Ontogeny of magnetoreception in chickens (Gallus gallus domesticus)

Chickens are precocial birds, capable of moving independently from within a few hours of hatching, and thus provide a useful model to investigate the development of magnetoreception in young birds. Chicks show some sharply-timed behavioural changes at around 11 days of age that may be indicative of improvements in navigation ability around this age. We trained Young (<10 days, n = 7) and Old (11 days or older, n = 6) chicks to find a hidden imprinting stimulus behind one of four screens in a square arena. Once criterion was reached, the directional choices of chicks were recorded in unrewarded tests in the geomagnetic field and in an experimental field shifted by 90° clockwise. These tests were separated with rewarded training trials to avoid extinction. In the first, and the first 3 tests, no indication was found that chicks chose the correct unimodal magnetic direction. Instead, in all tests, Old chicks preferred the screens in the same magnetic axis as the training direction in tests in the geomagnetic and shifted experimental fields significantly more than Young chicks (P < 0.05). Choices of Young chicks were no different to chance in tests, whereas choices by Old chicks were significantly different from chance (P < 0.05). Our findings support the hypothesis that magnetoreception appears in the second week of life in the chicken. It is, however, unclear when a truly directional magnetic response (i.e. an unimodal, rather than axial, response in our test) develops that could be used by the chicks for accurate navigation.     

Neurogenic inflammation in the chicken (Gallus gallus var domesticus)

1. Neurogenic inflammation has been studied in the anaesthetized adult hen using a variety of different stimuli.2. Plasma extravasation was produced following antidromic stimulation of the external mandibular ramus of the trigeminal nerve which innervates the skin at the angle of the jaw and the anterior part of the wattle.3. Stimulation of the wattle by external application of mustard oil, thermal and mechanical stimuli, as well as intradermal injection of substance P and bradykinin, all produced plasma extravasation.4. These results demonstrate that, in contrast to previous findings in the pigeon, at least in the trigeminal of the chicken peripheral C-fibre nociceptors have similar physiological characteristics in relation to the neurogenic inflammatory mechanism to those seen in mammals.     

Histocytology of the avian (Gallus domesticus) carotid body.

The histotopography of the silvery-white glistening carotid body and the branchial derivates in the cranial thoracic inlets as well as the histocytology of the particular organ were revealed by various microtechniques. Three types of randomly distributed epithelioid cells, many capillaries, and small and large sinuses are observable. Myelinated fibres are sparsely distributed. 25 clinically healthy white leghorn males were used for this investigation.     

Dietary thyroxine induces molt in chickens (Gallus gallus domesticus)

Thyroxine increases during a molt in wild and captive birds, and thyroidectomy prevents induction of molt. This trial examined the effect of dietary thyroxine on molt induction molt in chickens (laying hens, 59 weeks of age). In a completely randomized design (n=15 hens/replication; 6 replications/treatment), hens were randomly assigned to either a traditional molting program consisting of feed withdrawal (FWD), or to diets containing 40 mg thyroxine/kg diet (HT), 20 mg thyroxine/kg diet (LT), or 40 mg thyroxine from thyroactive iodinated casein/kg diet (TIC). The molting treatment lasted 7-13 d, until egg production reached 0%. After molt induction, birds had ad libitum access to the same diet, until egg production was re-initiated and maximized ( approximately 56 d). All treatments induced molt, based upon cessation of egg laying and regression of ovary and oviduct. Birds on FWD treatment lost more body weight during the molting period, but gained more after molt compared to thyroxine treatments (P<0.01 for each), although all body weights were similar when egg production was maximized. Data demonstrate that oral thyroxine, in purified or non-purified form, induces a molt and may enhance animal well-being by reducing the need for FWD.     

