In avian species, maternal IgY transferred across egg yolks from mother to offspring plays a key role to protect the hatching chicks against pathogenic attacks. The process of avian maternal IgY transfer is divided into two steps: the first step is the transfer from the maternal circulation to the egg yolks of developing oocytes in the maternal body, and the second step is the transfer from the egg yolks to the embryonic circulation in the developing eggs. The second step relies on IgY-Fc receptor, FcRY, expressing on the yolk sac membrane. However, in the first step, the molecular basis of IgY transfer is still unknown. This review focused on the structural requirements of IgY and heterologous immunoglobulin such as human IgG for transferring into egg yolks of birds, and a plausible molecular mechanism for immunoglobulin uptake in ovarian follicles were discussed. Recent research revealed existence of a selective IgY transfer system that recognizes Cυ3/Cυ4 interface of IgY in ovarian follicles of birds.
Pigeons (Columba livia) have long history of selective breeding for many purposes; one of them is pigeon racing using their homing ability. A total of 221 pigeon samples were sequenced for lactate dehydrogenase-A gene (LDH-A) including part of exon 5 and part of exon 6 and intervening intron 5. Six polymorphic sites were identified in intron 5; one indel and five SNPs. Statistical significant differences in allele frequencies were observed for 595bp and 600bp alleles between homing and non-homing groups in both Japanese and Egyptian pigeons. The frequency of 600bp allele was higher in both Japanese and Egyptian homing than in non-homing pigeons (P<0.0001). In Japanese pigeons; significant difference in allele frequency of three SNPs was observed between homing and non-homing groups, while in Egyptian pigeons, although similar tendency was observed, the difference in allele frequency was not significant. The DNA polymorphisms of pigeon LDH-A gene can be a potential genetic marker for homing ability in racing pigeon breeding.
Meat color traits have economic importance and are regulated by multiple genetic loci (quantitative trait loci: QTLs), environmental factors, and their interactions. Using an F2 intercross population between the Oh-Shamo (Japanese Large Game) and White Leghorn chickens, QTL analysis based on the Bayesian model was performed for meat color traits. A total of 280 F2 individuals at 20 weeks of age were genotyped for 88 microsatellite markers covering 21 autosomes. As a result, nine QTLs (two on chromosome 1, two on chromosome 2, and one each on chromosomes 3, 7, 9, 17, and 24) were detected for L* (lightness), a* (redness), and b* (yellowness) values in the breast and thigh muscles. Some QTLs had a single genetic effect only on a meat color trait, however some QTLs exhibited plural genetic effects on the same and/or different traits. For example, the chromosome 3 QTL for the b* value in the raw breast muscle had main, sex-specific, and epistatic-interaction effects on the same trait, and furthermore it had an epistatic effect on a different trait (L* value in the minced thigh muscle). The chromosome 7 QTL had a sex-specific effect on the a* value in raw breast muscle and also had an epistatic effect on a different trait (b* value in the minced thigh muscle). These results clearly indicated that the genetic control of meat color is complex. In addition, this is the first report of QTL mapping focused on the epistatic interaction for meat color traits in chickens.
We have previously reported the association between chicken cholecystokinin type A receptor gene (CCKAR) haplotypes and growth traits in an F2 resource population produced by crossing low- and high-growth lines of the Hinai-dori breed. The high-growth line was developed from a low-growth founder from the Preservation Society of the Hinai-dori breed by long-term selection for growth performance at the Akita Prefectural Livestock Experiment Station. In the present study, we determined the effect of a single-nucleotide polymorphism (SNP, AB604331: g.420 C>A) in the 5′-untranslated region of CCKAR on the growth traits of the F2 population. A mismatch amplification mutation polymerase chain reaction assay was developed to distinguish between the 3 genotypes (A/A, A/C, and C/C) in the F2 population, and the effect of the SNP on growth traits was estimated. The data showed that body weight at 10 and 14 weeks of age, and average daily gain between 4 and 10 weeks, 10 and 14 weeks, and 0 and 14 weeks of age in individuals with the A allele was superior to that in those with the C allele. The electrophoretic mobility shift assay was performed to clarify the contribution of the g. 420 C>A SNP in the predicted YY1 binding site. As a result, the YY1 protein showed a stronger binding affinity for g.420 A probe, suggesting the possibility that the SNP affects transcriptional efficiency of the CCKAR. The A allele frequencies in the high- and low-growth lines maintained in fiscal year 2010 were 0.889 and 0.124, respectively. The difference in the allele frequencies of these lines is thought to be caused by long-term selection for growth performance since the probability was too significantly (P<0.01) low to be caused by random genetic drift.
