دکتر حسن مهربانی یگانه

The objective of this research was estimation of genetic correlations between production and linear type traits in Holstein cows, through a meta-analysis study. Using a systematic search of the literature, we found 27 papers in which the estimation of genetic correlations among production and type traits were reported. On the whole, the published data had been recorded from 1407598, 1252515 and 1159124 animals, respectively corresponded to milk yield, fat and protein content. Analyses were performed by using the metafor-package of R environment. The obtained results showed that there are low to moderate genetic correlations among production and type traits. Milk yield showed higher genetic correlation with angularity 0.36, body condition score -0.31, udder depth -0.30, and rear udder width 0.26. Fat content also was genetically correlated with angularity 0.39 and body condition score -0.25. In addition, protein content had high genetic correlation with angularity 0.46, rear udder width 0.39, udder depth -0.29, and rump angle 0.28. According to the meta-analysis, angularity was distinguished as a main type trait that displayed the highest genetic correlation with production traits. Test of heterogeneity ( statistics) indicated that there was significant heterogeneity (variance among studies) at the highest level (more than 99%). All type traits which had high genetic correlation with production traits would be recommended for being used as indicator traits of production by virtue of the size of their correlations with production traits. Results of this study can be used for estimating type traits economic values in Holstein cow’s selection indices.

Linear type traits are recorded for some reasons in dairy cattle. Cows might reach to a high length of productive life and milk yield based on their ideal scores of type traits. In the dairy industry, type traits have indirect economic values due to genetic correlation with production, reproduction, clinical mastitis and length of productive life. The main object of our study was to identify type traits that have high enough genetic correlation with length of productive life, clinical mastitis and somatic cell score. Therefore, we conducted a meta-analysis as a statistical tool, on studies investigating the correlation between length of productive life, incidence of clinical mastitis, and somatic cell score with type traits in Holstein dairy cows.

A comprehensive search of the literature was conducted using the key words “genetic correlation”, “type traits”, “length of productive life”, “clinical mastitis”, “somatic cell score” , “Holstein cow” in Google Scholar search engine. Out of the 103 potentially relevant papers found, 75 studies were excluded from the analysis, because these studies did not contain appropriate data. Finally, from the search results, we prepared three real data sets in relation to genetic correlation of linear type traits with length of productive life (6 studies), clinical mastitis (8 studies), and somatic cell score (17 studies) in Holstein cows. These studies involved the total of 263065, 4716267 and 922090 animals, corresponded to length of productive life, clinical mastitis and somatic cell score, respectively. Analyses were performed using “metafor” procedure in R software package. Due to the differences in estimation methods and sample sizes in different studies, a random model was used to perform the meta-analysis and to estimate key statistics such as effect size, 95% confidence interval and measure of heterogeneity ).

The obtained results from meta-analysis showed that the type traits with higher genetic correlations with length of productive life were central ligament 0.19 and udder depth 0.14. Furthermore, somatic cell score was more genetically correlated with body condition score (-0.31) and udder depth (-0.25). The largest genetic correlation of clinical mastitis estimated was with udder depth (-0.28) and teat length (-0.23). Test of heterogeneity (statistics) indicated that there was significant heterogeneity (variance among studies) at the highest level (more than 99%). Results of this study might indirectly be applicable for estimation of type traits’ economic values of Holstein cow’s selection indices.

Meta-analysis of genetic correlation between length of productive life, somatic cell score and clinical mastitis with linear type traits clarified that central ligament, udder depth, body condition score and  chest width could be used as indicator traits in Holstein cows breeding programs. Results suggest that central ligament and udder depth as main mammary system traits potentially might be taking into account to constract indices for selection in dairy breeding programs. Cows can produce higher amount of milk and spend higher productive period when they have achieved to ideal scores of type traits.

 Selection in animal populations to increase the frequency of ideal alleles causes of remaining some signs in the animal genome, which are usually associated with important traits. Today, with developments in next-generation sequencing and easier access to animal genomic information, some models have been proposed to identify selective signatures based on allelic frequency and haplotype blocks. This research aimed to identify the selective signatures in two horse breeds of Caspian and Kurdish using a k70 SNP chip.