Genetic characterization of Bhutanese native chickens based on an analysis of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), domestic Southeast Asian and commercial chicken lines (Gallus gallus domesticus)

The genetic diversity of Bhutanese chickens needs to be understood in order to develop a suitable conservation strategy for these birds in Bhutan. In this, work, we used microsatellite markers to examine the genetic diversity of Bhutanese chickens. Four Bhutanese chicken varieties (Black plumage, Frizzle, Naked neck and Red Junglefowl-like, corresponding to Yuebjha Narp, Phulom, Khuilay and Seim, respectively), two subspecies of Red Junglefowl (Gallus gallus gallus and Gallus gallus spadecieus), two varieties of Thai native chickens (Pradhu Hang Dam and Chee; Gallus gallus domesticus) representing the Southeast Asian domestic chicken, and two commercial lines (Broiler and Single Comb White Leghorn) were genotyped with 18 microsatellites that included 16 loci recommended by the FAO/ISAG for investigations of genetic variability in chickens. All loci were polymorphic, with the number of alleles ranging from six (MCW0111) to 23 (MCW0183). Substantial genetic variation was observed in all populations, with the Bhutanese native chicken Yuebjha Narp (Black plumage chicken) showing the lowest genetic variability. Despite extensive intrapopulation variation, the genetic differentiation among 10 populations was moderate. A neighbor-joining tree revealed the genetic relationships involved while principal component analysis showed that Bhutanese native chickens should be given priority in conservation efforts because of their genetic distinctiveness. Chee chickens are especially valuable as a reservoir of predomestic diversity, as indicated by their greater genetic variation and their position in the phylogenetic tree.     

Bone response of broiler chickens (Gallus gallus domesticus) induced by corticosterone

Experiments were conducted with chickens exposed to corticosterone (CORT), with the aim of determining its effects on bone characteristics. At 7 d of age, the experimental birds were injected daily with CORT (4 mg/kg of body mass) for 1 week. CORT administration significantly decreased the body weight while increasing relative liver weight of the chickens and the bone parameters were also decreased. Histology and immunohistochemistry of type X collagen revealed that CORT reduced the lengths of proliferative and prehypertrophic zone in growth plate and the number of positive chondrocytes in the prehypertrophic zone. In conclusion exposure to CORT depressed the growth performance and retarded the longitudinal growth of the long bones by inhibiting the proliferation and differentiation of chondrocytes in growth plate in broilers.     

Development of cholinergic chronotropic control in chick (Gallus gallus domesticus) embryos

In chick (Gallus gallus domesticus) embryos, instantaneous heart rate begins to fluctuate with the appearance of rapid, transient decelerations at around the end of the second week of incubation. Previously, it was shown that instantaneous heart rate decelerations were eliminated by administration of atropine and concurrently heart rate baseline was elevated in late embryos. Because the previous study lacked statistical treatment and there has been recent controversy over the development of tonic vagal control of the heart, we reexamine the hypothesis that transient decelerations of instantaneous heart rate are mediated by vagus nerve and the vagal tone begins to appear at around the end of the second week of incubation. Atropine administration tests were conducted for sixty-seven 11- to 14-day-old and 18-day-old embryos in total. Heart rate decelerations appeared sporadically in three out of ten 12-day-old embryos, but the difference of mode heart rate before and after administration of atropine was not significant. Seven out of nine 13-day-old embryos and all nine 14-day-old embryos showed heart rate decelerations and the difference of mode heart rate before and after atropine administration was significant. In late (18-day-old) embryos, magnitude and frequency of instantaneous heart rate decelerations further increased with additional appearance of transient, irregular accelerations. Administration of varying doses of atropine completely eliminated the heart rate decelerations and elevated the heart rate baseline more markedly than in young embryos, indicating the maturation of vagal tone late in incubation.     

Responses of domestic chicks (Gallus gallus domesticus) to multimodal aposematic signals

Many aposematic prey combine their visual warning signals withadditional signals. Together, these signals constitute a multimodalor multicomponent warning display. The additional signals arethought to increase the effects of the visual signals on predators.Olfactory signals are much emphasized, but later studies haveshown that also auditory signals like the buzzing of certaininsects might have multimodal effects. The wasp displays typicalvisual aposematic signals, black and yellow stripes, but doesalso emit a characteristic buzzing. We wanted to test if, andin what way, the visual and acoustic display of the wasp hasan aversive function on the predators. We therefore conducteda 12-trial discrimination-learning task on inexperienced chicksto study whether there are innate biases toward these signalsand how they affect the speed of avoidance learning. We alsoperformed three extinction-learning trials to study how memorablethe signals were to the chicks. We show that the visual signalsin the display of the wasp contribute to the protection frompredators but in different ways; the yellow color had an aversiveeffect on inexperienced predators, while the striped patternimproved the aversion learning. The sound did not enhance theinnate aversions but increased the aversion learning of stripesin green prey.     

