Academic literature on the topic 'Chicken breeds'
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Journal articles on the topic "Chicken breeds"
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Yu-Shi, Gao, Tu Yun-Jie, Tong Hai-Bing, Wang Ke-Hua, and Chen Kuan-Wei. "AFLP fingerprinting analysis of genetic polymorphism of 12 indigenous chicken breeds." Chinese Journal of Agricultural Biotechnology 4, no. 1 (April 2007): 33–38. http://dx.doi.org/10.1017/s1479236207001234.
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AbstractA total of six amplified fragment length polymorphism (AFLP) primer combinations were used to detect genetic variation of pooled DNA in a sample of 12 chicken breeds indigenous to China, and AFLP DNA fingerprinting of each chicken breed was constructed. Polymorphic bands, specific bands and genetic similarity coefficients of 12 chicken breeds were calculated from AFLP data. A total of 279 polymorphic bands were generated by the six primer combinations, giving, on average, 46.5 polymorphic markers detected per primer combination. Nine specific bands were produced in the pooled DNA of Jiuyuan black and Dongxiang black chickens. However, one specific band was produced in the pooled DNA of Wenchang and Xingyi bantam chickens. An unweighted-pair-group method using average linkages (UPGMA) cluster analysis revealed that the 12 chicken breeds could be divided into three groups. Genetic similarity coefficients and the UPGMA tree of the 12 chicken breeds were consistent with their breeding history as well as their geographical distribution. Based on AFLP DNA fingerprinting, genetic diversity, genetic relationship and identification of chicken breeds can be analysed.
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Yin, Chun Guang, Ding Guo Cao, and Li Xin Du. "Mx Gene Polymorphism in Part Region of Eight Local Chicken Breeds." Applied Mechanics and Materials 108 (October 2011): 297–300. http://dx.doi.org/10.4028/www.scientific.net/amm.108.297.
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In the study, theMxgene promoter, exon 1, exon 2, and exon 14 and intron 13 in eight Chinese local chicken breeds were examined. Amino acid 631 in the GED region was tested in eight Chinese local chicken breeds and two exotic breeds. The frequency of allele A was 0.1259 and the frequency of allele G was 0.8741. Meanwhile, induction of expression of theMxgene in chicken embryo fibroblasts was analyzed in the local chicken breed, Beijing-you and the exotic breed, White Leghorn.The semi-quantitative and quantitative results showed that the expression of theMxgene in White Leghorn was significantly different under different induction conditions. There was also a difference in the genotypic distribution of S631N in two breeds: allele A/G was 0.8471/0.1529 and 0.1613/0.8387 in White Leghorn and Beijing-you chickens, respectively. We speculate that the difference in the genotypic distribution has an effect onMxgene expression.
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Nematbakhsh, Sara, Jinap Selamat, Lokman Hakim Idris, and Ahmad Faizal Abdull Razis. "Chicken Authentication and Discrimination via Live Weight, Body Size, Carcass Traits, and Breast Muscle Fat Content Clustering as Affected by Breed and Sex Varieties in Malaysia." Foods 10, no. 7 (July 7, 2021): 1575. http://dx.doi.org/10.3390/foods10071575.
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Nowadays, the high demand for village chickens in Malaysia leads to the fraudulent substitution of indigenous chickens with other cheaper counterparts. Discriminating different chicken breeds based on their phenotypic characteristics is one strategy to avoid chicken adulteration. The main objective of this study was to authenticate and group dominant chicken breeds in Malaysia, including commercial chickens (Cobb, Hubbard, DeKalb) and cross-bred village chickens (Ayam Kampung, Akar Putra). The further discrimination of village chickens from underaged colored broilers (UCBs) (Hubbard, Sasso) was performed based on phenotype traits. The results showed that the breed had a significant effect (p < 0.05) on phenotypic characteristics, while the sex effect was not significant for some characteristics. In the first phase, the most remarkable discriminating factors were abdominal fat weight, breast muscle weight, chest circumference, shank length, and wingspan. However, in the second phase, notable variations in phenotypic characteristics between village chickens and UCBs were not detected. Principal component analysis (PCA) showed the successful separation of village chickens from high-performance breeds (broiler and colored broiler). Nevertheless, there was overlap among observations for Sasso and village chickens, which approved the possible similarities in their phenotypic characteristics. This study showed clear breed clustering, which leads to the chicken authentication based on their phenotypic characteristics.
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Sartika, Tike, Ferdy Saputra, and Hideaki Takahashi. "Genetic Diversity of Eight Native Indonesian Chicken Breeds on Microsatellite Markers." HAYATI Journal of Biosciences 30, no. 1 (August 29, 2022): 122–30. http://dx.doi.org/10.4308/hjb.30.1.122-130.
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Indonesia has diversity in native chickens based on phenotypes. This diversity is utilized for economic purposes such as meat, eggs, fancy, crowing, and fighting. This study aimed to determine the genetic structure of eight native Indonesian chicken breeds with microsatellite markers, the genetic distance, and inbreeding coefficient of each breed of chicken used for crossbreeding programs to obtain a positive heterosis effect for selection programs. The samples used were Arab, Merawang, Pelung, Sentul, Cemani, KUB, Black Kedu and White Kedu. Broiler chickens (Cobb) were used as the outgroup in this study. A total of 192 DNA samples from eight breeds were used in this study. A total of 24 microsatellite markers were used in this study to observe the genetic diversity of 8 native breeds. The POPGENE, Cervus, and FSTAT were used to generate the observed number of alleles, the effective number of alleles, observed heterozygosity value, expected heterozygosity value, the heterozygote deficit within the breed (FIS), gene flow (Nm), Hardy-Weinberg equilibrium, Polymorphism Information Content (PIC), and UPGMA tree. The principal component analysis (PCA) was performed using adegenet package of R software. Bayesian clustering assignments were analyzed using the STRUCTURE program. This study revealed a very close genetic relationship between seven native chickens and broilers. We also found Arab chickens separated from other Indonesian native chickens and no inbreeding in eight native Indonesian chicken breeds. In conclusion, we found two clusters among eight native Indonesian chicken breeds. Twenty microsatellite markers have a high PIC value in this study.
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Kuma, Berhanu, and Girma Gata. "Determinants of Rural Households’ Poultry Chicken Breeds Choice in Wolaita, Ethiopia." Journal of University of Shanghai for Science and Technology 24, no. 1 (January 9, 2022): 165–85. http://dx.doi.org/10.51201/jusst/21/121056.
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To achieve increased productivity in poultry chicken, households’ choice of poultry chicken breeds should be maintained according to their desirability. This study aimed at identifying determinants of rural households’ choice of poultry chicken breeds keeping in Wolaita, Ethiopia. Multistage sampling techniques were used. First, Damot Pulasa district was selected purposively because of high poultry production potential, and then simple random sampling technique was used to select five kebeles and at third stage systematic random sampling was used to select 160 rural households. Data were collected through interview schedule and analyzed using descriptive statistics and econometric regression. Result showed that 54.37% of households owned indigenous poultry chicken breed, 38% owned exotic poultry chicken breeds and 7.63% owned both indigenous and exotic poultry chicken breeds. Households attached socioeconomic, demographic and institutional factors and breed related traits to their poultry chicken breed choices. Indigenous chicken breeds were preferred in mothering ability, disease resistance, scavenging ability; taste of meat and egg traits whereas exotic poultry chicken breeds were preferred for growth rate, productivity and total eggs laid per chicken per year. In addition, Multinomial Logit model result indicated that age and education level of household head determined poultry chicken breed choice. To be effective and efficient any poultry chicken breed promotion effort in the future should consider these particular preferences of households.
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Zhang, Zeng-Rong, Xiao-Song Jiang, Hua-Rui Du, Xiao-Cheng Li, Qing Zhu, and Yi-Ping Liu. "Tissue-Specific Expression of the Chicken Calpain2 Gene." Molecular Biology International 2010 (August 2, 2010): 1–4. http://dx.doi.org/10.4061/2010/373241.
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We quantified chicken calpain 2 (CAPN2) expression in two Chinese chicken breeds (mountainous black-bone chicken breed [MB] and a commercial meat type chicken breed [S01]) to discern the tissue and ontogenic expression pattern and its effect on muscle metabolism. Real-time quantitative PCR assay was developed for accurate measurement of the CAPN2 mRNA expression in various tissues from chickens of different ages (0, 2, 4, 6, 8, 10, and 12 weeks). Results showed that the breast muscle and leg muscle tissues had the highest expression of CAPN2 compared to the other tissues from the same individual (P<.05). Overall, the CAPN2 mRNA level exhibited a “rise” developmental change in all tissues. The S01 chicken had a higher expression of the CAPN2 mRNA in all tissues than the MB chicken. Our results suggest that chicken CAPN2 expression may be related to chicken breeds and tissues.
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Porimau, Julius, Bercomien J. Papilaya, Muhammad J. Wattiheluw, and Rajab Rajab. "PERFORMA BEBERAPA GALUR AYAM LOKAL FASE GROWER YANG DIPELIHARA PADA TIPE LANTAI KANDANG BERBEDA." Agrinimal Jurnal Ilmu Ternak dan Tanaman 9, no. 2 (April 14, 2022): 101–8. http://dx.doi.org/10.30598/ajitt.2021.9.2.101-108.
