جستجوی مقالات مرتبط با کلیدواژه « native fowls » در نشریات گروه « کشاورزی »

In the livestock industry, the accurate genetic evaluation of economic traits pre-request the existence of homogeneity in residual variance, however; in practice, such different production levels and data recording at different times and environments are unlikely to result in the homogeneity of residual variance. The aim of this study was to investigate the genetic variance of the residual variance for Egg Weight and Age at Sexual Maturity of Azerbaijan native chickens. Data set consisted 8283 Egg Weight (EW) records and 6608 Age at Sexual Maturity (ASM) records related to 9 generations from the indigenous chicken breeding centers in the west Azerbaijan. To investigate the genetic variation of the residual variance was using the BLUPF90 software. Heritability of EW and ASM in a single trait model was estimated to be 0.288 (s.e. =0.022) and 0.355 (s.e =0.127), respectively. The heritability of residual variance of these traits was estimated 0.00484 (s.e. =0.004) and 0.00005 (s.e. =0.002), respectively, indicating the slight possibility of their genetic progression by direct genetic selection. The values of genetic correlations between traits and their residual variance were estimated to be -0.154 and -0.076, respectively, suggesting that genetic selection for EW enhancement would improve the genetic value for their uniformity, but about ASM, the expected results will not be very favorable if the trait is reduced. In conclusion, for accurate estimation of breeding value and ranking based on production traits in poultry, special attention to variance heterogeneity and necessary corrections is inevitable.

The indigenous stocks play an important role in villager economy in developing countries, especially in Iran. Indigenous breeds could maintain higher level of performance under Incompatible environment compared to commercial strains. In classic breeding programs for poultry, selection of birds was based on phenotypic and pedigree information. The development of genomic selection prefers new strategies in animal breeding. Genomic selection has a major limitation for implementation. This method need genotyping of large numbers of markers for implementation and the costs of genotyping for these markers is high, especially for developing countries. To overcome this problem, before applying genomic selection, different scenarios have to be compared using computer simulation. The objective of this study was comparison of results in genomic selection and classic selection method in Iranian native fowls by using ZPLAN software (Täubert 2010). ZPLAN software is a very useful tool to optimize conventional and genomic breeding programs this software allows modeling of all relevant breeding structures, while taking all relevant biological, technological and economic parameters for complex breeding programs into account (Sitzenstock et al. 2013). This software then generates results such as the annual genetic gain for the breeding objective using a pure deterministic approach (Dekkers 2007). This program has been based on the discounted gene flow-method (Hazel 1943) and selection index theory (Hazel and Lush 1942). This software calculates genetic gain, discounted return, profit and costs within and over selection paths. The results of monetary in ZPLAN are standardized to an animal unit and are given per year (Sitzenstock et al. 2013).
Material and A reference scenario and a genomic scenario were simulated on 3460 birds in both sexes. Reference scenario was simulated based on phenotypic information and genomic scenario was simulated based on combination of phenotypic and genomic data with two reference populations of 500 and 1000 birds. Genomic data was based on the information of 4000 hens and variable numbers of cocks (800 to 4000). Studied traits included egg number, body weight at 8 weeks, mean of egg weight and age at sexual maturity. In this simulation, genetic and phenotypic parameters were used (Table 1). These parameters included: phenotypic standard deviation, heritability, genetic and phenotypic correlations and traits economic coefficients. Economic weights were based on the study of Kianimanesh et al. (2001) and the other parameters were extracted from the study of Yousefi 2012. The variable costs of rearing a cock or a hen were assumed to be 440000 Rial per animal (over a period of 20 weeks). During production, daily feeding costs resulted from a feed consumption of 0.11 kg per day at a price of 12000 Rial per kg. For each cock and hen, additional costs for the animal care (20000 Rial) were assumed. The costs of selection were assumed 40000 Rial per animal. The fixed costs were not considered in conventional scenario, because it was difficult to quantify them in breeding program. But these costs must reduce from profit. The interest rate was set to %7 for discounted costs and %2 for discounted returns (Sitzenstock et al. 2013).
The generation interval for both scenarios was 14.5 months. By adding genomic information to reference scenario, accuracy of estimations increased from 0.62 for chocks and 0.64 for hens in reference scenario to 0.77 for both sex in genomic scenario. Genetic development of traits increased with increase in the number of genotyped birds and the number of birds of reference population. Genetic development for traits egg number, body weight at 8 weeks, mean of egg weight and age at sexual maturity increased from 0.22, 2.57, 0.09 and -0.23 (Table 2) respectively in reference scenario to 0.30, 3.60, 0.11 and -0.27 respectively in genomic selection with 1000 reference population. The profit of breeding program was higher than reference scenario only in genomic scenario with reference population with 1000 birds (Figure 2). The discounted return per animal unit in the conventional scenario was 20102400 Rial per year. The variable costs for conventional scenario were 1057200 Rial per animal unit. This resulted in a profit of 19044800 Rial per animal unit. The accuracy of the genomic information and the size of the reference population have a large impact on the benefits from genomic selection. Dekkers 2007 showed that with increasing of marker information increased the benefits from genomic scenarios.
The use of genomic information caused increasing genetic development in all traits. Although in this study costs were not reduced, but genomic information increased the accuracy of selection of breeding program. This study showed that genomic selection can increase the genetic improvement rate of native chickens. However, the costs of genomic scenarios were higher than conventional scenario, but genomic information increased accuracy of selection and genetic gain of breeding goals traits. To overcome this problem, use of low density SNP chips is suggested.

