Body Weight Traits Research Articles

Insertion/deletion (InDel) variations in sheep PLAG1 gene locating in growth-related major QTL are associated with adult body weight and morphometric traits

Pleiomorphic adenoma gene 1 (PLAG1), locating in growth-related QTNs, was identified significantly affecting the body size of bovine, pig and mouse, while, the relationship between its genetic variation and ovine body size is still unknown. Here, two insertion/deletion (indel) loci of ovine PLAG1, including P1-del30bp and P5-del45bp, were investigated in 774 sheep from five breeds. The minor allele frequencies (MAF) of above indels were ranged from 0.093 to 0.276. The frequency of genotype DD in P1-del30bp site was significantly higher than others. As for P5-del45bp, the frequency of II genotype was higher than others. Moreover, the polymorphism information content (PIC) values of P1-del30bp and P5-del45bp was from 0.284 to 0.320 and 0.154 to 0.318 in these ovine breeds, respectively, which reflect relative high genetic diversity in sheep PLAG1. By Linkage disequilibrium (LD) test, the two indels were in strong linkage disequilibrium in D’ value, while the result of r2 test was opposite. The correlation analysis results showed that these indels of PLAG1 were significantly associated with 13 body morphometric traits especially body weight (P < 0.05). At P1-del30bp locus, it had higher significant correlation with chest width in LFTS ewe and cannon circumference index in Hu ewe (P < 0.01). At P5-del45bp locus, the cannon circumference in Lanzhou fat-tail sheep ewe, hip height of Tong ram and chest depth of Tan ram were higher significant (P < 0.01). These results demonstrated that the indel variants of sheep PLAG1 had associated with the body weight and morphometric traits of adult sheep, and these loci can be considered as molecular markers for sheep breeding.

Genetic and phenotypic parameters evaluation for body weight, conformation and production traits of indigenous Uttara using MMLSML

Genetic and phenotypic parameters evaluation for body weight, conformation and production traits of indigenous Uttara using MMLSML

Personality Traits and Obesity.

Objective: Previous studies investigating the association between body weight and personality traits have found mixed results. This paper uses a large data set and two different study designs (cross-sectional and longitudinal) to provide more consistent estimates of the effect of personality traits on obesity. Methods: The present study is based on data from the German Socio-Economic Panel (GSOEP) from the waves 2005 to 2013; GSOEP is a longitudinal survey of private households in Germany that has been carried out since 1984. Responses provided data about personality, measured using the BFI-S Questionnaire, data for self-rated body mass index BMI (to determine the obesity level), as well as information for potential confounders. Cross-sectional and longitudinal logistic regression models were used. Results: The cross-sectional study yielded statistically significant results for the association between the outcome variable and four personality factors neuroticism, extraversion, openness and agreeableness. After controlling for several potential confounders, the association between obesity and extraversion, openness as well as agreeableness remained; additionally, the personality factor consciousness reached statistical significance. In the longitudinal study, a statistically significant association was found only for two personality factors, namely extraversion and agreeableness. After adding the control variables, the FE-regression yielded an association only for agreeableness (negative). Gender differences were not significant. Discussion: The findings show that results of a cross-sectional study design differ from the outcome of the longitudinal study design. The latter stresses the association between excess weight and the personality factor agreeableness, contrasting with most outcomes of previous research.

Genetic parameters for tonic immobility, body weight, and morphological traits of the red-winged tinamou (Rhynchotus rufescens).

This study was carried out to estimate genetic parameters for morphology, body weight, and tonic immobility traits in the red-winged tinamou (Rhynchotus rufescens). Information on 690 birds was used and genetic parameters were estimated using Bayesian methods under a multi-trait animal model. The following traits were considered in this study: tarsal length (TL), bill length (BL), wing length (WL), head width (HW), bill width (BW), mature weight (MW), weight at 90days (W90), and tonic immobility (TI). The heritability showed estimates between 0.15 for wing length and 0.56 for bill length. Positive and negative genetic correlations were estimated, ranging from - 0.33 to 0.81. All the morphological, production, and behavioral traits studied will have moderate to high response to selection. The body weight at 90days is a better alternative for use in breeding programs and its selection would not lead to an increase in the time of tonic immobility. Both the selection for weight gain and for reduction of tonic immobility time would lead to an increase in the size of the legs of the red-winged tinamou, which could be advantageous for thermal control of these birds in tropical systems.

