Neuropeptide Y (NPY) is known to be an essential orexigenic signal in mammalian and avian brain. Since NPY receptors in the avian brain have not been clarified, to determine whether Y1 receptor or Y1-like receptor(s) mediates the orexigenic effect of NPY in neonatal chicks was examined by using BIBP3226, a selective nonpeptide Y1 receptor antagonist for mammals. Central administration of BIBP3226 (5 or 10μg) did not alter fasting-induced food intake in Experiment 1. In the second experiment, when BIBP3226 (5μg) and NPY (0.5μg) were co-administrated, BIBP3226 did not abolish NPY-induced food intake. These results suggest that Y1- or Y1-like receptor(s) do not play a significant role in regulating food intake of the neonatal chick.

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To identify the quantitative trait loci (QTL) affecting abdominal fat deposition in chickens, we carried out QTL analysis on this trait using a resource population of 222 F₂ progeny from a cross between a Satsumadori (a Japanese native breed showing little abdominal fat deposition) male and a White Plymouth Rock (a broiler breed showing significant abdominal fat deposition) female. We chose 78 microsatellite loci from 331 loci publicly available of 14 linkage groups, based on their utility and location. One QTL affecting the ratio of abdominal fat deposition to live body weight (abdominal fat %) at 16 weeks of age was mapped at 38.0cM on chromosome 7, with a LOD score of 7.0. The closest loci to the QTL was MCW316. The QTL was located between markers MCW316 and MCW92, being 1.0cM apart from MCW316. The difference in abdominal fat % in F₂ was associated with allele types of MCW316 (P<0.0005), which suggests the possibility of marker-assisted selection for abdominal fat deposition in chickens.

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We investigated the central effect of the estrogenic pollutant, bisphenol A (BPA), on behaviors, growth and several organ weights in chicks.
Four-day-old male chicks were injected into the brain with BPA at doses of 0, 100, 200μg. Food intake and body weight gain were determined, but no significant effects of BPA were detected. Secondly, behaviors of these chicks were tested under an isolated situation. The behaviors such as frequency of jumping, distress vocalization and duration of crouching were monitored. Central injection of BPA increased distress vocalizations in a dose-dependent manner, though no significant changes were observed in other indices. Thereafter, four organ (testis, kidney, liver and brain) weights were measured. No significant differences in all the organs were detected among all treatments.
These results suggest that the accumulation of BPA in the central nervous system may somewhat induce the behavioral change in a stressful situation.

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Tea saponin is known to suppress chick growth rate by decreasing feed intake, although the mechanism by which tea saponin decreases feed intake remains obscure. Since tea saponin has bitter taste, palatability was suggested to be a major factor affecting feed intake. However, there are some experimental results showing another possibility. The present experiment was conducted with chicks to evaluate the involvement of taste in the adverse effect of tea saponin on feed intake. When Single Comb White Leghorn male chicks were given a casein diet for at least 4h in experiments 1 and 2, 1% tea saponin depressed feed intake. The decrease in feed intake immediately after feeding (0-2h) was rather mild and became severer with time (2-4h). Removal of saponin from the diet increased feed intake, and this beneficial effect was manifested for the 2-4h of the feeding period as compared with the first 2h. In experiment 3, 40mg of tea saponin was administered directly to the proventriculus by capsules to avoid the effect of taste or orally as a 1% solution. Despite the fact that chicks were given free access to the saponin-free diet after the administration, the depression in feed intake due to saponin was lasted until 8h had passed, irrespective of different dosing methods. These results show that the aversion to the saponin-added diet does not occur immediately after the ingestion of tea saponin and that the adverse effect of tea saponin on feed intake is carried over. Thus, it seems unlikely that taste is a primary factor decreasing feed intake in chicks given tea saponin.

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To investigate the effects of dietary charcoal powder including wood vinegar compounds (4:1, CWVC) on the intestinal villus morphology, 130-d-old male Single Comb White Leghorn chickens were randomly allotted into 0, 1, 3 and 5% dietary CWVC groups of each 8 bird. Four rations were formulated by addition of each level of CWVC (CP: 2.5%) to commercial layer finisher mash diet (CP: 14.5%, ME: 2,803kcal/kg), and fed ad libitum for 28d. During the feeding experimental period, feed intake and body weight gain were measured. After the end of feeding experiments, 4 birds were randomly selected per each group, and intestinal villus height, epithelial cell area and cell mitosis in each intestinal segment were compared using a light microscope. Besides, the morphological change of villus tip surface was observed using a scanning electron microscope.
Although the feed intake did not differ among each group, the body weight gain tended to be higher in 1 and 3% dietary CWVC groups than that of 0% group, resulting in the feed conversion ratio being insignificantly improved in these groups.
Values of the intestinal villus height, epithelial cell area and cell mitosis were higher in 1% dietary CWVC group but lower in 5% dietary CWVC group than those of another groups in each intestinal segment.
The comparatively smooth surface of the duodenal villus apex in the 0% dietary CWVC duodenum changed to the rough surface with a clear cell outline between each epithelial cell due to the conspicuous cell protuberances after feeding 1% dietary CWVC. However, such conspicuous cell protuberances disappeared and cells having no microvilli and deep cells at the sites of recently exfoliated cells were observed after feeding 3% dietary CWVC, and the latter was much increased after feeding 5% dietary CWVC. Fundamentally, the villus apex surface in the jejunum and ileum revealed an almost similar morphological alteration to that in the duodenum except that cells having no microvilli and deeper cells due to recently exfoliated cells were not seen even in 5% dietary CWVC and that the cell protuberances of 1% dietary CWVC became faint with moving caudally.
The present morphological changes of intestinal villi in chickens fed the dietary CWVC diets demonstrate that the villus function could be activated also in the ileum at 1% level, and that such an activated villus function in all small intestinal segment parts might improve the feed conversion ratio.