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This research aims was to know effect of the interaction between breed and cage floor type factors on the performance of native chickens. The materials used in this study were three breeds of native chickens on grower phase with total number of 72 tails of chicken, an average age was 8 weeks, and an average live body weight was 408.98 grams. The research method used was factorial completely randomized design 3 x 2 x 4. Breeds factor consisting of G1 = Arabian chicken; G2 = Kampung Super, and G3 = Kampong chicken. While the factor of the floor type of cage consists of both L1 = slat floor and L2 = litter floor. Thus there are 6 treatment combinations, each combination treatment were repeated 4 times and each replication consists of 3 chickens, so there are 72 chickens as the unit of observation. The variables observed included feed consumption, drinking water consumption, average daily gain, and feed conversion. The results showed that the interaction between grooves and floor types were not significantly different for all observed variables. Chicken breeds showed significant differences in feed consumption, but did not provide for water consumption, average daily gain and feed conversion. Different cage floors showed the significant difference to feed consumption and drinking water consumption, but there was not significantly different on avegrage daily gain and feed convertion of three breeds of native chicken.
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Porimau, Julius, Bercomien J. Papilaya, Muhammad J. Wattiheluw, and Rajab Rajab. "PERFORMA BEBERAPA GALUR AYAM LOKAL FASE GROWER YANG DIPELIHARA PADA TIPE LANTAI KANDANG BERBEDA." Agrinimal Jurnal Ilmu Ternak dan Tanaman 9, no. 2 (April 14, 2022): 101–8. http://dx.doi.org/10.30598/ajitt.2021.9.2.101-108.
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This research aims was to know effect of the interaction between breed and cage floor type factors on the performance of native chickens. The materials used in this study were three breeds of native chickens on grower phase with total number of 72 tails of chicken, an average age was 8 weeks, and an average live body weight was 408.98 grams. The research method used was factorial completely randomized design 3 x 2 x 4. Breeds factor consisting of G1 = Arabian chicken; G2 = Kampung Super, and G3 = Kampong chicken. While the factor of the floor type of cage consists of both L1 = slat floor and L2 = litter floor. Thus there are 6 treatment combinations, each combination treatment were repeated 4 times and each replication consists of 3 chickens, so there are 72 chickens as the unit of observation. The variables observed included feed consumption, drinking water consumption, average daily gain, and feed conversion. The results showed that the interaction between grooves and floor types were not significantly different for all observed variables. Chicken breeds showed significant differences in feed consumption, but did not provide for water consumption, average daily gain and feed conversion. Different cage floors showed the significant difference to feed consumption and drinking water consumption, but there was not significantly different on avegrage daily gain and feed convertion of three breeds of native chicken.
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Pavlovski, Z., Z. Skrbic, N. Stanisic, S. Lilic, B. Hengl, M. Lukic, and V. Petricevic. "Differences in fatty acid composition of meat between naked neck and two commercial broiler chicken breeds." Biotehnologija u stocarstvu 29, no. 3 (2013): 467–76. http://dx.doi.org/10.2298/bah1303467p.
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Chicken meat from intensive broiler production have different quality compared with meat from native chicken breeds and chicken from a free range production system. The aim of the present study was to evaluate differences in fatty acids content of meat of Naked Neck chickens rared in free range system and two commercial broiler breeds (Cobb 308 and Hybro G+) reared in conventional production system. The trial involved 100 chickens per group. Fattening period lasted 42 days for conventional system and 84 days for free range system. Breast meat of Naked Neck chicken had statistically more 16:0 content compared with Cobb 308 (p?0.05), where in thigh meat the highest content of 16:0 was determined in Hybro G+ breed. Differences for fatty acids composition of breast meat between breeds were also established for 14:0, 17:0, 18:0, 16:1, 18:1, 18:2, 20:2, 22:1 and 22:5 fatty acid. The Naked Neck group showed the highest (p?0.05) percentage of SFA and the Cobb 308 showed the lowest in breast meat. Thigh SFA were also significantly different (p?0.05) between breeds, where Naked Neck chickens had the lowest and Hybro G+ the highest values. Breast MUFA were higher in Hybro G+ than in Naked Neck or Cobb 308 chickens, and thigh MUFA content had opposite trend and it was the lowest in Hybro G+ chicken. In conclusion, free ranged Naked Neck chickens have been shown to have significant different fatty acid composition compared with broiler chickens reared in conventional system.
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Abdi - Soojeede, Mohamed Ibrahim. "Common Somali Indigenous Chicken Breeds, in Mogadishu, Somalia." Integrated Journal for Research in Arts and Humanities 2, no. 4 (July 5, 2022): 38–44. http://dx.doi.org/10.55544/ijrah.2.4.46.
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The main aim of this report is to determine the phenotypic characteristics of Somali indigenous chickens. This research is the initial stage toward a future initiative to differentiate and improve Somali local chicken breeds. There are several indigenous and exotic chicken breeds in Somalia, as well as many other hybrids of chicken; however, this study focused on indigenous breeds that differ in body form, colors, comb type, and capacity to adapt to a given environment in Somalia. The five main indigenous chicken breeds in Somalia. The first indigenous chicken (IC) is Dooro Tiyeglow (Tiyeglow chicken), they have well adapted mostly to agro-pastoral communities’ regions like Bakool region and it has a remarkable beard feather, it also has a single upright comb broad. The second (IC), is Qoordiir (Naked Neck chicken), which is indigenous chicken mostly they have some tassel in the front part of its neck. The prominent plumage color is white and red stripes or red with white strips. Third (IC), is Dooro Jarray (Somali short chicken), this chicken is part of an eco-friendly chicken and is well-known for its small body size. And the common feature of this chicken is black shanks or gray-black shanks. Fourth (IC) is Dooro Buuftoy (Ovambo chickens), this chicken is considered to be smaller in size than exotic chickens, yet it comes in black and red colors. This has a strong personality and is very aggressive. The Fifth (IC) is Dooro Sawahili (Swahili chicken) this chicken is an exotic species that interbreed many local chickens, comes from many angles, has a huge body frame, and is good in egg production. The recommendation of this study is to undertake a government policy to encourage the conservation of Somalia's indigenous chicken breeds in order to prevent extinction and to make development and improvement of local chickens.
Dissertations / Theses on the topic "Chicken breeds"
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Zanetti, Enrico. "Genetic, phenotypic and proteomic characterisation of local chicken breeds." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT010A/document.
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Pour des espèces domestiques communes parmi lesquelles certaines variétés, populations ou races sont menacées d'extinction, le niveau de la population selon laquelle nous devons prendre des mesures est l'objet de recherches dans de nombreux pays. Plusieurs approches ont été développées et utilisées pour comprendre les différents aspects qui contribuent à la différenciation des races et pour l'étude des produits dérivés. Cette thèse se compose de trois contributions. Les objectifs de la première concerne l'étude de la variabilité génétique et l'analyse de la structure de la population dans six races locales italiennes de poulet au sein d’un projet de conservation. On a analysé vingt marqueurs microsatellites dans 337 animaux appartenant à six différentes races: Ermellinata di Rovigo, Robusta Maculata, Robusta Lionata, Pépoi, Padovana et Polverara, une ligne commerciale de poulet a été utilisé comme référence. On a détectés 120 allèles dans l'ensemble de l'échantillon, avec une valeur moyenne de 5.6 plus ou moins 2.1 allèles par locus. Quant aux races locales, l'hétérozygotie observés variaient de 0.240 à 0.413 et celle attendus variaient de 0.243 à 0.463 pour les races Pépoi et Polverara, respectivement. On a observé des écarts de l'équilibre de Hardy-Weinberg pour cinq races ainsi que pour les croisés commerciaux. Dans l'ensemble, la déficience des hétérozygotes dans la population (FIT) résultait 0.427, la valeur moyenne de FIS était de 0.097, tandis que FST était de 0.437, indiquant une forte carence des hétérozygotes due surtout à la division en races. On a utilisé les distances de Reynolds pour dessiner un arbre Neighbor-Joining unrooted, duquel la topologie a fournie des informations sur l’origine génétique de ces races et a confirmé leur histoire connue. La kinship moléculaire estimée entre race variait de 0.559 à 0.769 en mettant en évidence un haut valeur de coancestry. L'analyse de la structure a été réalisée pour mettre en évidence la présence de substructures de la population. Les clusters obtenues séparaient d’une manière nette les animaux en groupes correspondants aux différentes races, sans aucun mélange. L’exception à cette situation étaient les animaux appartenant à la race Polverara, pour laquelle on a rencontré une structure génétique plus complexe. Les résultats ont confirmé l'utilité des marqueurs moléculaires comme les microsatellites, pour la caractérisation des races locales et de monitorage de la