 In this research blood samples from 35 Caspian and 31 Kurdish horses were collected. After DNA extraction and sequencing (by Illumina company), Quality control of the data was performed for minimum allele frequency (PMAF<0.05), genotyping rate (PGENO < 0.5), and deviation from Hardy-Weinberg equilibrium (PH-W<1 ͯ 10-6). Then the theta (θ) test and ensemble site were used for identifying selective signatures and the positions of snaps respectively, and finally, the genes related to these positions were identified.

 After quality control of data and integration of genomic data of two populations based on R package protocols, 61 horses with 52,650 SNPs remained for the rest analysis. Finally, Fst statistical test based on unbiased estimator theta method 31 differentiating markers of the two studied horse breed were identified

The results showed that Caspian and Kurdish horse breeds belong to two separate groups. The Kurdish horse breed has more diversity and variety than the Caspian. The most important genes associated with significant SNPs were INPP5F, HPSE2, R3HCC1, DOCK3, ITGB6, GM6B, PHEX, WDR13, LRCH2, GRIA3 and THOC2. Most of the identified genes were associated with intercellular exchanges, muscle contractions, immunity, membrane support, DNA stability, and the nervous system.

In this study, genomic data of 590 cattle were used including native breeds of Sarabi, Kermani, Kurdi, Talashi, Sistani, Najdi, Mazandarani and Pars, crossbred from northwest of Iran, Holstein populations from Iran, France and Ireland. Quality control and data filtration were performed using Plink 1.9 software. After this quality control, individuals and SNPs with call rate below 0.95%, SNP makers with minor allele frequency (MAF) > 0.01%, divergence from Hardy-Weinberg Equilibrium were excluded. This procedure yielded 509 individuals with 13512 SNP marker. Then filtered data were used to genetic diversity and clustering analysis. Identification of genetic groups were performed using PCA analysis data by GenABEL software. PCA and ADMIXTURE analysis showed that studied populations are in 4 separate categories including purebred Sarabi population in the first group, crossbred from northwest of Iran in the second group, purebred Holstein populations in the third group and native breeds of Iran were in the fourth group. Further details of demographic differentiation were identified by Weir and Cockerham's fixation index. The range of differentiation in the present study varied from 0.180 between Sistani and Kurdish breeds to 0.007 to 0.004 between the Iran Holstein breed and Ireland with France Holstein breeds. The results showed that the highest difference between indigenous and Holstein breeds related to Sistani breed that had the highest difference with different Holstein breeds (0.128 to 0.138). With slight differences from other Iranian indigenous breeds, the Kurdish and Mazandaran breeds had the smallest genetic differences with the studied Holstein populations.

Selection to increase the frequency of new mutations useful only in some subpopulations leaves markers at the genome level. Most of these regions are related to genes and QTLs controlling significant economic traits.

In order to detection of genetic differences between Iranian northwestern crossbred and Holstein cattle breed, respectively number of 100 and 60 sample from Iranian north-west hybrid and Holstein populations were used. After ensuring the distinct structure of the studied populations, FST, XP_EHH and Rsb statistics were used to identify the selection signatures and 21, 16 and 24 regions exceeding the threshold were identified as signatures of selection respectively. These selected genomic regions were surveyed and 104 and 135 genes were extracted from the corresponding areas in ARS-UCD1.2 Bos Taurus Genome Assembly for FST and LD based methods, respectively.

Some of detected genes in regions under selection were involved in metabolic pathways related to taste, smell, fat metabolic pathways, resistance to disease and reproduction performance. Some of detected genes were involved with milk production by involving in WNT (Wingless-type) signaling pathway. The selected genomic regions were further examined for further analysis and finding of gene networks. These analyzes were performed by online software related to the genomic database (DAVID). Only one significant network was identified (p<4.5×10-9). This gene network communicates with taste receptors and specially detection of bitter tastes.

In addition to better understanding about natural and artificial selection effects on the Holstein breed and Iraniannorth-west indigenous hybrid, the selected regions can helpus to detecte QTLs and regions associated with important economic traits. In any case, it will be necessary to carry out more association and functional studies to demonstrate the implication of these genes.

