCR) and western blot analyses and some tissues were processed into paraffin sections for immunostaining with calcium-binding protein D28K (CaBP-D28K) antibody. The gene expression of CaBP-D28K, PMCA1, PMCA2 (plasma membrane calcium-transporting ATPase 1 and 2; calcium pumps), CA2 (carbonic anhydrase 2), and SLC26A9 (solute carrier family 26 member 9; HCO₃⁻ transporter) was analyzed by real-time PCR and protein density of CaBP-D28K by western blotting. Expression of CaBP-D28K, PMCA1, PMCA2, CA2, and SLC26A9 was significantly higher in the tissues treated with IL-1β and IL-6 than in the control group at 1.5 h of incubation. Immunoreactive CaBP-D28K was localized in the uterine tubular gland cells in all groups, but its level was significantly lower in the tissues incubated for 1.5 h with IL-1β and IL-6 than in the control group. No significant differences were observed in the expression of all tested genes and CaBP-D28k content between the cytokine-treated and control groups at 3 h of incubation. These results suggest that IL-1β and IL-6 may not suppress the expression of genes related to Ca²⁺ and HCO3⁻ transportation for eggshell formation, while CaBP-D28K protein content in uterine glandular cells was reduced by these cytokines during the early exposure phase. Thus, IL-1β and IL-6 induced by infections may disrupt the transportation of Ca²⁺ for eggshell formation through decreased CaBP-D28K content in the uterus.

Prolactin (PRL) is a hormone mainly secreted by the anterior pituitary gland. In birds, PRL exerts a variety of physiological functions in target tissues expressing the PRL receptor (PRLR). In chicken, the PRLR mRNA is abundant in the anterior pituitary gland, but its regional and cellular localization are unknown. In the present study, we investigated the expression of the PRLR mRNA in cephalic and caudal lobes of the chicken anterior pituitary gland. Real-time polymerase chain reaction (PCR) revealed high levels of PRLR mRNA in both cephalic and caudal lobes. In situ hybridization revealed that the PRLR mRNA was distributed in a wide area of both lobes, and co-localized with the PRL and growth hormone (GH) mRNAs in the cephalic and caudal lobes, respectively. These results suggest that PRL exerts autocrine/paracrine effects through PRLR on PRL-producing lactotrophs and GH-producing somatotrophs in the chicken anterior pituitary gland.

Varying amounts of phytosterols (PS) occur naturally in several foods of plant origin. PS, which are structurally and functionally similar to cholesterol, have been shown to reduce plasma total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels. Moreover, PS disrupts endocrine function in certain animals. In the present study, we investigated the effects of high doses of PS on adrenal and reproductive endocrine function during sexual maturation in Japanese male quails. Two experiments were conducted; in the first experiment, quail chicks were subjected to long-term chronic feeding of PS (8, 80, and 800 mg/kg body weight [BW]) and the chemicals were gavaged into the crop sac from 7–50 days post-hatching. From the forty-fourth day, half of the animals in each group were subjected to a 6-day adrenocorticotropic hormone (ACTH) challenge for artificial stimulation of the adrenal gland and evaluation of long-term PS effects; in the second experiment, single doses of PS were subcutaneously injected (SC) into adult males (10-weeks-old) to assess the acute direct effect. Results indicated that chronically PS-fed animals showed a better adrenal response to ACTH challenge, and the corticosterone levels were higher (P<0.05) than those of the controls. Moreover, corticosterone levels were also high (P<0.05) 3 h after SC injection of PS. In contrast, testosterone levels and the testes weights were significantly lower (P<0.05) in the groups chronically administered with PS. No differences were observed in the testosterone levels in the acute experiment or luteinizing hormone (LH) levels in either experiment. In conclusion, the differential effects of PS on the adrenal gland and testis might be due to preferential use of different lipoprotein-cholesterol forms for steroid production. In addition, PS might locally perturb testosterone production by its accumulation or delay in testicular maturation.