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This experiment was designed to produce chimeric chicken by transferring primordial germ cells (PGCs) of Ehime native chicken embryos to White Leghorn ones. Fertilized eggs produced by both chicken breeds were incubated until stage 12-15 of embryonic development. The donor PGCs were taken out from blood vessel of Ehime native chicken embryos and injected into blood vessel of White Leghorn ones at the same stage. After the injection, the recipient eggs were incubated until hatching. Finally, three hatchlings including one male and two females were obtained. The birds survived to sexual maturity were used for progeny test to check chimerism. Of 29 offspring obtained by progeny test, 15 chicks showed feather color which was considered to be derived from Ehime native chicken. The present results suggest that the production of chimeric chicken by means of the transfer of PGCs may be able to restore genetic resources from endangered domestic chicken or some of the wild birds.

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A polymerase chain reaction (PCR) primer set for a chicken microsatellite locus on the Z chromosome, LEI0171 (GenBank Accession No.X85538), amplified a 363bp fragment of genomic DNA in chickens (Gallus domesticus) but not in quail (Coturnix japonica). A concentration of at least 10pg/μl of chicken DNA in the reaction mixture resulted in detectable amplification of the PCR product. Circulating primordial germ cells (PGCs) of chick embryos were transfused into quail embryos, and the chicken-genome-specific PCR product was observed in the chick-PGC-transfused chimeric quail when DNA samples were extracted from whole day-6 embryos, day-10 and -15 embryonic gonads, gonads of 5-day chicks, and the semen of adults.

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The reported effects of dietary supplemented microbial phytase on the utilization of phytate phosphorus (pP) differ widely by investigators. In order to clarify the differences, the contents of total phosphorus (P) and pP in commonly used five plant feedstuffs, corn (C), soybean meal (SM), defatted rice bran (RB), wheat bran (WB) and high level flour wheat bran (FWB) were determined, and the effect of microbial phytase on utilization of pP in these feedstuffs was studied using male broiler chicks.
The contents of total P in plant feedstuffs were determined to be 0.25, 0.67, 2.81, 1.04 and 0.54%, and those of pP to be 0.15, 0.31, 2.02, 0.71 and 0.32% in C, SM, RB, WB and FWB, respectively. The ratios of pP to total P ranged from 47.2% (for SM) to 71.8% (for RB). The experimental diets were formulated using C, SM, RB, WB or FWB as a sole source of pP. Male broiler chicks were fed the diets supplemented by 0 or 500 phytase units/kg of diet microbial phytase for 10 days from 7 to 17 days of age. There were large differences in pP retention among plant feedstuffs without microbial phytase. Especially the retention was low (5.4%) in the C and high (73.4%) in the WB. The pP retention in SM, RB and FWB were 52.3, 42.5 and 51.1%, respectively. On the other hand, with the addition of microbial phytase, pP retention in C, SM, RB, WB and FWB increased to 69.9, 75.0, 78.6, 86.6 and 84.1%, respectively.

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Eight commercial Single Comb White Leghorn hens were used to study the effects of high ambient temperature on behavioral activities and to select a better parameter for the estimation of heat production between activity count and standing time. The hens were kept at ambient temperatures of 25, 29, and 33°C and fed ad libitum. Daily feed intake and heat production decreased with the increase of temperature. Daily total standing time increased significantly with the increase of temperature, specially the increase occurred in the dark periods at 29 and 33°C, and were 247% (P<0.01) and 413% (P<0.01), respectively, compared to the standing time at 25°C. Heat production per hour decreased significantly (P<0.01) in both the light and dark periods with the increase of temperature. On the other hand, the daily activity counts were almost the same at all the temperatures. The levels of activity counts per hour increased significantly (P<0.01) during the dark periods at 29 and 33°C in comparison with that of at 25°C. Heat production per activity count decreased significantly (P<0.01) with the increase of temperature. The hens changed their behavioral pattern, and minimized heat production when introduced to higher temperatures. From the analysis of variance of the multiple regression equations, the contribution rates of activity counts (counts/h) and standing time (min/h) towards total heat production (kJ/kg^0.75/h) were 65% and 23%, respectively. Therefore, activity counts give better results in regards to estimating heat production in White Leghorn hens.