diversité génétique dans les programmes de conservation des animaux domestiques. L'objectif de la deuxième contribution a été de décrire les caractéristiques de la carcasse et les caractères qualitatifs de la viande de trois races locales de poulet qui avait, à la maturité, un poids vif moyens, moyen léger et léger. En particulier, l'exploitation commerciale des races étudiées pourraient permettre de développer et de diversifier l'offre aux consommateurs locaux qui ont besoin de différents produits de volaille. L'expérience a impliqué 60 poulets mâles élevés dans un système de production biologique, avec un accès à un espace extérieur avec l'herbe, dans le but d'étudier les caractéristiques de la carcasse et les caractère qualitatifs de la viande de trois races Italiennes avec lente croissance (Ermellinata, Padovana et Pépoi). Les animaux ont été choisis au hasard à éclore, élevés ainsi dans les mêmes conditions et abattus à 190 jours d'âge. Les animaux ont été sectionnés pour mesurer les caractères qualitatifs de la carcasse, après on a analysé des échantillons de poitrine et de cuisse. La race Ermellinata résultait toujours plus lourde que la race Padovana et Pépoi, en ce qui concerne le poids vif, le poids de la carcasse et de la cuisse; en outre, il y avait des différences en ce qui concerne le pourcentage de protéines (Ermellinata > Pépoi et Padovana), la shear force (Padovana < Ermellinata et Pépoi) et cooking loss (Pépoi > Padovana and Ermellinata). Les valeurs de luminosité (L *), l'indice de rouge (a *) et indice de jaune (b *), qui font partie du système de la CIE, montraient une couleur plus claire de viande et plus sombre de peau pour la Padovana par rapport à d’autres races. La composition des acides gras de la poitrine était similaire entre les espèces étudiées, alors que le contenu des acides gras saturés et monoinsaturés dans la race Ermellinata a été respectivement supérieur et inférieur à celui des autres races. Enfin, l’objectif de la troisième contribution a été l’application d’une approche protéomique à l'étude et à la caractérisation des races locales de poulet. L'expriment a impliqué un total de 29 animaux masculins appartenant à des races locales Pépoi, Padovana et Ermellinata di Rovigo. On a analysé des échantillons du muscle pectoral (Pectoralis superficialis). Les fractions contenant la classe de protéines sarcoplasmiques ont été analysés en utilisant l'électrophorèse bidimensionnelle. L'analyse d'image, soutenue par l'analyse statistique, a permis de différencier les individus en groupes selon les similitudes dans l'expression des protéines. Les individus ont été répartis en clusters et en groupes correspondants à la race d’appartenance. L’analyse SAM a permis l'identification du spot plus importante, dont 10 ont été identifiés par spectrométrie de masse en mettant en preuve, bien que préliminaires, les mécanismes des processus qui régissent le processus de différenciation entre les races. Les résultats ont montré une possible utilisation de la protéomique dans le domaine des études concernant la caractérisation de race, et ainsi que dans le domaine de la traçabilité de race ou de produits dérivés, comme une alternative aux analyses génétiques effectuées à travers des marqueurs moléculairesIn common domestic species for which varieties, strains or breeds are in danger of extinction, the population levels at which action needs to be taken are object of research in many countries. Different approaches have been developed and exploited to understand the different aspects that contribute to breed differentiation and to study the typical products that originate from them. The thesis is made up of three contributes. The objectives of the first one were to determine genetic variation and to analyze population structure in six Italian local chicken breeds involved in a conservation program. Twenty microsatellite markers were investigated in 337 animals belonging to six breeds: Ermellinata di Rovigo, Robusta Maculata, Robusta Lionata, Pepoi, Padovana and Polverara; a commercial layer cross was used as reference. One-hundred-twelve alleles were detected in the overall population, with a mean number of 5.6 plus or minus 2.1 alleles per locus. For the local breeds, the observed and expected heterozigosity ranged from a minimum of 0.240 to a maximum of 0.413 and from 0.243 to 0.463 for the Pépoi and Polverara breeds, respectively. Deviation from Hardy-Weinberg equilibrium has been observed in five breeds and in the commercial cross. The overall population heterozygote deficiency FIT, resulted 0.427, the average FIS 0.097, while FST was 0.437, indicating a high heterozygote deficiency mainly due to breed subdivisions. Reynolds distances were used to draw an unrooted Neighbor-Joining tree, which topology gave information on the genetic origin of these breeds and confirmed their known history. The estimated molecular kinship within breed ranged from 0.559 to 0.769, evidencing high coancestry. Structure analysis was performed to detect the presence of population substructures. Inferred clusters corresponded to the different breeds, without presence of admixture. Exception was the Polverara, for which a more complex genetic structure was found. Obtained results confirmed the usefulness of molecular markers, as microsatellites, to characterize local breeds and to monitor genetic diversity in livestock conservation schemes. The objective of the second contribute was to describe carcass characteristics and qualitative meat traits of three local chicken breeds showing, at maturity, light, medium-light, and medium live weights. By the fact, those breeds could permit to extend and diversify consumer’s offer to fit all the local demands in typical diversified poultry products. The experiment involved 60 male chickens reared in an organic production system where housing was an indoor pen with access to a grass paddock was carried out in order to investigate carcass characteristics and qualitative meat traits of three slow-growing Italian local breeds of chicken (Ermellinata, Padovana, and Pépoi). Chicks were randomly selected at hatch, raised together under the same conditions, slaughtered at 190 days of age, dissected for carcass traits and meat was stored for subsequent analysis of breast and thigh meat quality. Ermellinata chickens were consistently heavier than Padovana and Pépoi chickens for live, carcass, thigh weight and there were differences among breeds for protein percentage (Ermellinata > Pépoi and Padovana), shear force (Padovana < Ermellinata and Pépoi), and cooking loss (Pépoi > Padovana and Ermellinata). The CIE system values of lightness (L*), redness (a*), and yellowness (b*) evidenced a distinctive darker and lighter colour of Padovana for meat and skin, respectively. Fatty acid composition of breast was similar among the studied breeds, while saturated and monounsaturated fatty acids contents of Ermellinata were higher and lower, respectively than the other breeds. Aim of the third study was to apply a proteomic approach for characterization of local chicken breeds. The experiment involved a total of 29 males of Pépoi, Padovana, and Ermellinata local chicken breeds. Samples were taken from breast muscle (Pectoralis superficialis). Sarcoplasmic protein fractions of breast muscle were analysed by bidimensional electrophoresis. Image analysis followed by statistical analysis enabled to differentiate groups of individuals on the similarities of protein expression. Individuals were distinguished into clusters and groups, corresponding to the breed of origin. SAM analysis enabled identification of the most relevant spots; 10 of these were identified by Mass Spectrometry revealing preliminary evidences on the mechanics of the breed differentiation process. Results evidenced a possible utilisation of proteomic approach in the field of breed characterization studies as an alternative to genomic analyses performed using molecular markers, both for breed and product traceability purposes
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Grobbelaar, J. A. N., B. Sutherland, and NM Molalakgotla. "Egg production potentials of certain indigenous chicken breeds from South Africa." Animal Genetic Resources, 2010. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001197.
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Summary
The aim of this study was to determine the egg production potentials of four different indigenous chicken breeds in South Africa:
Potchefstroom Koekoek, Venda, Ovambo and Naked Neck. The White Leghorn breed was used as the control. The egg production
potentials were evaluated over two consecutive production cycles of 52 weeks (used as replicates). Data were collected at the experimental
farm of the Agriculture Research Council at Irene. Treatment means were separated using Fisher’s protected t-test least significant
difference at the 5 percent level of significance and the percentage mortality rate by means of a row by column chi-square test. No
significant differences were observed between breeds on the mean age to the production of the first egg. The White Leghorn was
superior ( p ≤ 0.05) to all four of the indigenous breeds for the mean number of eggs and percentage hen-housed egg production produced
per production cycle. The Potchefstroom Koekoek was also superior ( p ≤ 0.05) to the other three indigenous breeds for these
parameters. There was no difference between the Ovambo and Naked Neck breeds. The percentage mortality rate for the White
Leghorn (39.5 percent) was significantly ( p ≤ 0.05) different from that of the Venda, Ovambo and Potchefstroom Koekoek (22.2 percent).
No differences were observed among the Potchefstroom Koekoek, Venda, Ovambo and Naked Neck (32.3 percent) or between
the White Leghorn and Naked Neck with regard to the mean percentage mortality.
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Makhafola, Maila Bervly. "Correlations between live performance and reproductive traits of South African indigenous male chicken breeds." Thesis, [Bloemfontein?] : Central University of Technology, Free State, 2013. http://hdl.handle.net/11462/159.
