China as a Center of Origin and Domestication of Chicken: A Review

China has about 107 local chicken breeds and is considered one of the richest countries in terms of genetic resources. This diversity is a source of richness natural resources across the globe and is regarded as an excellent material for genetic improvement of breeds or breeding new breeds around the world. The present review highlights the recent evidence and studies of chicken origin and domestication in China and Southeast Asia. The evidence of molecular genetics and archeological results supported that multiple regions and event were contributed to the creation of chicken evolution from Red Jungle fowl and the findings proposed that one of events happened in domestication of chicken 8000 BP in Southeast of Asia. Several researchers confirmed that China was declared as most important of the world as a first centers for the chicken’s domestication and these chickens have remained in many archaeological sites in China.

Effects of Cyclic Chronic Heat Stress on the Expression of Nutrient Transporters in the Jejunum of Modern Broilers and Their Ancestor Wild Jungle Fowl

Heat stress (HS) has been reported to disrupt nutrient digestion and absorption in broilers. These effects may be more prominent in fast-growing chickens due to their high metabolic activity. However, the underlying molecular mechanisms are not yet fully elucidated. Hence, the current study aimed to evaluate the effect of chronic HS on jejunal nutrient transport in slow- (Athens Canadian Random Bred, ACRB from 1950), moderate- (The 1995 random bred, 95RAN), rapid- (modern broilers, modern random bred, MRB) growing birds and their ancestor wild jungle fowl (JF). One-day male chicks (n = 150/line) were placed by line in environmentally controlled chambers and kept under the same industry-standard environmental conditions until d28. On d29, an 8-h daily cyclic HS (36°C) was applied to half of the chambers, which lasted until d55, while keeping the rest under thermal neutral (TN, 24°C) conditions. Jejunum tissues were collected for morphology assessment and molecular analysis of carbohydrate-, amino acid-, and fatty acid-transporters. MRB exhibited the highest body weight (BW) followed by 95RAN under both conditions. HS decreased feed intake (FI) in MRB and 95RAN, which resulted in lower BW compared to their TN counterparts; however, no effect was observed in ACRB and JF. MRB showed a greater villus height (VH) to crypt depth (CD) ratio under both environmental conditions. Molecular analyses showed that glucose transporter (GLUT) 2, 5, 10, and 11 were upregulated in MRB compared to some of the other populations under TN conditions. HS downregulated GLUT2, 10, 11, and 12 in MRB while it increased the expression of GLUT1, 5, 10, and 11 in JF. GLUT2 protein expression was higher in JF compared to ACRB and MRB under TN conditions. It also showed an increase in ACRB but no effect on 95RAN and MRB under HS conditions. ACRB exhibited greater expression of the EAAT3 gene as compared to the rest of the populations maintained under TN conditions. HS exposure did not alter the gene expression of amino acid transporters in MRB. Gene expression of CD36 and FABP2 was upregulated in HS JF birds. Protein expression of CD36 was downregulated in HS JF while no effect was observed in ACRB, 95RAN, and MRB. Taken together, these data are the first to show the effect of HS on jejunal expression of nutrient transporters in three broiler populations known to represent 70 years of genetic progress in the poultry industry and a Red Jungle Fowl population representative of the primary ancestor of domestic chickens.

Characterization of the chicken T cell receptor γ repertoire by high-throughput sequencing