Ketone bodies such as β-hydroxybutyrate and acetoacetate have physiological functions in addition to being used as an energy source. In order to assess the effect of elevated ketogenesis on blood lipid profiles and redox status, a ketogenic diet (KD), a high-fat, low-carbohydrate, and low-protein diet, was fed to chicken for 4 weeks. Plasma β-hydroxybutyrate, but not acetoacetate, concentrations were significantly increased by KD feeding for 2 and 4 weeks. The KD also induced elevation of plasma non-esterified fatty acid (NEFA) and total cholesterol concentrations, whereas plasma triglyceride concentration was decreased. Plasma total antioxidant activity in chicken with ketosis induced by KD was lower than that of the control. However, the level of plasma TBARs, an oxidative stress marker, was also reduced by KD feeding. A reduction of energy intake was observed in chickens fed the KD; therefore, the effect of a restricted diet (RD) was also investigated. Plasma β-hydroxybutyrate concentration, lipid (total cholesterol and NEFA) concentration, and redox status were not affected by RD feeding. These data suggest that a high-fat, low-carbohydrate, and low-protein diet induces ketosis by elevating blood β-hydroxybutyrate concentration in chicken. Under conditions of ketosis induced by the KD, total antioxidant capacity was reduced along with a modulation of the blood lipid profile in chicken.
The experiment was conducted to investigate the effect of dietary supplementation with different level of supercritical CO2 extraction of Schisandra Chinensis (SCESC) (0.1%, 0.2%, and 0.4%) on antioxidant status and meat quality of broilers. The results showed that the total superoxide dismutase (T-SOD) activity in heart and liver was increased significantly by supplementing with SCESC in the diet of birds, the malonaldehyde (MDA) concentration in heart of birds was lower in the SCESC group than the control, and the glutathion reductase (GR) activity in liver and kidney of the birds was increased significantly. There was a significant reduction of the abdominal fat in the experimental group. The drip loss of breast meat was significantly decreased through supplementing with SCESC in the diet of birds. The pH was higher in the 0.1% SCESC group than the control. The shear force of breast meat from broilers was decreased by 0.2% SCESC supplementation. Compared to the control, the content of crude fat of breast meat from broilers was increased significantly. At the same time, diets supplemented with 0.2% SCESC increased the crude protein content of breast meats. Furthermore, diets supplemented with 0.4% SCESC had an increased Inosinic Acid (IMP) content significantly. On the basis of these observations, we concluded that diets supplemented with SCESC improved antioxidant enzyme activity of tissues and improved meat tenderness and nutritional value of breast and thigh meat.
This trial was conducted to evaluate the effects of high-dose daidzein supplements on laying performance, egg quality and antioxidation in laying hens during the late laying period. Seven hundred sixty eight 55-wk-old Hyline Brown were randomly assigned to four groups with 8 replicates of 24 birds each (192 laying hens per group) and fed diets supplemented with 0 (control), 10 mg/kg, 50 mg/kg and 100 mg/kg daidzein for 8 wk in the diets. Egg production, egg mass, feed conversion and egg yolk malondialdehyde were significantly effected by daidzein supplementation (P<0.05), while there are significant quadratic correlations between average egg production/egg mass/feed conversion/ egg yolk malondialdehyde and daidzein supplementation (quadratic P=0.022, 0.003, 0.021 and 0.002; respectively). The optimal daidzein supplementation in the diet of laying hens during the late laying period for maximum egg production, egg mass, feed conversion and egg yolk malondialdehyde were 72 mg/kg, 48.5 mg/kg and 56.34 mg/kg and 51.43 mg/kg. Daidzein supplementation significantly improved three calcium-related egg quality indexes (eggshell thickness, eggshell percentage and eggshell strength; P<0.05) and egg yolk total superoxide dismutase (P<0.05), linearly. These findings indicated that the daidzein could be a very effective additive to improve laying performance and eggshell quality in the birds during the late laying period, even though the dose of it was high.