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Thesis (M. Tech. (Agriculture)) - Central University of Technology, Free state, 2013The objectives of the study were to find the relationship between live performance and testis traits of South African indigenous cockerels on Naked Neck, Ovambo and Potchefstroom Koekoek (Trial 1). Characterise Naked Neck, Ovambo and Potchefstroom Koekoek cockerels’ semen macroscopically and microscopically (Trial 2). To investigate the relationship between phenotypic and sperm traits of the South African indigenous cockerels Naked Neck, Ovambo and Potchefstroom Koekoek. (Trial 3). Quantification of indigenous cockerels sperm traits measured by Computer Assisted Sperm Analysis (CASA) technology and the relationship to fertility (Trial 4). The cockerels shank, comb and wattle length were recorded with a vernier calliper. A total of 198 ejaculates were collected from 33 cockerels; Ovambo (n=11), Potchefstroom Koekoek (n=11) and Naked Neck (n=11) by means of an abdominal massage technique. Following analysis, 0.25 ml undiluted semen dose from Naked Neck (NN, 11), Ovambo (OV, 11) and Potchefstroom Koekoek (PK, 11) cockerels were inseminated NN (30), OV (30) and PK (30) hens once per week for 6 weeks. Semen was analysed macroscopically and microscopically. The sperm motility rate was evaluated with the aid of the Computer Assisted Sperm Analysis (CASA) called Sperm Class Analyser (SCA) system. Breed significantly (P< 0.05) affected the body weight of Ovambo (2.5±0.4kg), Naked Neck (2.0±0.3kg) and Potchefstroom Koekoek (2.3±0.3kg) cockerels, OV was statistically heavier than NN and PK. The semen volume of Naked Neck (0.5±0.2ml) breed was significantly higher, when compared to Ovambo (0.4±0.2ml), but similar to Potchefstroom Koekoek (0.3±0.2ml) breed. The overall sperm motility rate of Ovambo (95.0±7.2%), Potchefstroom Koekoek (86.0±13.7%) Naked Neck (76.4±22.2%) group was significantly different. The normal sperm morphology in the Naked Neck (76.4±22.2%) was significantly lower when compared to Potchefstroom Koekoek (86.0±13.7%) and Ovambo (95.0±7.2%) cockerels. A positive correlation existed between body weight and semen volume for Potchefstroom Koekoek (r=0.1477) cockerels only. Moreover, there was a positive correlation between the body weight and total sperm motility for Naked Neck (r=0.3848), Ovambo (r=0.4871) and Potchefstroom Koekoek (r=0.2230) cockerels. However, a negative correlation existed between body weight and semen volume for Naked Neck (r=-0.4502) and Ovambo (r=-0.1244). There was no significant differences (P>0.05) on the shank length (SL), comb length (CL) and wattle length WL) of Naked Neck (8.4, 5.4 and 5.6 cm), Ovambo (8.3, 5.8 and 6.0 cm) and Potchefstroom Koekoek (7.7, 5.9 and 5.6). There was a positive correlation between shank length and wattle length, comb length, semen volume, sperm concentration, semen pH and live normal sperm, inversely, a negative correlation of body weight and total sperm motility was observed. Introspective a negative correlation existed between body weight and total motility. Ovambo (11.45±0.9 g) had the highest live weight of testis, it was significantly different from Naked Neck (9.2±0.8g) and Potchefstroom Koekoek (8.9±0.8 g). For average length of the testis there was a significant difference amongst all breeds, Ovambo (4.0±0.5 cm), Naked Neck (3.4±0.3 cm) and Potchefstroom Koekoek (3.7±0.4 cm). Following Al, significant differences were recorded in Potchefstroom Koekoek and produced eggs that had highest average egg weight (55.5 g), fertility (68.2 %), hatchability (78.6 %), percentage of normal chicks (80.1%) and chick weight (37.9 g) compared to Ovambo (40.4 g, 5 2.1 % , 70.2 %, 71.5 %, 32.8 g and Naked Neck (37.1 g, 50.6 %, 71.1 %, 75.8 % and 23.5 g). In order to achieve the highest level of fertility and hatched of fertile eggs, an adequate number of active males that are producing high quality semen should be maintained in the breeder house at all times. In conclusion, body weight positively affected semen volume and sperm motility rate but this was breed dependent. The Sperm of Potchefstroom Koekoek and Ovambo resulted in a better motility and morphology rate. The Sperm Class Analyser or CASA provided more precise, repeatable and objective information. Evaluation of the sperm motility rate of South African indigenous cockerels holds potential for future use in semen evaluation. Body weight of all three indigenous breeds was positively correlated with sperm concentration, semen pH, and total sperm motility. Shank and wattle length of all three indigenous breeds were positively correlated with semen volume, sperm concentration, and semen pH but not with total sperm motility. However, comb length was positively correlated with semen volume and pH, sperm concentration, and total motility. In conclusion, there is no correlation between live performance and testis traits. Though the study suggests that body weight and testicular length are good indicators of sperm production. Simple and indirect method of estimation is still needed to predict the fertility of the breeding cockerels. In order to achieve the highest level of fertility and hatch of fertile eggs, an adequate number of active males that are producing high quality semen should be maintained in the breeder house at all times. The Potchefstroom Koekoek, Ovambo and Naked Neck donated quality semen as well as in improving the fertility and hatchability traits of the indigenous chicken breeds. Chicken hatched from larger eggs had higher body weight, hatchability and fertility therefore breeders should select bigger egg sizes probably of 50-55g for breeding programmes. Consequently, the local cockerels have higher potential for use in natural mating and Al programmes since seminal traits could be a viable index for selection of breeding cockerels.
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Mbajiorgu, Christian A. "Effect of time of initiation of feeding after hatching and influence of dietary lysine and ascorbic acid supplementation on productivity and mortality of Ross 308 broiler chickens." Thesis, University of Limpopo (Turfloop Campus), 2007. http://hdl.handle.net/10386/692.
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Thesis (M.Sc. (Animal Production)) --University of Limpopo, 2007Two experiments were conducted to evaluate the effect of time of initiation of feeding after hatching and influence of dietary lysine and ascorbic acid supplementation on productivity, carcass characteristics and mortality of Ross 308 broiler chickens. The first experiment examined the effect of time of initiation of feeding after hatching and influence of dietary lysine supplementation during realimentation on productivity, carcass characteristics and mortality of Ross 308 broiler chickens during the winter period. Three hundred and sixty unsexed Ross 308 broiler chickens with an initial weight of 30 ± 2 g per bird were assigned to twelve treatments with three replications of ten birds each in a 4 (times of initiation of feeding) x 3 (lysine supplemental levels) factorial, complete randomized design. At each time of initiation of feeding after hatching during the starter and grower stages, the diets were isocaloric and isonitrogenous but with three different lysine supplementation levels. Lysine supplementation started three days after hatching. Time of initiation of feeding above 36 hours after hatching resulted in growth retardation and high mortality rate. More than 50 % of the birds died between one and three days of age when initiation of feeding after hatching was above 36 hours. However, the birds ‘caught-up’ at the latest within eight days of realimentation. This compensatory growth could be explained in terms of higher intakes. Lysine supplementation during realimentation reduced the number of days of ‘catch-up’ irrespective of time of initiation of feeding after hatching. Generally, the higher the level of lysine supplementation, the lower was the number of days of ‘catch-up’ upon realimentation. Thereafter, time of initiation of feeding after hatching and lysine supplementation had no effect (P>0.05) on live weight, feed intake, growth rate, feed conversion ratio, diet digestibility, nitrogen content of breast meat, dressing %, carcass characteristics and mortality of Ross 308 broiler chickens. The second experiment examined the effect of time of initiation of feeding after hatching and influence of dietary ascorbic acid supplementation on productivity, carcass characteristics and mortality of Ross 308 broiler chickens during the summer period. Six v hundred and seventy five unsexed Ross 308 broiler chickens with an initial weight of 32 ± 2 g per bird were assigned to fifteen treatments with three replications of fifteen birds each in a 3 (times of initiation of feeding) x 5 (ascorbic acid supplemental levels) factorial, complete randomized design. Ascorbic acid supplementation started 3 days after hatching. An average of 18 % and 31 % of the birds died between one and three days of age when initiation of feeding after hatching was above 36 hours. However, the birds ‘caught-up’ within ten days of realimentation irrespective of time of initiation of feeding after hatching. This compensatory growth could be explained in terms of reduced maintenance requirement and possibly, increased efficiency of growth. Following ‘catch-up’, ascorbic acid supplementation during realimentation lowered (P<0.05) mortality rate and improved growth rates irrespective of time of initiation of feeding after hatching. Growth rate increased incrementally with increasing levels of ascorbic acid supplementation within each time of initiation of feeding after hatching. Improved growth rate in the ascorbic acid supplemented birds resulted in improved live weight in comparison with those without ascorbic acid supplementation at 21 days of age and continued until 42 days of age. Live weight increased incrementally with increasing levels of ascorbic acid supplementation within each time of initiation of feeding after hatching. Similarly, increasing ascorbic acid supplementation within each time of initiation of feeding after hatching increased dressing percentage and breast meat yield at 42 days old. However, ascorbic acid supplementation had no effect (P>0.05) on feed intake of the birds irrespective of time of initiation of feeding after hatching. In both experiments, mortality was positively and strongly correlated with time of initiation of feeding after hatching while live weight was negatively and strongly correlated with time of initiation of feeding after hatching. It is concluded that time of initiation of feeding above 36 hours after hatching is not desirable, mainly because of its effect on mortality. However, lysine supplementation in the diet of broiler chickens subjected to delayed initiation of feeding after hatching might play a key role in accelerating the rate of ‘catch-up’ growth response. vi It is also concluded that the beneficial effect of ascorbic acid supplementation could be exploited in reducing mortality rate and improving growth rates in broiler chickens subjected to delayed initiation of feeding after hatching.
the National Research Foundation
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Foster, Alison. "Identifying chicken breeds in the archaeological record : a geometric and linear morphometric approach." Thesis, University of Leicester, 2018. http://hdl.handle.net/2381/42780.
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Domestic fowl remains are a small but significant element of many post-Iron Age bone assemblages, reflecting the importance of the many roles of this species, whether in augury, entertainment or different aspects of food-production. Size and shape variation in archaeological chicken bones has long been recognised as a possible indicator of different breeds or types associated with these roles, implying selection for favourable characteristics and the development of specialisation in poultry-keeping. This study investigates the potential of shape-analysis for identifying bone shape variation that may characterise particular morphotypes, helping to elucidate the processes of domestication and selection and the means and motivations behind breed development. The thesis explores the potential for geometric morphometrics to complement traditional biometrical analysis in identifying osteological differences in domestic fowl remains. By focusing on shape independent of size, GMM offers a new approach, identifying subtle variations in bone morphology which would not otherwise be detected. GMM techniques were applied to selected post-cranial bone elements from modern domestic fowl of known-breed, age and sex, revealing consistent morphological similarities and differences in some breeds. These methods were then applied to archaeological elements from Romano-British, Anglo-Saxon and Early Modern deposits, with the aim of identifying progressive breed development within this wide chronology. Analysis of linear metrical data from the same modern and archaeological material enabled comparisons to be made between the two techniques. The findings support the use of both measurement ratios and GMM methods for determining breed-related variation in selected chicken elements and suggest a strong potential for extending the research using additional bone elements and 3D imaging techniques.