Background As one of “γδ-high” species, chicken is an excellent model for the study of γδ T cells in non-mammalian animals. However, a comprehensive characterization of the TCRγδ repertoire is still missing in chicken. The objective of this study was to characterize the expressed TCRγ repertoire in chicken thymus using high-throughput sequencing. Methods In this study, we first obtained the detailed genomic organization of the TCRγ locus of chicken based on the latest assembly of the red jungle fowl genome sequences (GRCg6a) and then characterized the TCRγ repertoire in the thymus of four chickens by using 5′ Rapid Amplification of cDNA Ends (5′ RACE) along with high-throughput sequencing (HTS). Results The chicken TCRγ locus contains a single Cγ gene, three functional Jγ segments and 44 Vγ segments that could be classified into six subgroups, each containing six, nineteen, nine, four, three and three members. Dot-plot analysis of the chicken TCRγ locus against itself showed that almost all the entire zone containing Vγ segments had arisen through tandem duplication events, and the main homology unit, containing 9 or 10 Vγ gene segments, has tandemly duplicated for four times. For the analysis of chicken TCRγ repertoire, more than 100,000 unique Vγ-region nucleotide sequences were obtained from the thymus of each chicken. After alignment to the germline Vγ and Jγ segments identified above, we found that the four chickens had similar repertoire profile of TCRγ. In brief, four Vγ segments (including Vγ3.7, Vγ2.13, Vγ1.6 and Vγ1.3) and six Vγ-Jγ pairs (including Vγ3.7-Jγ3, Vγ2.13-Jγ1, Vγ2.13-Jγ3, Vγ1.6-Jγ3, Vγ3.7-Jγ1 and Vγ1.6-Jγ1) were preferentially utilized by all four individuals, and vast majority of the unique CDR3γ sequences encoded 4 to 22 amino acids with mean 12.90 amino acids, which exhibits a wider length distribution and/or a longer mean length than CDR3γ of human, mice and other animal species. Conclusions In this study, we present the first in-depth characterization of the TCRγ repertoire in chicken thymus. We believe that these data will facilitate the studies of adaptive immunology in birds.

Genetic Diversity of MHC B-F/B-L Region in 21 Chicken Populations

The chicken major histocompatibility complex (MHC) on chromosome 16 is the most polymorphic region across the whole genome, and also an ideal model for genetic diversity investigation. The MHC B-F/B-L region is 92 kb in length with high GC content consisting of 18 genes and one pseudogene (Blec4), which plays important roles in immune response. To evaluate polymorphism of the Chinese indigenous chickens as well as to analyze the effect of selection to genetic diversity, we used WaferGen platform to identify sequence variants of the B-F/B-L region in 21 chicken populations, including the Red Jungle Fowl (RJF), Cornish (CS), White Leghorns (WLs), 16 Chinese domestic breeds, and two well-known inbred lines 63 and 72. A total of 3,319 single nucleotide polymorphism (SNPs) and 181 INDELs in the B-F/B-L region were identified among 21 populations, of which 2,057 SNPs (62%) and 159 INDELs (88%) were novel. Most of the variants were within the intron and the flanking regions. The average variation density was 36 SNPs and 2 INDELs per kb, indicating dramatical high diversity of this region. Furthermore, BF2 was identified as the hypervariable genes with 67 SNPs per kb. Chinese domestic populations showed higher diversity than the WLs and CS. The indigenous breeds, Nandan Yao (NY), Xishuangbanna Game (XG), Gushi (GS), and Xiayan (XY) chickens, were the top four with the highest density of SNPs and INDELs. The highly inbred lines 63 and 72 have the lowest diversity, which might be resulted from a long-term intense selection for decades. Collectively, we refined the genetic map of chicken MHC B-F/B-L region, and illustrated genetic diversity of 21 chicken populations. Abundant genetic variants were identified, which not only strikingly expanded the current Ensembl SNP database, but also provided comprehensive data for researchers to further investigate association between variants in MHC and immune traits.

