The physiological regulation of energy homeostasis is critical to an animal’s long-term survival and is relevant to the poultry industry in relation to animal production and welfare. In mammals, rapid progress has been made over the past decade in identifying the neural circuitry in the hypothalamus involved in the regulation of energy balance. Two neuronal cell groups in the arcuate nucleus (the avian infundibular nucleus), one of which expresses neuropeptide Y (NPY) and agouti-related protein (AGRP) mRNAs and the other pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) mRNAs are particularly important because their encoded peptides exert potent anabolic (NPY and AGRP) and catabolic (POMC and CART) influences. The expression of these genes is altered in a co-ordinated manner by experimental food deprivation or restriction, and by metabolic hormones such as leptin, insulin and ghrelin, so as to enable energy homeostasis to be maintained in the face of perturbations such as energy shortage. The NPY/AGRP and POMC/CART neurones show striking evolutionary conservation between birds and mammals in their neuroanatomical localization, their behavioural effects, and the regulation of their gene expression by nutritional status. However, orexin/hypocretin and melanin-concentrating hormone (MCH) neuropeptides in the lateral hypothalamic area, that exert anabolic effects on energy homeostasis in mammals, do not appear to fulfil these functions in birds. Collectively these observations provide a neuroanatomical framework in the avian brain for future investigations into the regulation of energy balance in commercially important poultry as well as other avian models.

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Choice feeding has been used to compare likes or dislikes of feedstuff for animals. In the two-choice preference test, it is expected that chicks eat their diets equally from two feeders when they were given the diets with the same palatability. The present experiment was conducted to make sure whether this basic principle is true or not in the short-term choice feeding. When chicks were given the same diet by two feeders, they ate the diet predominantly from one or the other of two feeders for a certain time. Half of chicks ate the diet from right feeders (right-handed chicks) and the other from left feeders (left-handed chicks) so that feed intake from right and left feeders was the same. These results indicated that the favorite feeder position was not confined to one side. Chicks given the choice between diets with the same nutritive value (added with or without 1% cholesterol) did not show the special preference or aversion to cholesterol, and they initially ate the diet from particular feeders, regardless of the presence or absence of cholesterol. Such undesirable feeding behavior in the choice feeding disappeared as the experiment progressed, or by using older chicks or the acclimation to the choice feeding prior to the experiment.

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The aim of this study was to examine the effects of age and gonadal steroids on the localization of T cell subsets in the epididymis of roosters in order to determine the factors affecting their populations. Immature and matured White Leghorn male birds were used, and some of the immature birds were i.m. injected daily with 1mg testosterone propionate (TP), 1mg estradiol benzoate (EB) or 100μl of sesame oil (control) for 3 or 6 days. Cryostat sections of their epididymis were immunostained for CD4 or CD8 antigens. Many of the CD4⁺ and CD8⁺ T cells were found in the subepithelial layer of efferent ductules and epididymal duct and also in the interstitum in matured and immature birds. The frequencies of CD4⁺ and CD8⁺ T cells in the subepithelial layer of efferent ductules and interstitum was significantly greater in matured birds than in immature ones. The ratios of CD4⁺/CD8⁺ T cells in the efferent ductules and interstitum were not different between matured and immature birds. In the subepithelial layer of efferent ductules of immature birds, the frequencies of CD4⁺ and CD8⁺ T cells were significantly increased by Day 3 of TP-injection, followed by a decrease to the level of Day 0 by Day 6. Their frequencies were increased by EB-injection on Day 3 and 6 compared with Day 0. In the interstitum of TP-injected birds, the frequency of CD4⁺ T cells were not changed until Day 6, whereas CD8⁺ T cells increased on Day 3 and Day 6 compared with Day 0. Injection with EB caused a significant increase of both CD4⁺ and CD8⁺ T cells on Day 3 and Day 6 compared with Day 0. The CD4⁺/CD8⁺ T cells ratio in the epididymal subepithelial layer and interstitum were not significantly different among treatment days within control, TP- and EB-injected groups. These results suggest that the populations of CD4⁺ and CD8⁺ T cells in the epididymis are increased in the matured birds compared with immature ones, and luminal contents and gonadal steroids may be responsible in the increase of those T cells.