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Thabo, Molekwa Julian. "Relationships between cock semen viability and the fertility of artificially inseminated South African indigenous chicken breeds." Thesis, [Bloemfontein?] : Central University of Technology, Free State, 2007. http://hdl.handle.net/11462/106.
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Thesis (M. Tech.) -- Central University of Technology, Free State, 2007Four different South African indigenous (Naked Neck (NN), Ovambo (OVB), Venda (VD) and Potchefstroom Koekoek (PK) chicken breeds were used in this study. From each of the four breeds of chicken, 40 hens and 8 cocks were selected randomly. Two groups each of sixteen cocks were subsequently formed: high performing (HP) and low performing (LP) groups to determine the relationships between cock semen viability and the fertility of artificially inseminated South African indigenous layer breeds. Semen was collected following five minutes of sexual massage (5SM) and evaluated for semen volume (ml), sperm motility (%), live sperm (%) and total sperm (x109/ml). Semen from each cock was then used to inseminate five hens per breed, in each treatment. Each hen was inseminated twice a week throughout the duration of the trial. During the experimental period, each hen was inseminated with 0.05 ml diluted semen. The artificially inseminated hens were examined for average egg weight (g), fertility (%), hatchability of set eggs (%), live chicks (%), normal chicks (%) and chick weight (g). A total of 1600 eggs, i.e. 400 eggs from each breed were collected in three batches following artificial insemination from individually caged hens and were hatched to compare hatching parameters among breeds. The hatchability traits of hens of the four breeds (NN, OVB, PK and VD) were compared. Hatching egg weight had significant (P < 0.05) difference among the four breeds. The results of this study indicate that semen viability exemplified by ejaculate volume, sperm motility; live sperm and total sperm per ejaculate were significantly (P < 0.01) superior in the HP cocks compared to the LP cocks. Hens inseminated with semen from the HP cocks in each experimental group resulted in higher egg weight (g), fertility (%), hatchability of set eggs (%), live chicks (%), normal chicks (%) and chick weight (g). Significant positive relationships existed between semen volume and sperm motility (P < 0.05), semen volume and live sperm cells (P < 0.01), semen volume and total sperm (P < 0.01) in NN, OVB and VD, with negative correlations in PK. Some positive correlations were found between sperm motility and live spermatozoa (P < 0.01), sperm motility and total sperm (P < 0.01), live sperm and total sperm (P< 0.01) in NN, OVB, PK and VND. Fertility was the highest in the HP group. Fertility was also the highest in PK, intermediate and similar in OVB and NN and lowest in VD (P<0.05). Breed had a significant effect on hatchability of fertile eggs (P<0.05). Hatchability of total eggs set was highest in PK and NN, intermediate in OVB and lowest in VD (P<0.05). Breed had a significant effect on live, normal chicks and chick weight (P<0.05). Live chick was the highest in NN, whereas at day-old, normal chick and chick weight at hatching were the highest (23.50 ± 0.11) (P<0.05) in PK (98.14 ± 0.67 vs. 37.90 ± 0.28 g), intermediate and similar in NN (87.90 ± 0.63 vs. 23.50 ± 0.11) and OVB (87.75 ± 0.45 vs. 32.81 ± 0.49 g) and the lowest but with an acceptable value in VD (76.85 ± 0.46 vs. 26.90 ± 0.36 g). There were some correlations among different hatchability traits depending on breed. The correlations were more profound among PK. It was clear that chick weight as percent of egg weight was not just a function of egg weight, and that genotype also played an important role favouring the heavier breeds. The results obtained in this study on the relationships between cock semen viability and the fertility of artificially inseminated South African indigenous layer breeds elucidate that the use of high performing (HP) cocks following five minutes of sexual massage, prior to semen collection and artificial insemination of layers is a practical method for optimising sperm viability and subsequent fertility of hens. The results of this study suggest that the Potchefstroom Koekoek (PK) cocks and hens are superior to the Naked Necks (NN), Ovambo (OVB) and Venda (VD). The Ovambo and Naked Neck cocks ranked second in donating quality semen as well as in improving the fertility and hatchability traits of the indigenous chicken breeds. Thus selection of high performing cocks through five minutes sexual massage prior to semen collection and use is recommended for poultry AI breeding programmes.
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Cid, Joana Filipa Santos. "Características físicas e químicas de ovos produzidos por galinhas de raças portuguesas." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2017. http://hdl.handle.net/10400.5/14030.
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Dissertação de Mestrado em Engenharia Zootécnica/Produção AnimalEste estudo teve como objetivo analisar a variabilidade das características físicas e químicas dos ovos das raças autóctones de galináceos e compará-las com os ovos de uma estirpe comercial. Foram utilizados 286 ovos das quatro raças autóctones e da estirpe Tetra, provenientes de 15 explorações diferentes, os quais foram analisados entre os 8 e os 15 dias após ovoposição. Todos os ovos analisados após os oito dias foram refrigerados. Analisaram-se diversos parâmetros físicos dos ovos e dos seus componentes, tais como pesos, pH, unidades Haugh, cor da gema e cor da casca, shape index, yolk index, altura da câmara de ar, viscosidade da clara e presença de manchas de carne, de sangue e de fendas na casca. Procedeu-se também à análise de características químicas: conteúdo proteico da clara, a composição de ácidos gordos da gema e a composição de minerais na gema e na clara. Pelos resultados obtidos, verificou-se que os ovos da raça Branca são mais pesados, com maior área superficial, casca com um tom de castanho mais claro e menor valor de unidades Haugh em relação aos ovos das restantes raças autóctones. A estirpe Tetra produz ovos com maior peso, maior área superficial e menor valor de unidades Haugh do que as raças Amarela, Pedrês Portuguesa e Preta Lusitânica. A estirpe Tetra produz ovos mais arredondados que o ideal, com casca mais castanha e gema mais alaranjada do que as quatro raças autóctones.
ABSTRACT - Physical and chemical characteristics of eggs from Portuguese indigenous chicken breeds - This study aimed to characterize the variability among Portuguese indigenous breeds of hens and to compare them with a commercial hybrid hens (Tetra), regarding their egg quality, through analysis of their physical and chemical characteristics. A total of 286 eggs from the four native breeds and from the commercial hybrid hen were obtained from 15 different farms, and analysed 8 to 15 days after oviposition. All eggs analysed 8 days after oviposition were refrigerated. Various physical parameters of the eggs were analysed, such as weight, pH, Haugh units, shell and yolk colour, shape index, yolk index, air cell height, viscosity, blood and meat spots and shell cracks. The chemical characteristics analysed were albumen protein, yolk fatty acid profile and the composition of minerals in the yolk and albumen. The results indicated that Branca’s eggs have larger weight and surface area, a lighter eggshell and a lower value of Haugh units than the eggs of the other Portuguese indigenous breeds. The commercial hybrid hen produces eggs with larger weight and surface area and lower value of Haugh units in relation to the Portuguese autochthonous chickens, such as Amarela, Pedrês Portuguesa and Preta Lusitânica. The commercial hybrid hen produces more rounded eggs than the ideal, with a brownish eggshell and a more orange yolk than the four Portuguese autochthonous breeds.
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Gholami, Mahmood Verfasser], Henner [Akademischer Betreuer] [Simianer, Steffen [Akademischer Betreuer] Weigend, and Christoph [Akademischer Betreuer] Knorr. "Selection signature detection in a diverse set of chicken breeds / Mahmood Gholami. Gutachter: Steffen Weigend ; Christoph Knorr. Betreuer: Henner Simianer." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/106588253X/34.
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Malomane, Dorcus Kholofelo [Verfasser], Henner [Akademischer Betreuer] Simianer, Steffen [Gutachter] Weigend, and Armin [Gutachter] Schmitt. "Retrieving patterns of genetic diversity in a global set of chicken breeds / Dorcus Kholofelo Malomane ; Gutachter: Steffen Weigend, Armin Schmitt ; Betreuer: Henner Simianer." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1204255989/34.
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Hanyani, Charles Tawanda. "Effect of full and semi-scavenging rearing systems on crop contents and the quality of meat from village chickens during spring season of Eastern Cape, South Africa." Thesis, University of Fort Hare, 2012. http://hdl.handle.net/10353/440.