This study was conducted to examine the effects of a combined in-feed supplementation of Aspergillus awamori and Saccharomyces cerevisiae on growth and muscle protein metabolism and fatty acid profiles in broilers. Chicks (15 d old) were fed a basal diet as control, diets supplemented with 0.05% A. awamori, 0.10% S. cerevisiae, or a combination of both (7 birds/group) for 12 days. Growth of the birds was promoted by all treatments. Synergistic effects of A. awamori and S. cerevisiae were observed on body weight gain and feed conversion, breast muscle weight, and digestibility of dietary protein. Plasma 3-methylhistidine concentrations were decreased by A. awamori and S. cerevisiae, and synergistically by the combination. Gene expressions of proteolysis-related factors in muscle were reduced by all treatments. Conversely, mRNA expressions of myosin and actin were synergistically increased by the combination. Abdominal fat and plasma triglycerides were decreased by A. awamori and the combination, but not by S. cerevisiae, while muscle fat content was increased by all treatments. Interestingly, there was a decrease in saturated fatty acids and an increase in unsaturated fatty acids in muscle in all treatment groups. This change in fatty acid profile was partially related to mRNA expression of delta-6 fatty acid desaturase in the muscle. In conclusion, the combined supplementation of A. awamori and S. cerevisiae synergistically improves growth performance by promoting muscle protein metabolism. In addition, A. awamori and S. cerevisiae modify the muscle fatty acid profile.
An experiment was conducted to evaluate the effect of dietary supplementation of histidine, β-alanine, blood meal (BM), magnesium oxide (MgO), and their combination on carnosine and anserine concentrations of broiler breast meat. A total of 210 1-d-old broiler chicks were randomly allotted to 3 replicates of 7 dietary treatments: (1) Control diet (C), (2) C+histidine (His), (3) C+β-alanine (β-Ala), (4) C+histidine+β-alanine (His+β-Ala ); (5) C+histidine+β-alanine+MgO (His+β-Ala+MgO), (6) C+5% BM (BM), and (7) C+5% BM+MgO (BM+MgO). Histidine, β-alanine, and MgO were supplemented to diets at 2.9, 3.7, and 4.0 g/kg diet, respectively. The broilers were fed experimental diets for 32 d and the concentrations of carnosine and anserine in breast meat were measured weekly and at 32 d of the age. Results indicated that the concentrations of carnosine, anserine, and their sum in breast meat were increased (linear, P<0.01) with age in all treatments. There were significant differences in carnosine concentrations among treatments in all weeks. At 32 d, all 3 histidine-supplemented treatments (His, His+β-Ala, and His+β-Ala+MgO) and BM+MgO treatment had greater (P<0.05) carnosine concentrations than the control. The anserine concentrations differed (P<0.01) among treatments at 7, 14, and 21 d. The sum of carnosine and anserine concentrations was the greatest for His+β-Ala+MgO treatment, but the least for β-Ala treatment at 21 d. In conclusion, dietary supplementation of histidine alone or with β-alanine may increase carnosine concentrations, but not anserine concentrations of broiler breast meat. Dietary supplementation of additional MgO in diets containing His, β-Ala, and/or BM has little effect on carnosine and anserine concentrations in broiler breast meat.
Toltrazuril is a symmetrical tiazinetrione compound. It is active against all intracellular developmental stages including those of schizogony and gametogony. In this study the disposition kinetics of toltrazuril (TZR) and its major metabolites (TZR-SO and TZR-SO2) in broiler chickens after single oral administrations of 10 or 20 mg/kg were investigated. Mean plasma concentrations of TZR peaked at 16.4 and 25.2 μg/mL at 5.0 and 4.7 h after dosing, respectively. TZR was converted to the short-lived intermediary metabolite toltrazuril sulfoxide (TZR-SO), and then further metabolized to the reactive toltrazuril sulfone (TZR-SO2) being actually more slow eliminated with 80.3 and 82.9 h than TZR (10.6 and 10.7 h) or TZR-SO (14.8 and 15.3 h) in low and high dosing groups, respectively. Prolonged elimination half-life of TZR-SO2 could be interpreted as the persistent clinical efficacy of TZR in the treatment of protozoal parasites infection.