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The effect of storage time (3, 7 and 14 days), storage temperature (18±1°C and 15±1°C) and egg size (average weight -2*std.dev., -1*std.dev., +1*std.dev., and +2*std.dev.) on the incubation length of Muscovy and Pekin duck eggs was studied. Incubation was carried out in a commercial multi-stage incubator and the eggs were daily sprayed from the 10th to the day of egg transfer. Pekin duck results showed that storage from 3, through 7, to 14 days, significantly prolonged the incubation time either at 15°C or 18°C (15°C : 27.92, 28.11 and 28.31 days ; 18°C : 27.89, 28.08 and 28.25 days ; Hatch-time=27.82+0.0343storage). Similarly, egg size influenced the incubation time (27.89, 28.02, 28.11, 28.18 days, for 72.2g<>77.4g, 77.5g<>82.8g, 82.9g<>88.1g and 88.2g<>93.5g, respectively). Muscovy duck results showed that storage prolonged the incubation time : at 18°C, 33.74, 34.18 and 34.60 days, for 3, 7 and 14 days of storage, respectively ; at 15°C, 35.20 and 33.91-34.00 for 14 days and 3-7 days, respectively, (P<0.05) Hatch-time=33.48+0.097 storage. Egg size influenced the incubation time but significant differences (p<0.05) were observed only between the lighter eggs (70.4-76.2g) compared to all the other categories : 4h and 35’ less than in the reference category (76.3g-82.1g). Since optimum hatchability and duckling quality can only be achieved when chicks hatch contemporaneously, in commercial duck hatcheries the correction for the storage length and for lighter eggs in Muscovies and lighter and heavier eggs in Pekins is strongly advised.

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Changes in the localization of helper and killer T cells (CD4⁺ and CD8⁺ T cells, respectively) in hen ovarian follicles with follicular growth and ovulation were examined in this experiment. White follicles (WF), the largest and the third largest preovulatory follicles (F₁ and F₃, respectively) and the largest postovulatory follicle (POF) were collected from birds after 5hrs of oviposition. Cryostat sections were prepared and immunostained for T cells using antibodies to CD4 (antigen of helper T cells) and CD8 (antigen of cytotoxic T cells). Populations of positive cells were observed under a light microscope and counted using a computer assisted image analyzer. The CD4⁺ and CD8⁺ T cells were localized in the theca interna and externa of all examined follicles. The frequencies of CD4⁺ and CD8⁺ T cells in the theca interna were similar among each type of follicles. The frequency of CD4⁺ T cells in the theca externa was significantly decreased in F₃ and F₁ compared with WF, with a further decrease in POF (P<0.05), and that of CD8⁺ T cells was lower in F₃, F₁ and POF than WF (P<0.01). The ratio of CD4⁺/CD8⁺ T cells in the theca interna was similar among each type of follicles but significantly lower in the theca externa of POF than WF, F₃ and F₁ (P<0.05). These results suggest that the T cell subsets, responsible for cell mediated immunity, are reserved in the theca layer of ovarian follicles, whereas their population decreases with follicular growth in theca externa.

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The distribution of glucagon-like peptide-1 (GLP-1)-containing endocrine cells was investigated in the chicken intestine by using imunohistochemical and morphometrical techniques. GLP-1-immunoreactive cells were mainly distributed in the whole jejunum and ileum, and rarely found in ascending duodenum, but not in other intestinal regions. These cells had pyramidal or spindle-like shape and a cytoplasmic process reaching to the intestinal lumen. In jejunum immunoreactive cells were mainly observed in the middle part of villi, and in ileum they were mainly found in the lower part of villi and crypts. The frequencies of occurrence of GLP-1-immunoreactive cells in the proximal, middle and distal jejunum were 16.69±7.47, 22.06±10.13 and 35.88±15.17, respectively (cell numbers per mucosal area : cells/mm², mean±SD), and those in the proximal, middle and distal ileum were 41.37±15.05, 53.84±17.57 and 73.12±18.46. There were significant differences between two adjacent regions in jejunum and ileum of small intestine. These data shows that GLP-1-immunoreactive cells are distributed more densely in the distal small intestine, and GLP-1 may play an important role in this intestinal region.