Evidence of nutrient by genotype interaction in meat quail strains through reaction norm models

Quails raised under different nutrition levels could lead to genetic variation affecting the genetic gain due to the genotype by environment (GxE) interaction. Thus, reaction norm models were carried out to evaluate the GxE interaction of two meat quails’ strains (LF1 and LF2) raised under different tryptophan:lysine ratios for body weight and carcass traits. A total of 590 and 587 meat quails for LF1 and LF2, respectively, were raised under five different tryptophan:lysine ratios (0.15, 0.20, 0.25, 0.30 and 0.35) in final growth phase diet. The tryptophan:lysine ratios exhibited an important influence on the genetic parameters of body weight and carcass traits. Heritability and additive genetic variance estimates increased as tryptophan: lysine ratios increased, except for body weight at 28 and 35 days in LF2 strain. Lower correlation estimates and re-ranking of estimated breeding values were observed for slaughter weight, breast weight and thigh + leg yield in LF2 strain and for carcass yield in LF1 strain. It indicated a striking effect of amino acid ratios in quail carcass traits. The genetic evaluation and selection for carcass trait in quail strains raised under different tryptophan:lysine ratios should be considered in quail breeding programs.

A novel diplotype in the GH gene associated with body weight traits around the first overwintering period in common carp (Cyprinus carpio L.) cultured in Northeast China

Common carp cultured in Northeast China need at least 3 or 4 years to become sexually mature. Consequently, in regard to local seed production enterprises, increasing selection accuracy with excellent growth potential has vital significance for lowing the cost of culturing and maintaining parent fish. In this study, a single nucleotide polymorphism (SNP) (g.1597C>A) and a 4-bp insertion-deletion (indel) (g.1609–1612, CTTC) in intron 3, and three synonymous SNPs (g.1630A>T, g.1669A>T and g.1672C>T) in exon 4 were identified in the growth hormone (GH) gene of common carp. Furthermore, a polymerase chain reaction-single strand conformation (PCR-SSCP) approach was constructed. Four haplotypes (H1, H2, H3 and H4) and ten diplotypes (H1H1, H2H2, H3H3, H4H4, H1H2, H1H3, H1H4, H2H3, H2H4 and H3H4) were detected in three carp breeds, including Heilongjiang carp Cyprinus carpio haematopterus (YL), a selective strain of German mirror carp Cyprinus carpio L. mirror (JL), and a cold-resistant strain of Purse red carp Cyprinus carpio var. wuyuanensis (HL). To reveal the associations of each diplotype with growth traits around the first overwintering period, a total of 747 individuals from YL (n = 263), JL(n = 229), and HL (n = 255) were genotyped. We found that fish with the H2H2 diplotype exhibited higher body weight (BW) (135, 325, 385 and 445 d) and net weight (NW) (445 d) than those with the H1H1, H1H2 and H2H3 diplotypes in YL (P < .05). In HL, there was a significantly lower overwintering weight loss rate (WLR) at 325 d and higher BW385, BW445 and NW445 in fish with the H2H2 diplotype than in those with the H1H2, H1H3, H2H3, H2H4, H3H3 and H4H4 diplotypes (P < .05). Taken together, these data unravel a novel H2H2 diplotype with positive effects on body weight traits around the first overwintering period, which should be used as a potential marker to improve accuracy of selection in common carp in Northeast China.