Economically success incomerical and Native laying hen farms in some eaten is related to egg quality. So, egg quality is a one of the most important factor affecting hatchability and lead to increasing the egg demand. The current study was carried out in aim to estimate the genetic parameters for egg quality traits in Fars native fowls. To do this, 2000 pedigree recorded eggs were collected at Fars Native Breeding Center and external and internal egg quality traits were measured. Significance of environmental effects determined using GLM procedure by SAS software and those were considered in the mixed model analysis. Heritability, genetic and phenotypic correlations were estimated using ASREML software. The estimated heritability for egg weight and external egg quality traits including shell strength, shell weight, shell thickness were 0.21, 0.44, 0.23, 0.12. this parameter for internal egg quality traits including albumin height, albumin weight, Hough unit, yolk weight, yolk diameter were also estimated 0.17, 0.10, 0.17, 0.36, 0.13, respectively. Genetic and phenotypic correlations of egg weight with external and internal (except to yolk weight) egg quality traits were obtained positive. Both genetic and phenotypic correlations among external egg quality traits were found positive and ranged from 0.04 to 0.91. Yolk weight were negatively genetically correlated with yolk diameter and shell features (shell strength, shell thickness and shell weight). The genetic correlation of shell strength and traits such as albumin height, Hough unit, yolk weight and yolk diameter were low and in negative direction. The results showed that the selection for increasing egg weight lead to improvement of egg quality traits and decreased yolk weight in Fars native fowls.

Study of heritability, genetic and phenotypic correlations of internal egg quality traits.
The aim of this study was to evaluate of heritability, genetic and phenotypic correlations of internal egg quality traits in Azerbaijan native fowls.
Statistical models for all traits were fitted using GLM procedure of SAS software. Fixed effects including generation and incubation time were significant (P Results showed that direct heritability estimations for egg quality traits ranged from 0.12 for Haugh unit to 0.46 for yolk depth. There were high positive genetic and phenotypic correlations between albumen height and Haugh unit (0.96) as well as between egg weight and albumen weight (0.87).
Egg quality traits especially Haugh unit as a trait in the selection index, could be useful to improve internal egg quality in eggs of Azerbaijan native fowls.

Phosphoenolpyruvate carboxykinase (PEPCK) catalyzes the first step of the gluconeogenesis cycle. There are two isozymes forms of this enzyme, cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) and mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M) which present in mitochondria and cytoplasm Current research has been conducted to identify the allelic polymorphism in the PEPCK-M gene in breeder hens of native fowls and commercial broiler and layer chickens. Blood samples were collected randomly from 150 birds of three strains and DNA was extracted using modified salting out method. A fragment of 401 bp in length was amplified from exon 9 of PEPCK M gene. For genotyping of each sample the PCR products were digested by AccI restriction enzyme. The frequency of AccI- and AccI+ allele was estimated at 0.73 and 0.27 in native fowls population, 0.6 and 0.4 in broiler and 0.85 and 0.15 in layer lines, respectively. Two genotypes of AccI -/- and AccI -/+ were observed with the frequency of 0.46 and 0.54 in native fowls, 0.20 and 0.80 in broiler line and 0.70 and 0.30 in commercial layer line, respectively. The comparison of allelic frequency showed no statistical differences between native fowls population with broiler and layer lines, but this results indicated significantly differences between broiler and layer lines (P<0.05).The comparison of genotypic frequency showed that there were significant differences between three populations (P<0.05). No any AccI +/+genotype was detected in the genotyped samples. The difference in genotypic distribution may be as a consequence of different selection strategies used in these populations.

Avian influenza is a contagious viral disease affecting the respiratory, digestive and nervous system of birds belong to orthomyxovirus family. In the chicken Mx gene, type of amino acid at position 631 determines the antiviral activity against influenza and vesicular stomatitis virus. A single nucleotide polymorphism (SNP) at position 2032, responsible for the variation of amino acid at position 631 (Ser to Asn) of the Mx protein, has been demonstrated to be responsible for positive or negative antiviral activity of Mx proteins., The allele A and G at position 2032 corresponds to the positive and negative antiviral activity, respectively. In order to identify gene polymorphism at Mx locus, 250 blood samples randomly were collected from Sari, Shiraz, Mashhad native fowls breeding station, commercial broiler and layer flocks. DNA was extracted and a fragment with the length of 299 bp from the exon 13 of Mx locus was amplified by a specific primer pairs. PCR-RFLP method was used to identify of polymorphism in coding sequence of the Mx gene using Hpy8I restriction enzyme. The frequency of alleles were estimated A (0.692) and G (0.308) in Sari, A (0.577) and G (0.423) in Shiraz, A (0.604) and G (0.396) in Mashhad, A (0.46) and G (0.54) in commercial broiler and A (0.86) and G (0.14) in layer strain, repectively. According to the observed polymorphism at position 631 of Mx protein and its important role in susceptibility to influenza disease it may be possible to use this marker gene in breeding programs.

In order to detect polymorphism in TGF-b3 loci and effect of this gene on phenotypic and breeding values of body weight traits, blood samples were collected randomly from 120 hens of Fars native fowls. DNA was extracted using standard kit and a DNA fragment of 294 bp from TGF-b3 loci was amplified. After PCR, the amplified fragment digested using BsrI enzyme and revealed two alleles T and t with the frequency of 0.29 and 0.71, respectively. The frequencies of TT, Tt and tt genotypes were achieved 0.15, 0.275 and 0.575 respectively. Values for Shanon Index, Effective number of alleles, observed heterozygosity and expected heterozygosity for TGFb3 were 0.60, 1.69, 0.28 and 0.41 respectively. Results showed that this population has a good genetic diversity and must try to conserve it to use these valuable gene pools. T allele had significant effect on body weight gain at 1 day and 8 weeks (P 0.05). Our results demonstrated that this population has a good genetic diversity, thus these valuable gene pools should be conserved to be used in the future if needed. TGF-b3 gene can also consider as a candidate gene in breeding of this animal.