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The objective of this study was to compare the nutrient status of full scavenging and semi-scavenging village chicken production systems. The semi-scavenging chickens were given broiler finisher mash between 14-24 weeks of age, whilst the full scavenging relied on natural foraging. The study also sought to compare the quality of meat from chickens from the two systems. After slaughtering the chickens, the crop contents were physically separated and analysed for chemical composition. Meat pH and colour were measured on the breast muscle of individual carcasses and a consumer sensory evaluation was also done on the breast muscle. The mean crop content weights per day were significantly higher in full scavenging chickens (±16.7g/day biomass) than in semi-scavenging chickens (±9.14g/day). Dry matter, calcium, and phosphorus levels were higher in the crop contents of the full than in the semi-scavenging chickens but crude protein, crude fibre and metabolisable energy were higher in the latter system. Semi-scavenging (1.3 ± 0.05kg) carcasses were heavier (P<0.05) than full scavenging ones (1.0 ± 0.06kg). The ultimate pH (24h) (pHu) of meat from full scavenging chickens (6.0 ± 0.03) was higher (P<0.05) than that of meat from the semi-scavenging chickens (5.7 ± 0.04). Meat from the full scavenging chickens had higher L* values (60 ± 1.2) than meat from the semi-scavenging chickens (47 ± 0.8). The a* value of meat of full scavenging chickens was significantly (P<0.05) less (4 ± 0.4) than that of meat from semi-scavenging chickens (15 ± 1.3). There was a significant positive (0.60) correlation between pHu and L* of meat from village chickens across rearing systems. The semi-scavenging system meat had better sensory attributes than the meat from the full scavenging system. Female consumers scored the typical flavour of village chicken meat across rearing systems higher (P< 0.05) than male consumers. The Shona consumers scored the meat higher (P< 0.05) than the Xhosa, Zulu, Ndebele and other tribes for initial juiciness, first bite impression and muscle fibre and tenderness of the chicken across rearing systems. Consumers scored of the meat from the semi-scavenging system higher (P<0.05) on initial juiciness (4.3 ± 0.20), first bite impression (4.2 ± 0.197), muscle fibre tenderness (4.5 ± 0.217) than meat from the full scavenging chickens. There were positive correlations (0.46) between aroma intensity and overall flavour intensity across both rearing systems. The semi-scavenging system produced better carcass characteristics, lighter (L*) meat and more consumer acceptable meat than full scavenging chickens. Therefore the full scavenging rearing system had better nutrient composition in its scavenging feed resource base, although the semi-scavenging systems produced chickens with better carcass, meat pH, colour and sensory characteristics than the full scavenging chickens.
Books on the topic "Chicken breeds"
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Bassom, Frances. Chicken breeds & care: A color directory of the most popular breeds and their care. Buffalo, N.Y: Firefly Books, 2009.
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The illustrated guide to chickens: How to choose them : how to keep them. New York: Metro Books, 2010.
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Chicken breeds & care: A color directory of the most popular breeds and their care. Buffalo, N.Y: Firefly Books, 2009.
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Kemp, Rick. Exhibition poultry breeder's handbook. Kenthurst, NSW: Kangaroo Press, 1989.
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Stephen, Green-Armytage, ed. Extra extraordinary chickens. New York, N.Y: H.N. Abrams, 2005.
Find full textBook chapters on the topic "Chicken breeds"
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Bell, Donald D. "Modern Breeds of Chickens." In Commercial Chicken Meat and Egg Production, 31–40. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0811-3_3.
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Kozikova, Larisa, and Ekaterina Polteva. "Phenotypic Features of the Chicken Chimeras Obtained by Transplantation of Blastoderm Cells of the Russian White, New Hampshire and Australorp Black Breeds." In Fundamental and Applied Scientific Research in the Development of Agriculture in the Far East (AFE-2021), 561–69. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-91405-9_62.
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Coon, Craig N. "Feeding Broiler Breeders." In Commercial Chicken Meat and Egg Production, 329–69. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0811-3_19.
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Rege, J. E. O., Joel Ochieng, and Olivier Hanotte. "Livestock genetics and breeding." In The impact of the International Livestock Research Institute, 59–102. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789241853.0059.
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Abstract This chapter describes the contributions of the International Livestock Research Institute's (ILRI) to animal breeding. The specific topics include the genetic characterization and history of livestock, breeding technologies, genetic improvement of indigenous livestock, tools and methods for conducting breed surveys, classification of African livestock populations, molecular genetic characterization, the genetic history of cattle in Africa and linking livestock to human history, genetic history and geography of African sheep, genetic history and geography of African chickens, genetic history and geography of the African dromedary, establishment of a joint laboratory with CAAS in Beijing and expansion into Asia, ILRI's genetic characterization as a catalyst for international interest, genetics of trypanotolerance and genetics of resistance to gastrointestinal parasites.
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Variath, Murali T., Sunil Chaudhari, Srinivas Samineni, Dnyaneshwar B. Deshmukh, Anand Kannati, and Sudarshan Patil. "Genomic Selection in Groundnut, Chickpea, and Pearl Millet: Applications and Prospects." In Genomic Selection in Plants A Guide for Breeders, 83–110. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003214991-5.
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"CHAPTER 5. Breeds." In The Chicken, 155–212. Princeton University Press, 2018. http://dx.doi.org/10.1515/9780691184562-006.
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Alsoufi, Mohammed, and Ge Changrong. "Genetic Diversity and Evolution of Yunnan Chicken Breeds of China." In Population Genetics [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102915.
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Chickens are the first type of bird that was domesticated and spread widely in the world to cover the growing demand for animal protein from meat and eggs, and it was cultivated from a wild ancestor known Red junglefowl (Gallus gallus). Yunnan Province is considered the most diverse in culture and biology among all the provinces of China. There are a total of more than 24 chicken breeds in Yunnan Province. These chickens are characterized by good quality of their meat and eggs, a good immune system against diseases, and the ability to adapt to various environmental and administrative conditions. Yunnan Province is one of the centers of domestication and evolutionary of chickens in the world. There are many studies that have been conducted to evaluate and study the genetic diversity and evolutionary relationship within and among chicken breeds in Yunnan Province and their relationship with wild chicken species and other chicken breeds using phenotypic markers, protein polymorphisms, SNPs marker, microsatellite marker, and mitochondrial DNA marker. However, there is no review that summarizes these studies, and most of these studies were authored in the Chinese language. Therefore, we have reviewed all studies that have been conducted on Yunnan chicken breeds diversity in Yunnan Province.
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Han, Ruili, Zhuanjian Li, Yaping Guo, and Xiangnan Wang. "Detection and Utility of Genetic Variation in Chinese Local Chicken Breeds." In Application of Genetics and Genomics in Poultry Science. InTech, 2018. http://dx.doi.org/10.5772/intechopen.77028.
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Bao, Yiqin, and Yulu Bao. "Chicken and Egg Food Traceability System Based on NFC and QR Code Technology." In Frontiers in Artificial Intelligence and Applications. IOS Press, 2022. http://dx.doi.org/10.3233/faia220534.
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Chicken and egg food traceability system based on NFC and QR code technology was designed. The traceability system registers and uploads the information of raised chickens through the chicken foot ring embedded with NFC tag. The system generates egg QR code according to the registered information and prints it on the eggs corresponding to the raised chickens. It is used for consumer users to scan and query the relevant information of the eggs and the raised chickens, including the breeding address, breeder and breeding record of the raised chickens. The system is designed based on the classic three-layer mode of the Internet of things and the B / S architecture. The system mainly realizes the traceability of chickens through NFC tags and eggs through QR codes. It has high stability and great application and promotion value.
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van Emous, Rick, and André Steentjes. "Optimizing the health of broiler breeder birds." In Optimising poultry flock health, 347–86. Burleigh Dodds Science Publishing, 2022. http://dx.doi.org/10.19103/as.2022.0104.13.
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The main objective in broiler breeder production is to produce fertilized eggs resulting in healthy and robust day-old broiler chicks. Due to the continuing increase in the genetic potential of the offspring and the improved reproduction performance, there is a high need for professional management and poultry health care of broiler breeder flocks. Implementation of strict biosecurity measures in combination with intensive, well-orchestrated vaccination programs must prevent disease challenges for both breeders and offspring. Points of attention during the rearing period are stress factors like necessary feed restriction, flock density, bird handling, transport and vaccination reactions. A good coordination between rearing and laying period in equipment, management, feed strategy and health care is crucial for maximum chick performance. This chapter gives an overview of the diseases, vaccinations and direct and indirect effects of management and nutritional interventions on health and productivity in broiler breeders.
Conference papers on the topic "Chicken breeds"
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Adli, Danung Nur, and Osfar Sjofjan. "Modelling Egg Production of New-Kampong Crossbreed Chicken (KUB) as Promotion of Indigenous Chicken Breeds Using Three Mathematical Methods." In 6th International Seminar of Animal Nutrition and Feed Science (ISANFS 2021). Paris, France: Atlantis Press, 2022. http://dx.doi.org/10.2991/absr.k.220401.031.
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Turganbaeva, A. S. "Influence of water concentration on the content of protein and nucleic acids in organs of chick embryos of different ages." In VIII Vserossijskaja konferencija s mezhdunarodnym uchastiem «Mediko-fiziologicheskie problemy jekologii cheloveka». Publishing center of Ulyanovsk State University, 2021. http://dx.doi.org/10.34014/mpphe.2021-191-194.
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The study was carried out in 10-, 14-15-, 18-20-day-old embryos and 1-2-day-old chickens of the Hy-Line breed. In chickens during embryogenesis, the peculiarities of the relationship between the main indicator of the ontogenetic growth of organs and tissues - the content of intracellular water by previously measured values: with the concentration of protein and nucleic acids in the organs of chicken embryos of different ages - were assessed.
It was found that in the period of 10-19 days of embryogenesis, the growth of organs is accompanied by a significant decrease in water content to varying degrees: noticeably higher in the liver and in the cerebral hemispheres - up to 14 days; from the 19th day, these changes are less pronounced. The results of the studied indicator in the muscles indicate advanced embryonic development with a more pronounced decrease in the water content in the red oxidative muscles in comparison with white muscles, where the decrease in the indicator is less pronounced.
Key words: chicken embryos, protein, nucleic acid, water content, pectoralis alba and gastrocnemius muscle.