Genetic appraisal of growth traits in Iranian native Ghezel sheep using random regression models

This research was carried out to estimate the genetic parameters of the body weight traits of the Ghezel sheep using three different random regression models. The used data were 39,288 test-day records collected from 13,378 animals at Ghezel Sheep Breeding Station in Miandoab, West Azerbaijan Province, Iran from 1994 to 2012. Fixed effects in models included type of birth (single, twin) and year of birth (1994-2012). The weight as a function of age in the days of weighting was considered as the fixed regression of orthogonal polynomial. The random effects of the basic model were direct genetic and direct permanent environment. Maternal genetic and maternal permanent environment effects were added to it respectively. In the basic model, increasing the order of fit for the fixed regression, direct genetic and direct permanent environment effects, increased the accuracy of the model. Adding the maternal permanent environmental effect to the model and increasing the order of fit increased the accuracy of the model. However, adding the maternal additive genetic effect to the model and increasing the order of fit for this effect, decreased the model accuracy. Direct heritability for birth weight and weight at 90, 180, 270, and 360 days of age were: 0.30, 0.22, 0.39, 0.38, and 0.55, respectively. These heritability estimates reduced after birth and reached the lowest amount for body weight at 20 days of age; however, after that, they increased as the age increased (this increase was not uniform and had some fluctuations). The direct additive genetic correlations between the traits of weight at 90 days of age and the weight at 180 days of age was the highest (0.955) and between the birth weight and 180 days of age was the lowest (0.072). These correlations between adjacent age groups were closer than the remote age groups. The value of the direct genetic, direct permanent environment, maternal permanent environment, and the phenotypic variances for birth weight was the lowest and increased by increasing of the age (maximum was for weight of 360th day of age).

Mapping of QTL for chicken body weight, carcass composition, and meat quality traits in a slow-growing line

Slow-growing chicken lines are valuable genetic resources for the development of well-perceived alternative free-range production. While there is no constraint on increasing growth rate, breeding programs have to evolve in order to include new traits improving the positioning of such lines in the growing market for parts and processed products. In this study, we used dense genotyping to fine map QTL for chicken growth, body composition, and meat quality traits in view of developing new tools for selection of a slow-growing line. The dataset included a total of 836 birds (10 sires, 87 dams, 739 descendants) and 40,203 SNP. QTL for the 15 traits analyzed were detected by 3 different methods, i.e., linkage and linkage disequilibrium haplotype-based analysis (LDLA), family-based single marker association (FASTA), and Bayesian multi-marker regression (Bayes Cπ). After filtering for QTL redundancy, we found 16, 16, and 9 QTL when using the FASTA, LDLA, and Bayes Cπ methods, respectively, with a threshold of 2.49 × 10-5 for FASTA and LDLA, and a Bayes factor of 150 for the Bayes Cπ analysis. They comprised 17 QTL for body weight, 9 QTL for body composition, and 15 QTL for breast meat quality or behavior at slaughter. The 3 methods agreed in the detection of highly significant QTL such as that detected on GGA24 for body weight at 3, 6, and 9 wk, and the 2 QTL detected on GGA17 and GGA18 for breast meat yield. Several significant QTL were also detected for the different components of breast meat quality. This study provided new locations for investigation in order to improve our understanding of the genetic architecture of growth, carcass composition, and meat quality in the chicken and to develop molecular tools for the selection of these traits in a slow-growing line.

Short communication: Estimation of genetic trends for body weight traits in Markhoz goat at different ages

The objective of the present study was to estimate genetic trends for body weight at different ages in Markhoz goat, including birth weight (BW, n = 4758), weaning weight (WW, n= 3685), 6-month weight (6MW, n = 3420), 9-month weight (9MW, n = 3032) and 12-month weight (12MW, n = 2697). Data and pedigree information were collected from 1992 until 2014 at the Breeding Center of Markhoz goat, Sanandaj, Iran. The GLM procedure of SAS was used for selecting the variables and identifying significant fixed effects in the equation of model. Various animal models were applied for genetic analysis and the best model was determined based on Akaike information criteria (AIC). Breeding values of animals were predicted using Wombat program. Genetic trends were obtained by regressing the average predicted breeding values on birth year for each trait. Based on the best model, direct estimated genetic trends were positive and significance for WW, 6MW, 9MW and 12 MW were 15.51, 26.28, 58.36 and 76.70 g/year, respectively (p&lt;0.001). Maternal genetic trend for BW and WW were 0.61 and 5.47 g/year, respectively (p&lt;0.01). The low and moderate generic trends obtained in the present study, indicated the possibility of growth traits improvements through genetic selection at all ages in Markhoz goat.