The aim of the present study was to investigate the effect of dietary supplementation of organic selenium (oSe) on blood parameters of male broiler breeder under dexamethasone (Dexa) challange. Fifty broiler breeder roosters (Ross 308) at the age of 64 weeks were randomly allotted to five groups (10 roosters/group) and fed a standard diet supplemented with different levels of oSe during 10 successive weeks of the experimental period. To induce stress, dexamethasone (2 mg/kg body weight) was injected during weeks of 4 to 6 of the experiment, in one-day-interval manner. Experimental treatments including diet without oSe supplementation and Dexa treatments (negative control; NC), or treated with Dexa and different levels of oSe including 0 (positive control; PC), 0.15 (Se15+Dexa), 0.30 (Se30+Dexa) or 0.45 (Se45+Dexa) mg/kg of diet. During the experimental period, concentration of testosterone, corticosterone, malondialdehyde (MDA), total antioxidant capacity (TAC), hepatic enzymes activity (ALT and AST), uric acid, total protein, albumin, plasma lipid and glucose parameters, were evaluated every two weeks. Liver enzymes and glutathione peroxidase (GPX) activity, TAC, concentration of uric acid, total protein, albumin and glucose were not affected by the treatments. Dexamethasone injection increased plasma concentrations of total cholesterol, HDL, LDL and MDA in the PC group compared to the NC group (P<0.05). However, oSe ameliorated these negative impacts in dexamethasone-stressed roosters (P<0.05). Generally, the results of this study indicate that dietary inclusion of oSe mitigate the negative effects of Dexa on some blood parameters in roosters under dexamethasone challange.

The present study was conducted to investigate the effect of dietary Curcumin supplementation on histological parameters of testis in aged Ross 308 broiler breeder roosters. A total of twelve 48-week old broiler breeder roosters in a completely randomized design were randomly assigned to four treatments and three replicates during a 13 weeks of experimental period. Treatments included no dietary Curcumin supplementation (control group), and daily supplementation of 10, 20, and 30 mg Curcumin/birds as mixed in the basal diet. At the end of the experimental period, all of the roosters were slaughtered, and testis tissue samples were collected. Testicular weight was higher in the roosters that daily received 30 mg Curcumin compared with the control group (P<0.05). Dietary supplementation of 20 and 30 mg Curcumin/day increased the diameter of seminiferous tubule compared to the control group (P<0.05). Seminiferous epithelium thickness was dose-dependently increased in Curcumin-supplemented birds compared to the control group (P<0.05). The number of spermatogonia cells was increased in all treatment groups compared to the control group (P<0.05). The number of Leydig cells was also increased in roosters received 20 and 20 mg Curcumin/day compared to the control birds (P<0.05). However, treatments did not affect the number of testis blood vessels (P>0.05). According to the results of the present study, dietary supplementation of 30 mg Curcumin/day/bird improves testis histological parameters in aged broiler breeder roosters.

The aim of this research was to utilize a simple, rapid, cheap and safe method for sex determination of newly born canaries through feather to help accurately breeding this bird. The external morphology of males and females of many birds such as canary are fairly similar to each other, Therefore, determining their sexes is very difficult. The different length of CHD (chromo-helicase-DNA-binding) gene in Z and W chromosomes can recignized by using molecular technique based and PCR method, for the sex determination of young birds. In this study, blood and feathers samples of 140 canaries from 10 different breeds were used and their DNA were extracted. It should be mentioned that for PCR, at first 5 primers designed and finally 1 specific primer were confirmed and used. The results showed that the amplification of a fragment with the length of 252 bp for males (ZZ) and two fragments with the lengths of 252 and 309 bp for female (ZW). The bands had a length difference of 57 bp. The DNA sequencing of these two fragments was done for the first time, the sequence of these two fragments of the CHD gene in canary species was submitted and accepted in the NCBI site under the names of CHDZ-1 and CHDW-1 with the accession numbers of MG679825.1 and MG679826.1.