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Suariani, Luh, Ni Ketut Suwitari, and Ni Yudiastari. "Disability and Nitrogen Retention of Native Chicken Returns That Contain Bread Flour." In Proceedings of the 3nd Warmadewa Research and Development Seminar, WARDS 2020, 21 December 2020, Denpasar-Bali, Indonesia. EAI, 2021. http://dx.doi.org/10.4108/eai.21-12-2020.2305844.
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Trukhachev, Vladimir, Elena Epimahova, Vitaly Morozov, and Andrey Vrana. "Hatchability prediction in Ross-308 cross-bred broiler chickens." In 16th International Scientific Conference Engineering for Rural Development. Latvia University of Agriculture, 2017. http://dx.doi.org/10.22616/erdev2017.16.n190.
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Petcu, Igor, Ion Balan, Boris Demcenco, Natalia Osadci, Feodora Rosca, and Veaceslav Gramovici. "Influence of lighting modes on the age of puberty and egg laying chickens." In XIth International Congress of Geneticists and Breeders from the Republic of Moldova. Scientific Association of Geneticists and Breeders of the Republic of Moldova, Institute of Genetics, Physiology and Plant Protection, Moldova State University, 2021. http://dx.doi.org/10.53040/cga11.2021.109.
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Dürdane, Mart, and Türkeri Meltem. "Food legumes breeding program in eastern Mediterranean region and Turkey." In VIIth International Scientific Conference “Genetics, Physiology and Plant Breeding”. Institute of Genetics, Physiology and Plant Protection, Republic of Moldova, 2021. http://dx.doi.org/10.53040/gppb7.2021.97.
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Breeding is aimed to breed for varieties that are tolerant against disease, suitable for mechanized cultivation and harvest, and also offer them to the farmers as promising varieties. Since the purpose of legumes production is to obtain grain products of high yield and quality, developing suitable varieties for target regions where they will be grown is an important factor that needs to be considered. This breeding program aimed to develop new variety of recommended legumes varieties for different regions and will stimulate an increase in cultivation area. In Turkey chickpea is traditionally sown in spring and subjected to drought and heat stresses. Chickpea can be sown in autumn with new cultivars but winter-sown chickpea cultivars are not available for highlands. Some abiotic stresses (drought, heat, freezing etc.) and some biotic stresses (ascochyta blight, Fusarium wilt, and weeds) are common and important stresses, whereas nutrient imbalance includ-ing salinity are localized challenges. Lentil is usually traditionally sown in autumn and Central Anatolia green lentil, South Eastern Anatolia red lentil regions in Turkey. As a result of Turkish food legume Program, 48 chickpea, 41lentil, 49 beans, 3 faba beans, 3 pea and 4 cowpea varieties were registered.
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"Body Weight of Kampung Unggul Balitbangtan Chicken Reared in Two Farmers Groups in the Brebes Regency." In Technology Innovations and Collaborations in Livestock Production for Sustainable Food Systems. IAARD Press, 2021. http://dx.doi.org/10.14334/proc.intsem.lpvt-2021-p.13.
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Indi, Amiluddin, Deki Zulkarnain, Yamin Yaddi, and Asriamin Mursadat. "The Potential of Broiler Chicken Development: A Case Study of Broiler Breeders in Kambu District, Kendari City." In International Conference on Improving Tropical Animal Production for Food Security (ITAPS 2021). Paris, France: Atlantis Press, 2022. http://dx.doi.org/10.2991/absr.k.220309.013.
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Rafaelle Maciel Guimarães, Mylena, JOSE LUIS RAMIREZ ASCHERI, Marilia Penteado Stephan, Jhony Willian Vargas-Solórzano, and Carlos Wanderlei Piler de Carvalho. "EFFECT OF THE EXTRUSION PRECOOKING AND CHICKPEA FLOUR ADDITION ON GLUTEN-FREE AND VEGAN BREADS." In II CBCP - Congresso Brasileiro de Tecnologia de Cereais e Panificação. ,: Even3, 2022. http://dx.doi.org/10.29327/cbcp2022.516939.
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Curshunji, Dmitrii. "Evaluation the breeding material of chickpea for yield, biotic stress and characteristics some morphobiological traits." In XIth International Congress of Geneticists and Breeders from the Republic of Moldova. Scientific Association of Geneticists and Breeders of the Republic of Moldova, Institute of Genetics, Physiology and Plant Protection, Moldova State University, 2021. http://dx.doi.org/10.53040/cga11.2021.064.
Full textReports on the topic "Chicken breeds"
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Elbetagy, Ahmed R., Francesca Bertolini, Damarius S. Fleming, Angelica G. Van Goor, Carl Schmidt, Susan J. Lamont, and Max F. Rothschild. Evidence of Natural Selection Footprints Among Some African Chicken Breeds and Village Ecotypes. Ames (Iowa): Iowa State University, January 2017. http://dx.doi.org/10.31274/ans_air-180814-365.
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Fleming, Damarius S., James E. Koltes, Eric R. Fritz-Waters, James M. Reecy, and Susan J. Lamont. SNP Discovery and Genomic Architecture of Highly Inbred Leghorn and Fayoumi Chicken Breeds Using Whole Genome Resequencing. Ames (Iowa): Iowa State University, January 2015. http://dx.doi.org/10.31274/ans_air-180814-1317.
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Amuzu-Aweh, Esinam Nancy, Boniface Babore Kayang, Amandus Pachificus Muhairwa, Huaijun Zhou, Rodrigo Gallardo, Tara Kelly, Susan J. Lamont, and Jack C. M. Dekkers. Estimating Genetic Parameters for Growth and Response to Infection with La Sota lentogenic Newcastle Disease Virus Strain in Local Chicken Breeds in Ghana and Tanzania. Ames (Iowa): Iowa State University, January 2017. http://dx.doi.org/10.31274/ans_air-180814-322.
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Heller, Dan, Karel Schat, and Ronnie Friedman. Marek's Disease Vaccination Breaks: Interaction of Genetic Strains of Chickens, Chicken Anemia Agent and Stressors. United States Department of Agriculture, June 1993. http://dx.doi.org/10.32747/1993.7603808.bard.
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Schat, Karel Antoni, Irit Davidson, and Dan Heller. Chicken infectious anemia virus: immunosuppression, transmission and impact on other diseases. United States Department of Agriculture, 2008. http://dx.doi.org/10.32747/2008.7695591.bard.
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1. Original Objectives. The original broad objectives of the grant were to determine A) the impact of CAV on the generation of cytotoxic T lymphocytes (CTL) to reticuloendotheliosis virus (REV) (CU), B). the interactions between chicken anemia virus (CAV) and Marek’s disease virus (MDV) with an emphasis on horizontal spread of CAV through feathers (KVI), and C) the impact of CAV infection on Salmonella typhimurium (STM) (HUJI). During the third year and the one year no cost extension the CU group included some work on the development of an antigen-antibody complex vaccine for CAV, which was partially funded by the US Poultry and Egg Association. 2. Background to the topic. CAV is a major pathogen causing clinical disease if maternal antibody-free chickens are infected vertically or horizontally between 1 and 14 days of age. Infection after 3 weeks of age when maternal antibodies are not longer present can cause severe subclinical immunosuppression affecting CTL and cytokine expression. The subclinical immunosuppression can aggravate many diseases including Marek’s disease (MD) and several bacterial infections. 3. Major conclusions and achievements. The overall project contributed in the following ways to the knowledge about CAV infection in poultry. As expected CAV infections occur frequently in Israel causing problems to the industry. To control subclinical infections vaccination may be needed and our work indicates that the development of an antigen-antibody complex vaccine is feasible. It was previously known that CAV can spread vertically and horizontally, but the exact routes of the latter had not been confirmed. Our results clearly show that CAV can be shed into the environment through feathers. A potential interaction between CAV and MD virus (MDV) in the feathers was noted which may interfere with MDV replication. It was also learned that inoculation of 7-day-old embryos causes growth retardation and lesions. The potential of CAV to cause immunosuppression was further examined using CTL responses to REV. CTL were obtained from chickens between 36 and 44 days of age with REV and CAV given at different time points. In contrast to our earlier studies, in these experiments we were unable to detect a direct impact of CAV on REV-specific CTL, perhaps because the CTL were obtained from older birds. Inoculation of CAV at one day of age decreased the IgG antibody responses to inactivated STM administered at 10 days of age. 4. Scientific and Agricultural Implications The impact of the research was especially important for the poultry industry in Israel. The producers have been educated on the importance of the disease through the many presentations. It is now well known to the stakeholders that CAV can aggravate other diseases, decrease productivity and profitability. As a consequence they monitor the antibody status of the breeders so that the maternal antibody status of the broilers is known. Also vaccination of breeder flock that remain antibody negative may become feasible further reducing the negative impact of CAV infection. Vaccination may become more important because improved biosecurity of the breeder flocks to prevent avian influenza and Salmonella may delay the onset of seroconversion for CAV by natural exposure resulting in CAV susceptible broilers lacking maternal antibodies. Scientifically, the research added important information on the horizontal spread of CAV through feathers, the interactions with Salmonella typhimurium and the demonstration that antigen-antibody complex vaccines may provide protective immunity.
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Malkinson, Mertyn, Irit Davidson, Moshe Kotler, and Richard L. Witter. Epidemiology of Avian Leukosis Virus-subtype J Infection in Broiler Breeder Flocks of Poultry and its Eradication from Pedigree Breeding Stock. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586459.bard.