Abattoir-sourced isolated ileum from Gallus gallus domesticus as an experimental tool

A study was undertaken to determine the longevity of active muscarinic receptors on abattoir-sourced isolated ileum preparations from Gallus gallus domesticus, with a view to using the tissue as an experimental tool for functional response assays in laboratory experiments. A concentration-response curve for acetylcholine (1-256 μM) was plotted, in the presence and absence of 1, 3 and 6 nM atropine. In a second experiment, unknown concentrations of acetylcholine samples were determined by using an interpolation method. In this experiment, four sample concentrations were used and the calculated values were found to be almost equal to the actual values. Finally, an experiment was carried out to elucidate the effects of post-sacrifice time on the contractile response of the tissue. The results showed that the tissue maintained considerable contractile response at the 6-hour post-sacrifice time-point. Competitive antagonistic activity was observed between acetylcholine and atropine on the chicken ileum, and the pA2 value was calculated to be 9.21 by using an Arunlakshana-Schild plot. The results suggest that isolated ileum preparations of Gallus gallus domesticus, obtained from a meat abattoir, can be used as a basic experimental tool for bioassays in routine laboratory experiments. However, its potential as a research tool still needs to be confirmed.     

红原鸡与家鸡的亲缘关系研究

对中国红原鸡滇地亚种和海南亚种与我国茶花鸡,泰和鸡和寿光鸡等地方鸡种以及芦花鸡,洛岛红等外国鸡种进行了血型（３个位点,１３个等位基因）,蛋白质（酶）多态（５个位点,１１个等位基因）和ＤＮＡ指纹分析,结果表明,红原鸡与茶花鸡（原始型品种）的亲缘关系较近;与泰和鸡,寿光鸡,芦花鸡,洛岛红（进化型品种）的亲缘关系较远,呈红原鸡－茶花鸡－泰和鸡,寿光鸡或芦花鸡,洛岛红这样一个进化阶梯,以上结果与国外资料（     

北京油鸡purH基因结构与表达特征研究

提取北京油鸡8种组织的总RNA,利用RT-PCR检测purH基因mRNA的差异表达。将purH基因完整开放阅读框定向插入pEGFP-N3,构建带有GFP报告基因重组表达载体pEGFP-purH,利用脂质体介导法将其导入北京油鸡体外培养细胞中,进行G418药物筛选和克隆化培养。结果表明：北京油鸡purH基因（GenBank 登录号：EU334506）编码区为1782 bp,编码 593 aa的多肽,转染后24 h、48 h和72 h,pEGFP-purH转染率在10.3 %～53.2 %之间,绿色荧光均匀分布于细胞质与细胞核中,随表达量的增加,绿色荧光在细胞核中聚集成团块状或颗粒状。经药物筛选和克隆化培养,获得表达pEGFP-purH融合蛋白的克隆细胞株,RT-PCR与Western blotting检测确认pEGFP-purH已整合到北京油鸡成纤维细胞基因组中,在优化的条件下,阳性细胞凋亡率、生长与增殖状况与对照组比较差异不显著（P 〉0.05）。     

Isolation of Dermatophytes and Related Species from Domestic Fowl (Gallus gallus domesticus)