The Arab horses are famous for endurance riding, jumping and beauty. Kurdish horses are native to hilly regions of west of Iran and they are suitable for Polo tournament. Kurdish horses are shorter and heavier than Arabian horses. In this study, we use the linkage disequilibrium-based method, XP-EHH statistic, for Identification of regions that have undergone selection in the genome of Arabian and Kurdish horses. For this purpose, genomic DNA from blood and hair samples from 38 Arabian and 58 Kurdish horses were extracted. All DNA samples genotyped by the Axiom MNEC670 array. After data pruning, XP-EHH statistic was calculated. We identified 51 genomic regions (85 genes) in Iranian Arab horses and 7 genomic regions (13 genes) in Kurdish horses showing signatures of selection. We found positively selected genomic regions in the Iranian Arab horses associated with immune system related pathways, milk protein formation, muscle growth and development, vision, nervous system and body size whereas in the Kurdish horses associated with G protein–coupled receptors, growth and maturation of muscle fibers, cellular oxygen homeostasis and skin and hair pigmentation.

Molecular genetics selection on individual genes is a promising method to genetically improve economically important traits in livestock. Growth hormone secretagogue receptor (GHSR) gene secreted by the stomach that has two important functions: the stimulation of the growth hormone production and the stimulation of feed intake. In this study, the association between gherlin receptor gene polymorphism (GHSR) with blood parameters and carcass traits in Zell and Shal sheep breeds were studied using PCR-SSCP and DNA sequencing.

Genomic DNA was extracted from 51 adipose tissue samples using phenols chloroform method. The exon 2 (452 bp) of GHSR gene was amplified with designed specific primers. The single stranded conformation polymorphism (SSCP) patterns of PCR product were studied using 12% Acrilamid gel and silver staining method. In the present study, after revealing genotype of animals for the GHSR locus, this data along with data related to studied traits were analyzed by the least-squares method as applied in the General Linear Model (GLM) procedure of SAS 9.2 program.
sequencing show a novel single nucleotide polymorphism in this gene on the nucleotide position 3278 converting T to C.

This SNP had a significant effect on red meat trait (P<0/05), carcass pH (P<0/002) and ash (P<0/06) in Zel and Shal breed in such a way that the CT genotype was more desirable than TT genotype in red meat and carcass pH traits. The value of least square means of the CC genotype was higher than CT genotype in ash trait. Breed had significant effect on hot carcass weight (P <0/0001), carcass yield (P <0/04), pH (P <0/01), shear force (P <0/001), water holding capacity of the first day (P <0/05), LDL (P <0/02), b * (P <0/0001), l * (P <0/007). The results showed that sex had a significant effect on hot carcass weight (P <0/0008), PH (P <0/01), water holding capacity on the first day (P <0/05) and LDL (P <0/02) traits. The effect of Males was higher effect than females on hot body weight and water holding capacity on the first day. The females had higher effect in LDL, b * and l * traits. In this study there was no significant association between SNP and saturated and unsaturated fatty acids traits.

The results showed that the gherlin receptor gene (GHSR) could be regarded as a possible candidate gene for selection in Zell and Shal sheep breeds

At this study, with using from univariate and multivariate Econometrics Models of time series techniques, the annual prices from 2015 to 2020 for Iran and from 2014 to 2020 for world was predicted. The Iran data related to the chicken price, corn price, soybean meal price and chicken production rate from 1990 to 2014 were provided from Ministry of Agriculture Iran, State Livestock Affairs Logistics (S.L.A.L) Inc. and Central Bank of the Islamic Republic of Iran and the world data are provided from FAO STAT for the year 1961-2013. The most appropriate model for fitness and prediction of chicken meat in Iran is the autoregressive moving average model (ARMAX (3,5)), with the in-sample and out of sample of predicting error are 2.12 and 4.7 percent and in world, autoregressive moving average model (ARMA (1,13)) with the in-sample and out of sample of predicting error are 4.34 and 3.91 percent, according to mean absolute percent error criterion. Also the results of vector error correction models (VECM) estimation have shown one unit increasing in the ratio of the price of corn to soy and the amount of meat production in Iran, can increase 7.59 and 3.29 percent in Iran chicken meat and one unit increasing in world price of corn and the amount of world production of chicken meat can cause increase equal 0.31, 0.46 and 0.64 percent in chicken meat world price.