Two insertion/deletion variants in the promoter region of the QPCTL gene are significantly associated with body weight and carcass traits in chickens.

Glutaminyl-peptide cyclotransferase-like (QPCTL) is an isoenzyme of glutaminyl-peptide cyclotransferase (QPCT). QPCTL and QPCT catalyze the formation of N-terminal modified pyroglutamate-fractalkine and the chemokine CCL2. The objective of this study was to investigate the association between insertions/deletions in the chicken QPCTL promoter region with growth traits in chickens. We first detected two insertion/deletion variants of QPCTL via whole-genome resequencing analysis of DNA samples from Xichuan chickens. A total of 1896 individuals from 12 breeds were genotyped for 52- and 224-bp insertions/deletions. We found two novel insertions/deletions in the promoter region of the chicken QPCTL gene and studied their association with chicken body weight and carcass traits. Our findings show that QPCTL can be a molecular marker for chicken genetics and breeding programs.

Principal Component Analysis of Morphometric Traits of West African Dwarf Goats

The study was conducted to evaluate the principal component analysis of phenotypic attributes of West African Dwarf (WAD) goat. Data collected on the live body weight and twelve morphometric traits of the goats which were categorised into four age groups based on their dentition. The age groups were: less than 2years old, 2- 3years old, 3-4 years old and 4 years old. The data were subjected to a PCA and Cluster analyses using the multivariate procedure components of SAS (2003). Result revealed that highest values of morphometric traits were obtained in goats that of 4 years old. The rate of increase in body weight and other morphometric traits was high in age group of ˂2 years to age 2-3years compared to differences observed in others across the age group. Heart Girth had the highest correlation with body weight. Foreleg, neck, ear and hind leg lengths; wither height and rump height were weakly correlated with the body weight of the goats. Result revealed that two Principal components were retained in the first age group (age group˂2years) which accounted for 72.99% of the total variation. The first PC alone accounted for 63.13% of the total variation while PC2 accounted for the remaining 9.86%. From this study, it was concluded that there is interdependence among body weight and morphometric traits and that morphometric traits can be used in predicting live weight of WAD goats; PCA and Cluster could be exploited in breeding and selection programmes to acquire highly coordinated animal bodies using fewer measurements.

Polymorphisms in GnRHI and GnRHII genes and their association with egg production and egg quality traits in chicken

ABSTRACT 1. Two candidate genes, namely, Gonadotropin releasing hormone I (GnRHI) and Gonadotropin releasing hormone II (GnRHII) play pivotal roles in ovulation and egg production in chicken. The objective of this study was to explore polymorphism in these genes and to estimate the effects of polymorphism of these two genes on egg production and egg quality traits in White Leghorn laying hens. 2. Single strand conformation polymorphism followed by sequencing was performed to detect polymorphism in these genes. 3. The coding regions of the GnRHI and GnRHII genes were found to be polymorphic. In the GnRH1 gene, 12 haplotypes were determined, of which the h1 haplotype was predominant and the h5, h9 and h11 haplotypes were the least frequent ones. In the GnRHII gene, eight haplotypes were found, of which the h1 haplotype was the most frequent and the h6 was the least frequent haplotype in the White Leghorn population. 4. The haplogroups of GnRHI had a significant effect on body weight and egg production up to 64 weeks of age, yolk content, Haugh units and egg shell parameters. The h1h2 haplogroup of the GnRHI gene showed the highest egg production, with 211.0 ± 24.3 eggs up to 64 weeks of age, while the highest yolk content and Haugh unit was found in h3h10 haplogrouped birds. The haplogroups of GnRHII had a significant effect on age at sexual maturity (ASM) where the shortest ASM was found in the h1h4 birds (147.3 ± 5.9 d) and the longest ASM was observed in the h1h3 birds (160.6 ± 23.4 d). 5. It was concluded that GnRHI and GnRHII genes are polymorphic and have a significant effect on body weight, egg production and egg quality traits in White Leghorn laying hens.