We investigated 793 bird combs [645 chickens and 148 fighting cocks (Shamo)] to determine the prevalence of dermatophytes and their related fungal species. The targeted fungal species were recovered from 195 of the 793 examined birds (24.6 %). Prevalence ratios were compared in temperate (the mainland) and subtropical (Nansei Islands) areas, genders, strains, breeding scale (individual and farm), and housing system (in cage and free ranging). The frequency of the fungal species in the mainland, males, fighting cocks, breeding scale by individual nursing, and free-range housing system exhibited significantly higher positive ratios than that in the other groups. A total of 224 dermatophytes and related species were isolated, including 101 Arthroderma (Ar.) multifidum, 83 Aphanoascus (Ap.) terreus, five Uncinocarpus queenslandicus, two U. reesii, two Ap. pinarensis, one Amauroascus kuehnii, one Ar. simii, one Gymnoascus petalosporus, one Microsporum gallinae, and 28 Chrysosporium-like (Chrysosporium spp.) isolates, which were identified using internal transcribed spacer regions of ribosomal RNA gene sequences. The predominant fungal species in the mainland was Ap. terreus and that in the Nansei Islands was Ar. multifidum. Pathogenic fungal species to humans and animals were limited to M. gallinae and Ar. simii, which corresponded to 0.025 % of the isolates in this study.     

Depolarisation and repolarisation sequences of ventricular epicardium in chickens (Gallus gallus domesticus)

Activation and recovery sequences were mapped by means of 64-channel synchronous recording of extracellular potentials on ventricular epicardium in chickens. Ventricular epicardium was depolarized due to multiple breakthroughs. The recovery of ventricular epicardium occurs from the apex to the base of heart and does not repeat the activation sequence. Gradients of repolarisation exist over the ventricular epicardium in birds. Repolarisation pattern of ventricular epicardium depends primarily on intrinsic spatial heterogeneities of ARIs over epicardium.     

Genistein affects testosterone secretion by Leydig cells in roosters (Gallus gallus domesticus)

Genistein is one of non-steroidal phytoestrogens present in soya and soybean products as well as in other legumes. Phytoestrogens possess estrogen-like biological activity and may influence human and animal reproduction. The aim of this study was to examine the effect of genistein on testosterone (T) secretion by isolated Leydig cells in roosters. Genistein (5-50 microM) inhibited (p<0.05) in vitro basal and LH-stimulated T secretion by Leydig cells in a dose dependent manner. No significant effect of lavendustin C (inhibitor of PTK, a non-phytoestrogen) on the T production was observed. In conclusion, genistein, present in commercial poultry feeds, may influence testicular steroidogenesis but its effect on reproductive performance of roosters requires further examinations.     

Divergent selection on feather pecking behaviour in laying hens (Gallus gallus domesticus)

A selection experiment was initiated in 1996 in which selection for (HP line) and against (LP line) feather pecking was performed. The foundation stock was a White Leghorn layer strain established in 1970 and maintained since then as a random bred control line at the Institute. Six hatches were produced over three generations. At the age of 68 weeks (generation 0, 1996), 35 weeks (generation 1, 1997), 30 weeks (generation 2, 1998), and 27 weeks (generation 3, 1999) female birds were transferred to observation pens and their feather pecking behaviour was recorded. In each generation, 30 females and 8 males were selected from approximately 200 females and 60 males. The selection criterion was breeding value estimated by animal model on the trait 'number of bouts of feather pecking per bird per hour'.Feather pecking behaviour in adult hens was significantly higher in HP than in LP. In generation 2 the following was recorded: 3.10 versus 1.37 bouts per bird per hour (P<0.01), 7.04 versus 3.58 pecks per bird per hour (P<0.05) and the proportion of hens recorded feather pecking in the 180min observation period was 67 versus 56% (P<0.05). In generation 3 the following was recorded: 4.56 versus 0.63 bouts per bird per hour (P<0.001), 13.9 versus 2.51 pecks per bird per hour (P<0.001) and the proportion of hens recorded feather pecking in the 180min observation period was 75 versus 49% (P<0.001).In generation 3, plumage condition was better in LP on neck, breast, back, wings and tail, as well as overall (P<0.001). Body weight did not differ between lines in generation 2, but in generation 3, HP hens were on average heavier than LP hens at the age of 27 weeks (1435g versus 1371g, P<0.001).     