In this research genetic variation using 6 microsatellite loci (HMS07, HMS03, HMS02, HMS06, ASB02, ASB23) was studied in Iranian Kurdish horse population .Whole blood samples were randomly collected from 52 horses in Kurdistan, Kermanshah, Elam, Western Azerbaijan, Esfahan, Kerman and Hamadan regions. DNA was extracted from blood samples. Polymerase chain reaction (PCR) was used for amplification of 6 microsatellite loci using pairs of standard specific primers. Then, the PCR products assessed with 8% silver-staining acrylamide gel and electrophoresed. All microsatellites loci were polymorphic. The number of alleles observed and expected hetrozygosities were calculated with Shannon Index. The largest and smallest number of alleles were observed in HMS07 locus (10 alleles) and HMS02 (4 alleles) respectively. Our results confirmed the high efficiency of microsatellite markers for assessing population structure in Iranian native horses.

The Arab horse breed is one of the most ancient horse breeds. Arabian horses are famous for endurance riding and flat racing. Moreover, this breed has contributed to the formation of some of the most important horse breeds in the world. Kurdish horses are found in rough terrain and hilly regions and they are suitable for riding in hilly areas and Polo tournament. To investigate the population structure and to find the signatures of selection in the genome of Arabian and Kurdish horses, blood and hair samples from 38 Arabian and 58 Kurdish horses were taken and genotyped using the 670K Axiom Equine Genotyping Array. Principal component analysis (PCA) was carried out on the genotypic data and Fst statistic for each SNP was calculated. Fst values were smoothed over each chromosome. PCA showed that the Arabian horse population is more genetically diverse than the Kurdish horses. We identified six genomic regions showing signatures of selection. The strongest signal of selection was found in ECA8. Annotation of the regions of the genome that showed selection signatures revealed candidate genese.g. CaMKK2, MLXIP and ATP2A2 that may involve in endurance riding and racing. These genes for further studies are proposed.

In order to evaluate the effects of genomic and traditional selection methods onlong term response to selection, genetic variance and inbreeding, a base population of 100 animals was randomly mated for 50 generations. The simulated genome size for each animal was 10 Morgan that was equally divided between 10 chromosomes. On each chromosome, 1000 SNP markers were evenly located. Two traits with the heritability of 0.5 and 0.1 were simulated for each animal and 200 QTL were randomly distributed over the genome for each trait. BLUP method was used for prediction of traditional breeding value as well as estimation of SNP effects. Genomic breeding values of the animals for each trait were sum of SNP effects for all loci. After generation 51, animals were selected based on traditional breeding values or genomic breeding values for 15 generations. The results of this study showed that for both traits the genomic selection method increased response to selection, butdecreased genetic variance relative to the traditional selection. Greater response to selection and reduction in genetic variance was for trait with higher heritability. A twofold increase in the inbreeding coefficient was observed for traditional selection relative to genomic selection after 15 generations of selection.

The aim of this study was to investigate the association of bovine leukocyte antigen-DRB3 alleles with peripheral blood mononuclear cell (PBMC) proliferation in response to Staphylococcus aureus. The animals included in this study (n=347) were approximately of same age and comprised of F2 Holstein-Friesian ´ Charolais (n = 155), Holstein-Friesian backcross (F0 Holstein-Friesian dams crossed with unrelated F1 sires, n = 60), Charolais backcross (F1 dams crossed with F0 Charolais sire, n=46) and pure Holstein-Friesian (n = 86). A sequence-based typing method was used in order to determine the genotype of the animals at BoLA-DRB3 locus and a linear mixed model was used to evaluate the association of bovine leukocyte antigen-DRB3 alleles with peripheral blood mononuclear cell (PBMC) proliferation. Beside the BoLA-DRB3 alleles, fixed effects of genetic group and gender and random effect of sires were included into the statistical model. In this research, 27 alleles were found for BoLA-DRB3 gene. The results showed that alleles BoLA-DRB3*0101 and BoLA-DRB3*0902 significantly affected on the stimulation index of S. aureus–induced peripheral blood mononuclear cell proliferation (P

Selective signatures in whole genome can help us to understand the mechanisms of selection and to identify the genomic regions that have been under natural or artificial selection during long years. The objective of this study was to identify the genomic regions that have been under artificial and natural selection in Baluchi and Zel sheep breeds. 143 sheep from Baluchi (N=96) and Zel breeds (N=47) have been genotyped using the Illumina ovine SNP50 BeadChip. Unbiased method of Weir and Cockerham’s FST (Theta) was used to detect the selection signatures in the R package. The results revealed seventeen genomic regions on 3, 4, 5, 7, 10, 11, 12, 13, 15, 18 and X chromosomes. Bioinformatics analysis demonstrated that some of these genomic regions overlapped with reported genes included in the development of the skeletal system and tail, cytology cells, immune system, sugar and energy metabolism and reproduction traits such as RPS6KA3, HOXB9, ESPL1, AAAS, FNDC3A genes. The results of the present study and the identified genomic regions can play an important role in study of the effect of the selection on population differentiation in two Baluchi fat-tailed and Zel thin-tailed breeds and subsequently, would direct us to identify the genomic regions associated with traits differentiate these breeds.