A TRIAL TO DETECT THE EFFECT OF STRAIN AND DIFFERENT SOURCES OF DRINKING WATER ON SOME PRODUCTIVE TRAITS IN BROILER CHICKS

The main goal of this experiment was to evaluate the effect of broiler strain and source of drinking water on some performance traits (body weight and carcass traits). Sample of water were taken from two different location sources, Giza governorate (as Nile water) and Qalubia governorate (as well water or ground water). Three different broiler strains were used in this study (Arbor acres, Hubbard and Cobb). Lead concentration (as a heavy metal element) and bacteriological analysis (total bacteria and fecal coliforms) in both water and carcass were carried out. The main results obtained can be summarized as follow: Arbor acres strain recorded the heaviest body at most ages compared to the other strains, the difference was highly significant at 5 and 6 weeks of ages. Total bacteria were significantly high in ground water compared to Nile water. Conversely, Coliforms bacteria count was significantly high in Nile water compared to ground water source. Regardless strain type, high positive correlation between lead concentration in drinking water and lead concentration in liver, kidney and carcass weight was observed

GENETIC PARAMETERS FOR GROWTH PERFORMANCE TRAITS OF EGYPTIAN BARKI LAMBS USING RANDOM REGRESSION MODEL

Variance components and genetic parameters for growth traits were estimated for Barki lambs using the average information REMLF90 (AIREMLF90). A total of 3205 Barki lambs’ records over the period from 1984 to 2017 from experimental Borg Al-Arab station belonging to Animal Production Research Institute (APRI) were analyzed by fitting Random Regression Model (RRM) with Legendre polynomials (LPs) for body weight traits from birth up to 480 days. Gender, type of birth, year, season and age of dam were considered as fixed effects in addition to the fixed regression on Legendre polynomials, while random regression of additive genetic and permanent environmental effects were considered as random factors in the model. The results showed that all fixed factors and some interactions were significant for all studied traits (P<0.05). Quadratic equation was the best description for growth curve. Additive genetic and permanent environment variances ranged from 0.88 to 6.08 and from 0.88 to 15.33 for birth and thirteen months weights, respectively. Additive genetic and permanent environment covariances ranged from 0.05 to 16.06 and from 0.08 to 9.20 for birth with six months weights and for weaning with ten months weights, respectively. Direct and total heritabilities ranged from 0.05 to 0.41 and from 0.08 to 0.74 for four months and birth weights, respectively. Additive, genetic and phenotypic correlation coefficients were the lowest between birth weight with other studied traits and the highest between ten months weight with other studied traits. Phenotypic variances were oscillated between 2.27 for birth weight to 22.56 for seven months weight, while, residual variances were oscillated between 0.06 for birth weight to 14.05 for four months weight. Therefore, ten months of age recommended to be the best criterion for selecting Egyptian Barki lambs for meat production.

Effects of dietary curcumin supplementation on seminal quality indices and fertility rate in broiler breeder roosters

ABSTRACT 1. Decreased semen quality is an underlying contributor to age-related subfertility in broiler breeder roosters. This study investigated the effects of dietary curcumin (derived from turmeric) supplementation as an antioxidant source on semen quality and fertility in broiler breeder roosters. 2. Twenty-eight Ross 308 roosters were randomly allotted to four groups with seven birds in each and were fed a standard diet supplemented with different levels of curcumin at 0 (C0), 10 (C10), 20 (C20) and 30 (C30) mg/bird per day from 48 through to 61 weeks of age. Body weight and semen quality traits were evaluated on a weekly basis and seminal concentrations of malondialdehyde (MDA) as a measure of antioxidation status were quantified at one-week intervals during the first 11 weeks of the trial (48–59 weeks of age). Semen samples from last 2 weeks (60 and 61 weeks of age) were used to artificially inseminate to assess the sperm-egg penetration (SP) in perivitelline membrane and fertility rates. 3. Except for body weight and ejaculate volume, other characteristics, including semen concentration, total sperm production, progressive motility and plasma membrane integrity were linearly improved by the increasing levels of curcumin supplementation (P < 0.01). However, dietary curcumin levels were linearly and quadratically associated with decreased seminal concentration of MDA (P < 0.01 and P < 0.03), percentage of abnormal sperm (P < 0.01 and P < 0.07) and increased plasma membrane functionality (P < 0.01 and P < 0.04), respectively. The SP holes in perivitelline membrane were increased in a linear and quadratic manner in response to increasing levels of curcumin (P < 0.01). Moreover, fertility rate was linearly improved (P < 0.01) as the dosage of curcumin increased, and resulted in 8, 12 and 14% improvements in the birds fed C10, C20 and C30, compared to C0, respectively. 4. In conclusion, the results showed that increasing levels of dietary supplementation of curcumin was associated with beneficial effects on semen quality indices and fertility rate in aged broiler breeder roosters.