Leptin is an adipocyte-derived hormone involved in the regulation of feeding behavior and energy homeostasis in vertebrates. We recently reported that leptin activates the JAK-STAT signaling pathway through the chicken leptin receptor (chLEPR). However, the molecular inhibitory mechanism by suppressor of cytokine signaling 3 (SOCS3), observed in mammalian leptin signaling, has not been elucidated in avian species. Therefore, the role of chicken SOCS3 (chSOCS3) in signal transduction through the chLEPR was analyzed in this study. Leptin increases SOCS3 mRNA expression in chicken hepatoma cells, LMH, and also activates the chSOCS3 gene promoter in the chLEPR-expressing cells. Overexpression of chSOCS3 inhibited leptin-induced signaling by blocking phosphorylation of JAK2 and subsequent activation of STAT3 similar to that observed in mammals. Signaling inhibited by chSOCS3 was not restored in the chLEPR mutated docking site of SOCS3. In addition, mutation of Phe25 in the kinase inhibitory region of chSOCS3 abolished SOCS3 activity via the wild chLEPR. The present study indicates that SOCS3 is a negative feedback regulator of leptin signaling in chickens as well as in mammals. However, the inhibitory mechanism in chickens may differ slightly from that observed in mammals.
The present study describes ontogenic profile of mRNA expressions of hexokinase (HK; EC 220.127.116.11) and glucokinase (GK; EC 18.104.22.168, otherwise known as HKIV) that catalyze the first step of glucose metabolism by cells. The liver and the skeletal muscle were collected from 11 to 21 day embryos (n=6) of the White Leghorn chicken and the mRNAs of HKI and II, two HKs known in the chicken, and GK were measured by semi-quantitative reverse transcription PCR. In the liver, HKI mRNAs gradually decreased during the experimental period, while GK mRNAs gradually increased. In the skeletal muscle, HKI increased on day 13 and was almost stable thereafter, while GK gradually decreased. HKII expression tended to increase on day 13 and remained stable thereafter in both the organs. These results suggest a possibility that the well-established domination of GK to HK in the liver is gradually acquired during embryogenesis. Whether embryonic skeletal muscle expresses active GK protein should be studied further.
The aim of this study was to determine the effects of probiotics on T cell subsets induction in the intestine of broiler chicks. Day-old male broiler chicks were fed with or without probiotics consisting of Streptococcus faecalis, Clostridium buthricum, Bacillus mesentericus (probiotics group and control group, respectively). Cryostat sections of their ileum, cecum and rectum at day 0, 7 and 14 of feeding were immunostained for CD4, CD8 and TCRγδ, and the frequencies of positive cells in the mucosal tissue were analyzed. The CD4+, CD8+, TCRγδ+ T cells were localized in the lamina propria of intestinal mucosa in all birds. At day 7 and 14, CD8+ T cells were localized also in the mucosal epithelium of all segments in the probiotics group and of cecum in control group, and TCRγδ+ T cells were observed in the mucosal epithelium of all birds. The frequencies of CD4+, CD8+, TCRγδ+ T cells were increased with age from day 0 to day 14 in both control and probiotics groups. The frequency of CD8+ T cells was significantly greater in probiotics group than control group in the ileum and rectum (P<0.05) and the cecum (P<0.01) at day 7. There were no significant differences in the frequency of CD4+ and TCRγδ+ T cells between control and probiotics groups in all intestinal segments at day 7 and 14. The ratio of CD8+/CD4+ T cells was greater than 1.0 in all tissues. The ratio in the ileum at day 7 was significantly greater in the probiotics group than control group (P<0.05). These results further suggest that probiotics cause an influx of the CD8+ T cells into the intestinal mucosa, which may enhance the intestinal immunity by CD8+ T cells in young chicks.