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Objectives 1. Establish diagnostic procedures to identify tolerant carrier birds based on a) Isolation of ALV-J from blood, b) Detection of group-specific antigen in cloacal swabs and egg albumen. Application of these procedures to broiler breeder flocks with the purpose of removing virus positive birds from the breeding program. 2. Survey the AL V-J infection status of foundation lines to estimate the feasibility of the eradication program 3. Investigate virus transmission through the embryonated egg (vertical) and between chicks in the early post-hatch period (horizontal). Establish a model for limiting horizontal spread by analyzing parameters operative in the hatchery and brooder house. 4. Compare the pathogenicity of AL V-J isolates for broiler chickens. 5. Determine whether AL V-J poses a human health hazard by examining its replication in mammalian and human cells. Revisions. The: eradication objective had to be terminated in the second year following the closing down of the Poultry Breeders Union (PBU) in Israel. This meant that their foundation flocks ceased to be available for selection. Instead, the following topics were investigated: a) Comparison of commercial breeding flocks with and without myeloid leukosis (matched controls) for viremia and serum antibody levels. b) Pathogenicity of Israeli isolates for turkey poults. c) Improvement of a diagnostic ELISA kit for measuring ALV-J antibodies Background. ALV-J, a novel subgroup of the avian leukosis virus family, was first isolated in 1988 from broiler breeders presenting myeloid leukosis (ML). The extent of its spread among commercial breeding flocks was not appreciated until the disease appeared in the USA in 1994 when it affected several major breeding companies almost simultaneously. In Israel, ML was diagnosed in 1996 and was traced to grandparent flocks imported in 1994-5, and by 1997-8, ML was present in one third of the commercial breeding flocks It was then realized that ALV-J transmission was following a similar pattern to that of other exogenous ALVs but because of its unusual genetic composition, the virus was able to establish an extended tolerant state in infected birds. Although losses from ML in affected flocks were somewhat higher than normal, both immunosuppression and depressed growth rates were encountered in affected broiler flocks and affected their profitability. Conclusions. As a result of the contraction in the number of international primary broiler breeders and exchange of male and female lines among them, ALV-J contamination of broiler breeder flocks affected the broiler industry worldwide within a short time span. The Israeli national breeding company (PBU) played out this scenario and presented us with an opportunity to apply existing information to contain the virus. This BARD project, based on the Israeli experience and with the aid of the ADOL collaborative effort, has managed to offer solutions for identifying and eliminating infected birds based on exhaustive virological and serological tests. The analysis of factors that determine the efficiency of horizontal transmission of virus in the hatchery resulted in the workable solution of raising young chicks in small groups through the brooder period. These results were made available to primary breeders as a strategy for reducing viral transmission. Based on phylogenetic analysis of selected Israeli ALV-J isolates, these could be divided into two groups that reflected the countries of origin of the grandparent stock. Implications. The availability of a simple and reliable means of screening day old chicks for vertical transmission is highly desirable in countries that rely on imported breeding stock for their broiler industry. The possibility that AL V-J may be transmitted to human consumers of broiler meat was discounted experimentally.
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Lamont, Susan J., E. Dan Heller, and Avigdor Cahaner. Prediction of Immunocompetence and Resistance to Disease by Using Molecular Markers of the Major Histocompatibility Complex. United States Department of Agriculture, September 1994. http://dx.doi.org/10.32747/1994.7568780.bard.
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This project utilized two live-animal populations in an integrated research program to identify molecular markers for immune response and disease resistance. The populations each had their foundation from meat-type commercial breeder chicken lines of their respective countries. Investigations effectively used unique availability of resources in each country to study commercial-type environments in Israel and line-crosses with diverse inbred lines in the US. Two bacterial systems were investigated to cover both respiratory and gastrointestinal, and primary and secondary, infections. Individual experimental groups of animals were evaluated for combinations of vaccine antibody levels, response to pathogen challenge, growth parameters, genetic background and molecular markers. The positive association of antibody level with resistance to disease was confirmed. Effectiveness of genetic selection for vaccine antibody response level was demonstrated. Molecular markers, both inside and outside the MHC region, were associated with antibody response and resistance to disease. Markers were shown to have a generalized effect, by association with multiple traits of immune response and disease resistance. The impact of genetic background on marker effect was shown to be important. The overall results demonstrate the effectiveness of selection on vaccine antibody response and the potential of molecular marker-assisted selection to improve efficiency of production of meat-type chickens by reducing genetic susceptibility to disease.
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Uni, Zehava, and Peter Ferket. Enhancement of development of broilers and poults by in ovo feeding. United States Department of Agriculture, May 2006. http://dx.doi.org/10.32747/2006.7695878.bard.
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The specific objectives of this research were the study of the physical and nutritional properties of the In Ovo Feeding (IOF) solution (i.e. theosmostic properties and the carbohydrate: protein ratio composition). Then, using the optimal solution for determining its effect on hatchability, early nutritional status and intestinal development of broilers and turkey during the last quarter of incubation through to 7 days post-hatch (i.e. pre-post hatch period) by using molecular, biochemical and histological tools. The objective for the last research phase was the determination of the effect of in ovo feeding on growth performance and economically valuable production traits of broiler and turkey flocks reared under practical commercial conditions. The few days before- and- after hatch is a critical period for the development and survival of commercial broilers and turkeys. During this period chicks make the metabolic and physiological transition from egg nutriture (i.e. yolk) to exogenous feed. Late-term embryos and hatchlings may suffer a low glycogen status, especially when oxygen availability to the embryo is limited by low egg conductance or poor incubator ventilation. Much of the glycogen reserve in the late-term chicken embryo is utilized for hatching. Subsequently, the chick must rebuild that glycogen reserve by gluconeogenesis from body protein (mostly from the breast muscle) to support post-hatch thermoregulation and survival until the chicks are able to consume and utilize dietary nutrients. Immediately post-hatch, the chick draws from its limited body reserves and undergoes rapid physical and functional development of the gastrointestinal tract (GIT) in order to digest feed and assimilate nutrients. Because the intestine is the nutrient primary supply organ, the sooner it achieves this functional capacity, the sooner the young bird can utilize dietary nutrients and efficiently grow at its genetic potential and resist infectious and metabolic disease. Feeding the embryo when they consume the amniotic fluid (IOF idea and method) showed accelerated enteric development and elevated capacity to digest nutrients. By injecting a feeding solution into the embryonic amnion, the embryo naturally consume supplemental nutrients orally before hatching. This stimulates intestinal development to start earlier as was exhibited by elevated gene expression of several functional genes (brush border enzymes an transporters , elvated surface area, elevated mucin production . Moreover, supplying supplemental nutrients at a critical developmental stage by this in ovo feeding technology improves the hatchling’s nutritional status. In comparison to controls, administration of 1 ml of in ovo feeding solution, containing dextrin, maltose, sucrose and amino acids, into the amnion of the broiler embryo increased dramatically total liver glycogen in broilers and in turkeys in the pre-hatch period. In addition, an elevated relative breast muscle size (% of broiler BW) was observed in IOF chicks to be 6.5% greater at hatch and 7 days post-hatch in comparison to controls. Experiment have shown that IOF broilers and turkeys increased hatchling weights by 3% to 7% (P<0.05) over non injected controls. These responses depend upon the strain, the breeder hen age and in ovo feed composition. The weight advantage observed during the first week after hatch was found to be sustained at least through 35 days of age. Currently, research is done in order to adopt the knowledge for commercial practice.
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Lamont, Susan J., Michael G. Kaiser, Max F. Rothschild, Michael E. Persia, Chris Ashwell, and Carl Schmidt. Breed Differences in Physiologic Response to Embryonic Thermal Conditioning and Post-hatch Heat Stress in Chickens. Ames (Iowa): Iowa State University, January 2015. http://dx.doi.org/10.31274/ans_air-180814-1316.
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Malkinson, Mertyn, Richard Witter, and Irit Davidson. Reduction of Reticuloendotheliosis in Foundation Breeding Flocks of Chickens: A Combined Immunological and Molecular Biological Approach. United States Department of Agriculture, February 1996. http://dx.doi.org/10.32747/1996.7613026.bard.
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Reticuloendotheliosis virus (REV) is an avian retrovirus that can cause immunosuppression, growth retardation and tumors. An attempt to define the extent of the economic damage to the poultry industry that it causes is discussed in this report. In addition to losses experienced by commercial laying flocks, reduced rates of hatchability and embryo developmental disorders were demonstrable due to vertical transmission of the virus. I. Eradication of REV In this project a comprehensive national program was applied for the eradication of REV from Israeli breeding stocks by the elimination of antibody-positive birds from the breeding program. The prevention of REV-infected breeders entering Israel was also implemented by serological examination of imported day-old chickens and turkeys for maternal antibody. At the same time commercial breeding flocks in Israel were surveyed routinely to measure the extent of environmental exposure to REV throughout Israel. II. Economic factors associated with vertical transmission on breeders and progeny It was observed that on some poultry farms exposure of breeding flocks to viral infection, if it occurs when the birds are immunocompetent, leads only to a seroconvertion event. In these flocks no differences were demonstrated between the performances of seronegative and seropositive birds. When the F1 generation was selected according to seronegativity of the parents, all the progeny were seronegative, indicating that tolerantly infected birds did not form a significant proportion of the parent flock. In sharp contrast, breeding flocks that became exposed to the virus about the point of lay or during the laying period, shed virus vertically for a brief period of time through the egg. Our epizootiological observations lead us to conclude that the progeny (laying pullets) becomes tolerantly infected and are immunosuppressed as they increase in age. Increased mortality and susceptibility to intercurrent diseases were recorded.