A multiallelic indel in the promoter region of the Cyclin-dependent kinase inhibitor 3 gene is significantly associated with body weight and carcass traits in chickens.

Many studies have reported that cyclin-dependent kinase inhibitor 3 (CDKN3) is involved in the cell cycle. However, the function of CDKN3 has not been well elucidated in organisms. In this study, a multiallelic indel caused by a 19-bp fragment and a 2 × 19bp fragment was shown for the first time to be inserted into the promoter of the CDKN3 gene in 1994 chickens from 9 different breeds. In addition, 6 genotypes (C5C5, C4C4, C3C3, C4C5, C3C4, and C3C5) were observed (C3C3, C4C4, C5C5 have 3 × 19bp, 4 × 19bp, and 5 × 19bp, respectively). Among these genotypes, the C4C4 genotype was the most dominant genotype in 9 breeds. The results of χ2 analysis of CDKN3 gene in different breeds showed that there were significant differences in the distribution of genotypes among different cultivars (P < 0.01). In addition, association study with F2 chicken resource population which produced by Anka and Gushi chickens showed that the C3C4 genotypes had the greatest semi-evisceration weight (SEW, 1163.94 ± 46.84), evisceration weight (EW, 964.15 ± 41.16), head weight (HW, 45.55 ± 1.43), claw weight (CW, 63.42±2.86), wing weight (WW, 129.15±5.48), liver weight (LW, 29.96±1.27), carcass weight (cW, 1286.96±49.53), weight at 10 (1190.68±45.68) and 12 (1430.65±54.45) wk, followed by C3C3, C4C4, C5C5, C4C5, whereas C3C5 genotypes having the lowest SEW (989.21±47.71), EW (841.38±40.55), HW (41.03±1.46), CW (54.36±2.81), WW (116.31±5.39), LW (27.31±1.25), cW (1093.29±49.99), weight at 10 (1036.10±44.99) and 12 (1246.28±53.59) wk. Expression levels of CDKN3 in breast muscle of chickens with C4C4 (0.72±0.02), C3C3 (0.95±0.41), and C4C5 (0.74±0.13) genotypes were significantly lower than those with C5C5 (1.80±0.01) and C3C5 (2.14±0.17) genotypes (P < 0.05). In conclusion, we investigated the effect of a multiallelic indel in the CDKN3 gene on the economic traits of chickens, and this indel was significantly associated with growth and carcass traits in chickens. Collectively, our findings provide useful information about the repeat sequence indel in the promoter region of the CDKN3 gene as a potential molecular marker for chicken breeding.

Genome wide association study of body weight and feed efficiency traits in a commercial broiler chicken population, a re-visitation

Genome wide association study was conducted using a mixed linear model (MLM) approach that accounted for family structure to identify single nucleotide polymorphisms (SNPs) and candidate genes associated with body weight (BW) and feed efficiency (FE) traits in a broiler chicken population. The results of the MLM approach were compared with the results of a general linear model approach that does not take family structure in to account. In total, 11 quantitative trait loci (QTL) and 21 SNPs, were identified to be significantly associated with BW traits and 5 QTL and 5 SNPs were found associated with FE traits using MLM approach. Besides some overlaps between the results of the two GWAS approaches, there are considerable differences in the detected QTL. Even though the genomic inflation factor (λ) values indicate that there is no strong family structure in this population, using models that account for the existing family structure may reduce bias and increase accuracy of the estimated SNP effects in the association analysis. The SNPs and candidate genes identified in this study provide information on the genetic background of BW and FE traits in broiler chickens and might be used as prior information for genomic selection.