↵​A Copro-parasitological Surveillance on Diverse Captive Wild Avian Species

Background: Infections with gastrointestinal parasites are widespread and a major health issue for captive birds. Despite the significance being well known, not much studies have been conducted on its prevalence especially in captive avians in a zoo setup. The present study aims at determining the prevalence of parasites in captive birds of different orders maintained at Bannerghatta Biological Park, Bengaluru, Karnataka. Methods: In this investigation, a survey through fecal sample examination was conducted to assess the parasitic infection in captive birds belonging to 6 different biological orders e.g. Casuariiformes, Anseriformes, Galliformes, Pelecaniformes, Psittaciformes {Emu (Dromaius novaehollandiae), Duck (Anas platyrhynchos), Peafowl (Pavo cristatus), red jungle fowl (Gallus gallus), grey pelican, (Pelecanus philippensis), purple heron (Ardea purpurea), silver pheasant (Lophura nycthemera), macaw (Ara ararauna), parakeet (Psittacula eupatsia)} and Ciconiiformes maintained at Bannerghatta Biological Park, Bengaluru, Karnataka. A total of 106 fecal samples from apparently healthy birds including 7 samples from emu, 3 ducks, 12 peafowls, 8 red jungle fowls, 24 grey pelicans, 1 purple heron, 13 silver pheasants, 8 macaws, 26 parakeets and 4 Indian open-billed storks were collected during 2015-2016 and were screened for parasitic eggs/oocysts. Result: The screening result could detect ova of 2 (28.57%) Eimeria oocyst in emu, 3 (100%) Eimeria oocyst in duck, 7 (58.33%) Capillaria sp., 3 (25%) Eimeria oocyst, 2 (16.66%) Ascardia galli, 2 (16.66%) Raillietina echinobothrida, 1 (8.33%) Tetrameres sp. in peafowls, 3 (37.5%) Ascardia galli, 1 (12.5%) Eimeria oocyst in red jungle fowls, 5 (20.83%) Ascardia galli in grey pelican, 1 (100%) trematode ova in purple heron, 3 (23.07%) Raillietina sp., 2 (15.38%) Eimeria ocyst in silver pheasant, 2 (25%) Ascaris sp. in macaw, 12 (46.15%) Ascaris sp., 3 (11.53%) Eimeria oocyst in parakeet and 4 (100%) Tetrameres sp. in Indian open-billed storks.

Keel bone fractures are more prevalent in White Leghorn hens than in Red Jungle fowl hens—A pilot study

Fractures and deviations to the keel bone are common in commercial laying hens, with reported variations in occurrence across strains and breeds. The aetiology is not fully understood, however, modern genetics and selection for efficient egg production has been claimed to be important factors for the keel bone fractures. To explore this further, we investigated keel bones from two different breeds, representing different degrees of selection for egg production: Red jungle fowl (n = 82), and White Leghorn (n = 32), where the latter is a selected laying breed which is the origin for many modern laying hen hybrids. Keel bones from a total of 116 birds, 53 hens and 63 roosters, were examined by necropsy at 80 weeks of age. All birds were raised in modified aviaries in the same holding facility. Overall, 24.5% of the hens had one or more fractures to the keel, with a difference in the prevalence between hens from the two breeds (p<0.01): 10% (95% CI: 3.7–24%) in the Red Jungle fowl hens and 69% (95% CI: 37–90%) in the White Leghorn hens. No roosters, regardless of breed, had keel bone fractures. Mild to moderate keel bone deviations were present in 54% (95% CI: 25–80%) of the hens and 4.7% (95% CI: 0.5–30%) of the roosters, all White Leghorns.

Preliminary Qualitative Evaluation of the Anatomical Structures for Vocalization in the Chicken (Gallus gallus domestica)

The anatomical structure of phonation in the domestic chicken Gallus gallus (red jungle fowl, forma domestica) of both sexes was studied to determine sex variations in structures. Ten (10) birds, involving 5 males and 5 females were obtained from a local market for student demonstrations and used for this study. Tracheal rings were observed to be made of circular cartilages numbering thirty and above with the distal most (1/5) tracheal rings narrowed, calcified and fused as the tympanum making part of the Syrinx. The rings become calcified and somewhat collapsed through the bronchial bifurcations. When squeezed, the trachea collapsed completely between fingers but could at releasing the fingers be raised up due to elastic components separating the rings from one another. Other structures involved in vocalization includes straps of muscles. Male structures involved in respiration and vocalization were well formed compared to those of the female. Both tracheobronchialis lateralis and ventralis muscles were thicker than those of the female. Male tracheobronchialis ventralis and dorsalis muscles were well formed and spindle shaped. However, the female tracheobronchialis muscles were seen to be wider compared to the male. The vocal organs (voice box) were seen to be arbitrarily triangular in structure at the bifurcation of the trachea in both sexes. The male Syringeal walls were thinner and were seen to have marked inter Pessula space. The Pessulus mark an abrupt change from the circular trachea to strongly elliptical entrances to the bronchi. It was concluded that the differences in the thinness of syringeal walls coupled with differences between the males and females in other tracheal muscles might be responsible for the stronger vocalization in the male.