Sex inversion in domestic chicken (Gallus gallus domesticus) by letrozole and tamoxifen

In multicellular organisms, determination of sex identity is a complex, multistage process. Sex hormones are synthesized in gonads and fulfill the role of inductors in this process. The effect of androgen is currently well studied. However, the participation of estrogen in the formation of female gonads and female sex on the whole is not much known. Here, we present the results of experimental sex inversion by inhibition of aromatase (an enzyme involved in estrogen synthesis) and tamoxifen (a modulator of estrogen receptors) in chick embryos. It was shown that masculinization depended on the dose of the substance and quantity of injections. Inhibition of aromatase did not block the meiotic prophase in oogoniums. It has been suggested that retinoic acid and estrogens have different mechanisms of effect on oogenesis. Proteins and nucleoproteins interacting with estrogen receptor 1 and their gene localization in human and chicken genomes have been shown for the first time.     

Cell number and sex ratio in unfertilized chicken eggs (Gallus gallus domesticus)

In chickens and other birds, females have two different sex chromosomes (ZW), whereas males carry two homologous sex chromosomes (ZZ). The primary sex ratio can thus be determined by genetic analysis of the sex chromosome of the ovum before fertilization. Sex diagnosis is more reliable when there are more cells, i.e. sufficient DNA, for the analysis. In this study, eggs from virgin hens were incubated for 3 days and the number of cells in the germinal discs was counted. A median of 2.5 cells was counted with a range of two to 20 cells. We also counted cells in the germinal discs of unfertilized eggs of inseminated hens and recorded a median of three cells and a range of two to 40 cells. Sex diagnosis based on polymerase chain reaction (PCR) amplification of Z and W chromosomes specific fragments from the CHD1 gene in 30 incubated eggs obtained from 35-week-old virgin hens gave a ratio of 13 Z to 15 W chromosomes with two samples undetermined.The unfertilized eggs of three groups of chickens were subjected to sex diagnosis to supplement the sex ratio data of an incubation experiment (see companion paper). The high proportion of Z chromosomes diagnosed in all three groups by two independent gene products suggests a sex difference on developmental potential and/or a sex chromosome segregation biased toward males in unfertilized eggs especially at the beginning of reproduction.     

Identification of a novel mtDNA lineage B3 in chicken (Gallus gallus domesticus)

DEAR EDITOR, In this study,we sequenced the complete mitochondrial DNA genome (mitogenome) of the Zhengyang Yellow chicken (Gallus gallus domesticus) by next-generation sequencing technology.Samples were taken from Zhumadian city,Henan Province,China.The complete mitogenome was 16 785 bp in size,and had a nucleotide composition of 30.3％ (A),23.7％ (T),32.5％ (C),and 13.5％ (G),with a high AT content of 54.0％.The assembled mitogenome exhibited typical mitochondrial DNA (mtDNA) structure,including a non-coding control region,two rRNA genes,13 protein-coding genes,and 22 tRNA genes.Phylogenetic analysis indicated that this mitogenome defined a novel sub-haplogroup B3 within haplogroup B.These results should provide essential information for chicken domestication and insight into the evolution of genomes.     

Ultradian activity rhythms in large groups of newly hatched chicks (Gallus gallus domesticus)

A clutch of young chicks housed with a mother hen exhibit ultradian (within day) rhythms of activity corresponding to the brooding cycle of the hen. In the present study clear evidence was found of ultradian activity rhythms in newly hatched domestic chicks housed in groups larger than natural clutch size without a mother hen or any other obvious external time-keeper. No consistent synchrony was found between groups housed in different pens within the same room. The ultradian rhythms disappeared with time and little evidence of group rhythmicity remained by the third night. This disappearance over time suggests that the presence of a mother hen may be pivotal for the long-term maintenance of these rhythms. The ultradian rhythm of the chicks may also play an important role in the initiation of brooding cycles during the behavioural transition of the mother hen from incubation to brooding. Computer simulations of individual activity rhythms were found to reproduce the observations made on a group basis. This was achievable even when individual chick rhythms were modelled as independent of each other, thus no assumptions of social facilitation are necessary to obtain ultradian activity rhythms on a group level.