To investigate accuracy of linkage disequilibrium (LD) in genomic simulation studies a base population was simulated in two statuses LD with values of zero and one in first generation. Effective population size، LD and variance of markers frequency were used for determination of simulation accuracy. The results showed a high correlation between actual and expected effective population sizes. Also observed and expected LD’s were nearly similar and the given trend was improved with increasing effective population size. In addition، the variances of the observed and expected free recombination markers frequency were adapted with each other. According to the evaluated criteria the base population was accurately simulated which it could be used to generate the reference population. Based on the results، we suggest that proposed criteria should be used to verify the simulation after creating of historical population in genomic simulated studies.

In recent years، the relationship between insertion and deletion (indel) polymorphisms in promoter region (23 bp) and intron 1 (12 bp) of PRNP gene (Prion protein coding gene) and their relationship to susceptibility of classical bovine spongiform encephalopathy (BSE) have been reported. Insertions of these two polymorphisms increase resistance to classical BSE، while the deletions of these two polymorphisms cause more susceptibility to classical BSE. In this study DNA of Iranian Holstein (n=50)، Golpayegani (n=62) and Sistani (n=60) was extracted by modified salting out method. The genes were amplified using specific primers and the genotypes were detected on polyacrylamide gels. Allelic data were tested by Exact Fisher test and genotypic and haplotypic data were tested using Chi-square test. The results showed that considering locus of three mentioned breeds were in Hardy-Weinberg equilibrium. The allelic، genotypic and haplotypic frequencies of the polymorphism of the mentioned genes were estimated in three Iranian cattle breeds and were compared among breeds under this study and the healthy and BSE-affected group of the German cattle (described by Sander et al.، 2004). According to the results of this study، if these two regions are the only regions affecting on the classical BSE، Golpayegani cattle have more resistant than healthy and BSE-affected of German cattle.

Potential relationships between amino acid motifs in the antigen binding groove of various alleles of the bovine major histocompatibility complex DR (BoLA-DR) molecule and Peripheral Blood Mononuclear Cell (PBMC) proliferation، in response to S. aureus and phytohemaglutinin، were investigated. The animals included in the study were approximately of the same age and comprised of pure Holstein-Friesian (n = 86)، F2 Holstein-Friesian Charolais (n = 155)، Holstein-Friesian backcross (F0 Holstein-Friesian dams crossed with unrelated F1 sires، n = 60)، Charolais backcross (F1 dams crossed with F0Charolais sire، n = 46). To determine BoLA-DRB3 alleles of the animals، a sequence-based typing method was employed. The amino acid sequence data encode various BoLA-DRB3 alleles، presented at the latest BoLA workshop، were utilized to determine the residues involved in the formation of the pockets in the antigen binding groove of various alleles of the BoLA-DR molecules. A linear mixed model was utilized to evaluate the potential relationships between amino acid motifs in the antigen-binding groove of various alleles of BoLA-DR molecule and PBMC proliferation.

The aim followed in this study was to use the multi and single trait analyses for a prediction of genomic and traditional breeding values and to make a comparison of the accuracies of these methods. A base population of 100 animals (50 males and 50 females) was randomly mated for 50 generations to create linkage disequilibrium among loci. The simulated genome size was 10 Morgan, equally divided among 10 chromosomes. On each chromosome, SNP markers were evenly located and QTLs randomly distributed over the genome. Single and multi-trait analyses were employed to BLUP estimate the SNP effects. Genomic breeding values of the animals, for each trait, amounted to the sum of SNP effects for all the loci. Results indicated that the accuracies of genomic breeding values were higher than those of traditional ones. Accuracy of breeding values increased as heritability, map density and the number of individuals, in training population, increased. High genetic correlation between the two traits led to the increased genomic and traditional breeding value accuracies.