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Most bird species studied thus far have no distinct brown adipose tissue (BAT) or a related type of thermogenic tissue ; however, our recent studies on cold (4- 6°C)-acclimatized chickens suggest that simultaneous increments in mRNA levels of the mitochondrial anion carriers, avian adenine nucleotide translocator (avANT) and avian uncoupling protein (avUCP), may be involved in the regulation of thermogenesis in avian skeletal muscle (FEBS Lett. 529 : 313-318, 2002). The present experiments were conducted to compare the responses of laying- and meat-type chickens in regard to the expression of avUCP and avANT when they undergo acute (24-48h) mild cold (8°C) exposure. Twenty-four male laying- and twelve meat-type chickens (3-wk old) were used. Groups from each species were exposed to mild cold for 24 and 48h, while the control group remained at 23°C. In laying-type chickens, weight gain and feed efficiency were both compensated in some degree after 48h of cold exposure. In contrast, meat-type chickens exhibited a linear decrease in weight gain corresponding to the duration of cold exposure. There were differences in the expression of avANT mRNA in Pectoralis superficialis muscle, between laying- and meat-type chickens, i.e. expression of avANT mRNA was significantly increased in laying-type chickens exposed to cold for 48h, but not in meat-type chickens. However, no differences were observed in the expression of avUCP mRNA in pectoral muscle between control and mild cold groups for both type of chickens, showing that acute mild cold exposure was not sufficient to induce increased expression of avUCP mRNA in skeletal muscle of either laying- or meat-type chickens. Up-regulation of avANT mRNA, but not avUCP mRNA, in laying-type chickens exposed to acute mild cold suggested that avANT might be involved in thermogenesis and adaptation to acute mild cold exposure. These findings will contribute to our understanding of potential differences in the responses of laying- and meat-type chickens to cold exposure at the molecular level.

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In order to examine the binding affinity of various estrogenic compounds to estrogen receptor β (ERβ), the cDNA encoding the hinge domain, the ligand-binding domain, and the C-terminal domain of quail ERβ was constructed and transfected into competent Escherichia coli. The binding assay performed using the supernatant of the cell lysates showed that bacterially-expressed ERβ has one single class of binding site for estradiol-17β with a dissociation constant of 4.90±0.16×10^-9M. The competition studies indicated that the relative binding affinities for the synthetic estrogens, diethylstilbestrol and ethinyl estradiol, are very high, while those for the xenoestrogens, bisphenol A and nonylphenol, are very low. Coumestrol, known as one of phytoestrogens, can compete with estradiol-17β with higher binding affinity for ERβ than ERα.

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Effect of dietary xylitol on antibody titers to sheep blood red cells (SRBC) and immunoglobulin (Ig) G concentration in plasma and concanvalin A stimulated-blood T cell proliferation was studied in broiler chicks. In addition, changes in feed intake, and plasma acute phase proteins concentration such as alpha-1 acid glycoprotein and ceruloplasmin following single injection of lipopolysaccharide (LPS, Salmonella enteritidis, 1.5mg/kg body weight) were also determined. Male broiler chicks (8 days of age, Ross strain) were fed either diet containing glucose or xylitol for 22 days. A SRBC suspension (5 : 100, v/v) in a phosphate buffer was intravenously injected at 15 and 25 days of age and a blood sample was obtained at 21 and 29 days of age from wing vein. Thereafter, chicks were intraperitoneally injected with LPS and blood was obtained 0, 9 and 24 hours after the injection. Growth performance for 22 days before the LPS injection did not differ between dietary groups. The antibody titers against SRBC and plasma IgG concentration were greater in chicks fed the xylitol diet than those in chicks fed the glucose diet at 21 days of age, but not at 29 days of age. Proliferation of T cell induced by Con A before the injection of LPS did not differ in dietary treatments. Significantly greater feed intake during 24 hours following LPS injections was observed in chicks fed the xylitol diet relative in chicks fed the glucose diet. Acute phase proteins concentration in plasma at 9 and 24 hours following single injection of LPS did not differ in chicks fed the xylitol and glucose diets, except ceruloplasmin concentration at 9 hours after LPS injection. The results suggested that dietary xylitol enhanced antibody production without impairing growth performance, and alleviated reduction of feed intake without impairing early inflammatory responses even when they were received relatively high level of immune stimulation.