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In order to evaluate the involvement of taste in the decreased feed intake due to tea saponin, the preference for a diet containing saponin or cholesterol was studied in chicks given diet selection. When chicks were fed the basal diet added with 1% saponin ad libitum for 4-6h, feed intake decreased within 2h and the decrease in feed intake was became severer with time. Chicks given the choice between the basal and saponin-added diets for 12h selected the basal diet exclusively during 4-12h, but there were no significant differences in feed intake between the two diets during the first 4h. Chicks preferred the basal diet to the saponin-added diet when the two-choice preference test was prolonged to 8d. However, there were large individual differences in the feeding response among chicks; some chicks selected the basal diet from the start of the test, but others needed more time to select the basal diet. These individual differences were disappeared with fixing the feeder positions rather than changing the feeder positions every day. The deleterious effect due to tea saponin did not occur when equal amounts of cholesterol were supplemented to the saponin-added diet. However, chicks did not show the special preference for cholesterol, when they were given the choice between the basal diet and a diet containing 1% cholesterol for 12h or between the basal diet and a diet containing saponin plus cholesterol at 1% levels for 8d. These results suggest that chicks can recognize the presence of saponin, but taste is not a major determinant responsible for the depression in feed intake due to saponin.

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Chicken primordial germ cells isolated from embryonic blood were cultured in vitro on feeder cells derived from the gonads of 7-day incubated embryos. Primordial germ cells were proliferated about 13 times during the 4 day culture period on the feeder cells without mytomycin C treatment. When the feeder cells were treated with mytomycin C for 1 hour, primordial germ cells proliferated about 7 times by day 3 of culture and then decreased in number. When the feeder cells were treated with mytomycin C for 2-3 hours, almost no proliferation of primordial germ cells was observed. These results suggest that the interaction between primordial germ cells and feeder cells for proliferating primordial germ cells was suppressed by treating the feeder cells with mytomycin C.

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The effect of corticosterone (CTC) at low and high concentrations on proliferation and differentiation was studied in chick myoblasts. Chick myoblasts were incubated with low (3ng/ml) and high (30ng/ml) levels of CTC. DNA content and creatine kinase activity were measured as indices of cell proliferation and differentiation, respectively, at 2, 4 and 6 days of incubation. DNA content was increased by CTC at low level regardless of the incubation time. Creatine kinase activity was decreased by the low level of CTC. On the other hand, the high level of CTC increased creatine kinase activity on day 2 and 4 but not on day 6. These results indicate that a low level of CTC stimulates proliferation but inhibits differentiation, while a high level of CTC stimulates differentiation but not proliferation in chick myoblasts. Furthermore, it is indicated that a long term treatment with high level of CTC also inhibits differentiation.

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Analysis of N^τ-methylhistidine is intricate and time consuming. In the present study, a modified technique using high-performance liquid chromatography, which utilizes a reversed-phase separation with ion pairing and post column fluorescence derivatization for the analysis of N^τ-methylhistidine in chicken feed and excreta is described. Two ml of the hydrolyzed sample was applied directly into the ion-exchange resin column without evaporation of HCl to roughly separate N^τ-methylhistidine from acidic and neutral amino acids. The N^τ-methylhistidine fraction was eluted with 1M pyridine and then evaporated, and the residue was dissolved in the mobile phase and subjected to high-performance liquid chromatography. The present method shortened the time needed to complete the assay by about 30min per sample and improved the separation of N^τ-methylhistidine.

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Ghrelin, a novel growth hormone (GH)-releasing acylated peptide, is recently isolated from rat stomach. This peptide stimulates the release of GH from the anterior pituitary through the GH secretagogue receptor and feeding in the rat. However, intracerebroventricular (ICV) injection of rat ghrelin inhibited feeding of chicks under both ad libitum feeding and fasting conditions (Furuse et al., 2001). Thus, we have investigated the behavioral changes by ghrelin with special reference to sleep-like behavior of the neonatal chick in two experiments. Four behavioral categories were distinguished and scored as follows: 1, standing with eyes open; 2, sitting with eyes open; 3, standing with eyes closed; and 4, sitting motionless with head drooped (sleeping posture). Firstly, ICV injection of 0, 1.25, 2.5 and 5μg of ghrelin was done to ad libitum fed birds. Secondly, several doses (0, 0.5, 1 and 2μg) of ghrelin were injected ICV into chicks previously deprived of food for 3h. In both experiments, scores of ghrelin treated birds were higher than those of control birds. These results suggest that one of the central roles of ghrelin in the neonatal chick is induction of sleep.

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