The current study was conducted to investigate the effect of short-term selection in Japanese quail for its 4-week body and breast weights. Two selected lines, one for selection of body weight based upon in. breeding values (line 1) and another for breast weight based on between family selections (line 2) were randomly selected from a base population. In each generation, 39 sire and 78 dam-birds were taken as parents in each line and for the next generation. The number of selected replacements in line 2 was less due to decreasing population size. Data were collected over 2 consecutive hatches for 4 generations and selections responses determined for 3 generations. The levels of improvement of 4-week body weights in line 1 were recorded 14.4, 12.6 and 8.1 grams respectively for the 3 generations. Correlated response to breast weight in line 1 was 4.1, 3.6, and 3.2 grams in generations 2, 3, and 4, respectively. Directed selection from 4-week breast weight in line 2 led to improvements of: 4.0, 3.5 and 2.7 grams in generations 2, 3 and 4, respectively. Also, correlated responses for body weight in this line were recorded as: 14.5, 13.0 and 7.4 grams in generations 2, 3 and 4, respectively. There were significant differences in body weight and carcass traits between sexes and also in generations 2 and upward (P<0.01) but not for percentage components of carcass. Higher figures were obtained for femals than for males. Selection for 4-week body weights in line 1 and 4-week breast weights in line 2 improved Feed Conversion Ratios (FCR) for about 0.16 and 0.19 units over the selected periods, respectively. Genetic and phenotypic correlations between body and breast weights in line 1 were 0.90±0.12 and 0.73±0.06 and for line 2 they were: 0.85±0.06 and 0.82±0.02, respectively. Results obtained from this study do not support the in-between family selection as a tool to increase breast weight selection as based on body weight, due to its high genetic correlation with body weight (0.85-0.90), can be employed as a proper selection criterion for improving carcass traits, including breast weight.

Body Weight (BW) is a complex and important economic trait that may benefit from the implementation of Marker Assisted Selection (MAS). The objective followed in this study was to identify QTLs associated with BW at different ages as distinct traits based on an experimental half-sib cross of Japanese quails divergently selected for BW at 4 weeks of age. The body weights at hatch, and as well at one, two, three and four weeks of age were assessed in the F2 population. A total 220 F2 individuals were genotyped for 6 informative microsatellite markers located on chromosomes 1, 2 and 9. The interval mapping was conducted to identify putative QTLs. A QTL for BW at hatch while another at 1 wk of age were identified as significant on chromosome 2 (P<0.01) which may include 1.25% vs. 1.63% of the phenotypic variance, respectively. A QTL for BW at 3 wk of age can be susggested on chromosome 1. As for BW at 4 wk of age, one QTL was recognized as significant on chromosome 1 (P<0.01) while two suggested on chromosomes 2 and 9. A significant QTL explains 1.13% of the phenotypic variance. In conclusion, the results introduced some regions as harboring significant QTLs that affect BW traits. This study provided a potential for further work(s) on candidate gene(s), and Marker Assisted Selection for Body Weight traits.

The objective of this study was to investigate the effect of principal components (PC) of the regression coefficients (co)variance matrix on the lactation curve, and on the formation of selection index to modify the curve, based on these PC’s, and as well to estimate additive genetic and phenotypic variances and heritability of the constructed selection index. Lactation period of 301 d (5-305) was partitioned into 10 equal stages, such that the values of weighted coefficients (unrestricted selection index) were considered the same value as of the lactation stage. In contrast, the value of weighted coefficients (restricted selection index) which were calculated based on the genetic gain in each stage of lactation. The results showed that the first PC had an impact on milk production and the second PC was associated with persistency. The third PC increased (decreased) milk production in early and late (middle) lactation and the fourth PC decreased (increased) milk production in early (late) as well as middle of second (first) part of lactation curve. Because of more emphasis on persistency and decreasing genetic gain in early lactation in compared with, the value of weighted coefficients first (third) and second (fourth) PC were decreased (increased). Because of decreasing the variance of additive genetic in due to negative genetic covariance between the stages of lactation, the heritability of (0.08) decreased in comparison with (0.33) which lead to decline genetic gain.