Genetic parameters and inbreeding effects for production traits of Thai native chickens

ObjectiveEstimate genetic parameters, the rate of inbreeding, and the effect of inbreeding on growth and egg production traits of a Thai native chicken breed Lueng Hang Kao Kabinburi housed under intensive management under a tropical climate.MethodsGenetic parameters were estimated for weight measured at four weekly intervals from body weight at day 1 (BW1D) to body weight at 24 weeks (BW24) of age, as well as weight at first egg, age at first egg (AFE), egg weight at first egg, and total number of eggs (EN) produced during the first 17 weeks of lay using restricted maximum likelihood. Inbreeding depression was estimated using a linear regression of individual phenotype on inbreeding coefficient.ResultsDirect additive genetic effect was significant for all traits. Maternal genetic effect and permanent environmental hen effects were significant for all early growth traits, expect for BW24. For BW24, maternal genetic effect was also significant. Permanent environmental hen effect was significant for AFE. Direct heritabilities ranged from 0.10 to 0.47 for growth traits and ranged from 0.15 to 0.16 for egg production traits. Early growth traits had high genetic correlations between them. The EN was lowly negatively correlated with other traits. The average rate of inbreeding for the population was 0.09% per year. Overall, the inbreeding had no effect on body weight traits, except for BW1D. An increase in inbreeding coefficient by 1% reduced BWID by 0.09 g (0.29% of the mean).ConclusionImprovement in body weight gain can be achieved by selecting for early growth traits. Selection for higher body weight traits is expected to increase the weight of first egg. Due to low but unfavorable correlations with body weight traits, selection on EN needs to be combined with other traits via multi-trait index selection to improve body weight and EN simultaneously.

Estimation of additive and non-additive genetic variances of body weight in crossbreed populations of the Japanese quail

A major part of the growth performance in birds is the result of the combined effects of genes, including the general and specific combining ability that requires the design of an optimal mating system. The aim of this study was to fit the best model for each body weight trait from hatch to 45 days and the estimation of the variance components and the genetic parameters for the body weight traits of a crossbred population. This crossbred population was created by 4 strains of Japanese quail, including the Italian Speckled (A), Tuxedo (B), Pharaoh (C), Texas A&M (D), and the body weights of the different combinations were analyzed by 24 models including the direct genetic effect, the non-additive genetic effects including dominance and epistatic effects, the maternal permanent environmental and maternal genetic effects. The selection of the best fit model of each trait was performed based on the deviance information criteria. The variance components were estimated using a single-trait animal model analyzed with Gibbs sampling. At the early stage of bird growth, maternal genetic and maternal permanent environmental effects had a considerable contribution to the best model, but the contribution of these effects reduced with an increase in the bird's age and the additive variance contribution increased. Adding non-additive genetic effects (dominance and epistasis) to the models significantly reduced the variance of the error and the additive genetic variance estimated with high accuracy. The estimated heritability of body weight traits for the body weights of hatch, 5, 10, 15, 20, 25, 30, 35, 40, and 45 d were 0.316, 0.170, 0.251, 0.153, 0.132, 0.164, 0.290, 0.425, 0.476, and 0.362, respectively. The ratio of maternal genetic and maternal permanent environmental was considerable especially on early age body weight but the ratio of dominance and epistatic variances on each of the body weight traits was less than 4.5% of the total variance, but led to a more accurate estimates of the direct additive genetic.

Polymorphisms in Exon-1 and Partial Intron-1 of Growth Hormone Gene and its Association with Body Weight Traits in Broiler

Polymorphisms in Exon-1 and Partial Intron-1 of Growth Hormone Gene and its Association with Body Weight Traits in Broiler