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Quinine is known as a bitter compound for humans and also used in animal experiment. However, there is no evidence that animals share the same taste sensation of quinine with humans. The purpose of this experiment was to elucidate how chicks perceive quinine. First, 14-d-old chicks were freely fed diets varying in quinine HCl (0, 0.2, 0.4 and 0.8%) for 3 or 4d as a single diet, or given a choice between the quinine-free basal diet and a diet containing 0.2% quinine HCl for 4d. Feed intake of quinine added diets depressed within the first 4h after the start of the experiment, after which it increased with time. Especially, chicks became accustomed to 0.2% quinine HCl from the second d of the experiment. As contrasted with this result, choice-fed chicks did not differentiate between the basal diet and the diet containing 0.2% quinine HCl during the first 4h, after which they had the aversion to the quinine-added diet over 4d. Chicks fed 0.4% quinine HCl increased water intake as compared with those fed the basal diet, irrespective of the lower body weight and feed intake. Next, chicks previously fed diets containing 0, 0.2 or 0.8% quinine HCl were given a choice between the basal diet and the diet containing 0.2% quinine HCl for 24h. Chicks previously fed 0.2% quinine HCl was more sensitive to the dietary quinine than those fed the basal diet previously, but chicks fed 0.8% quinine HCl for 4d did not discriminate between the two diets. The adverse effect of quinine was not carried over, because chicks previously given the quinine-added diets ate more diet than those previously fed the basal diet immediately after the start of the experiment when they were offered a chance to eat the basal diet in the choice feeding. These results indicated that the aversive effect of quinine on chicks was associated with the uncomfortable taste sensation as humans perceived.

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The objective of this work was to develop polymorphic microsatellite markers derived from Japanese quail embryonic and cardiac cDNA libraries and to locate these markers on Kobe-NIBS Japanese quail (KNQ) linkage map constructed mainly by AFLP markers in previous study. Of the 86 positive clones, 51 clones were unique and identified as genes or ESTs by BLAST searches, and 25 from 51 clones were possible to design the PCR primers after partial sequencing. Only six markers were polymorphic and used by linkage analysis in KNQ resource family. These markers were mapped on four linkage groups, JQG 1, JQG 9, JQG 19 and JQG 66, and then these linkage groups were assigned to chromosome of Japanese quail, CJA 2, CJA 14, CJA 17 and CJA 23, respectively. These markers derived from cDNA are useful and powerful tool, and contribute to the comparative map between Japanese quail and the other species.

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In the present study, Southern hybridization analysis was used to investigate whether segregated major histocompatibility complex (MHC) genes were selected in two partly inbred Japanese quail (Coturnix japonica) lines, the H and L lines, which were selected for high (H) and low (L) antibody response against inactivated Newcastle disease virus (NDV) vaccine as a result of breeding over 45 generations by reciprocal mating. The results showed that the each restriction fragments length polymorphisms (PFLP) pattern of MHC class I, II and IV of all the individuals within the H and L lines were identical. The RFLP patterns of MHC class II in F1 offspring resulting from the H and L lines were inherited equally. This suggested that divergent selection for antibody response to inactivated NDV in Japanese quails might have induced two different MHC-homozygous lines.

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