Genetic Architecture of Abdominal Fat Deposition Revealed by a Genome-Wide Association Study in the Laying Chicken.

Fat has a high energy density, and excessive fatness has been recognized as a problem for egg production and the welfare of chickens. The identification of a genetic polymorphism controlling fat deposition would be helpful to select against excessive fatness in the laying hen. This study aimed to estimate genomic heritability and identify the genetic architecture of abdominal fat deposition in a population of chickens from a Dongxiang blue-shelled local breed crossbred with the White Leghorn.

Effects of Energy-Restricted Feeding during Rearing on the Performance, Uniformity, and Development of Rugao Layer Breeders at the Initiation of the Laying Period.

The aim of this study was to assess the effects of energy-restricted feeding during rearing on the performance, uniformity, and development of layer breeders at the initiation of the laying period. A total of 2400 8-week-old Rugao layer breeders were randomly assigned to one of five groups (480 pullets per group) with eight replicates and were fed one of five diets that were nutritionally equal with the exception of apparent metabolizable energy corrected for nitrogen (AME) content (2850, 2750, 2650, 2550, and 2450 kcal AME/kg) from 8 to 18 weeks of age. The daily amount of feed was restricted to the absolute quantity of the diet consumed by laying hens fed 2850 kcal AME per kg diet ad libitum (control).

Lipolytic gene DAGLA is targeted by miR-223 in chicken hepatocytes.

miR-223 is an important miRNA. It plays important roles in lipid metabolism by targeting related genes in mammals. It may be related to fatty liver in laying hens and its functions and target genes need further study.

Identification of potential genomic regions and candidate genes for egg albumen quality by a genome-wide association study.

Albumen quality is a leading economic trait in the chicken industry. Major studies have paid attention to genetic architecture underlying albumen quality. However, the putative quantitative trait locus (QTL) for this trait is still unclear.

Genome-wide association study provides insights into the genetic architecture of bone size and mass in chickens.

Bone size is an important trait for chickens because of its association with osteoporosis in layers and meat production in broilers. Here, we employed high density genotyping platforms to detect candidate genes for bone traits. Estimates of the narrow heritabilities ranged from 0.

Genetic architecture related to contour feathers density in an F resource population via a genome-wide association study.

The density of contour feathers is an important trait as it is closely related to heat dissipation in birds. Thus, identification of the major genes that control this trait will be useful to improve heat tolerance in chicken. So far, no GWAS study for the density of contour feathers in birds has been previously published; therefore, this study was aimed to identify genomic regions controlling the density of contour feathers.

Genetic evaluation of eggshell color based on additive and dominance models in laying hens.

Objective: Eggshells with a uniform color and intensity are important for egg production because many consumers assess the quality of an egg according to the shell color. In the present study, we evaluated the influence of dominant effects on the variations in eggshell color after 32 weeks in a crossbred population.

Methods: This study was conducted using 7,878 eggshell records from 2,626 hens.

Genetic architecture and candidate genes detected for chicken internal organ weight with a 600 K single nucleotide polymorphism array.

Objective: Internal organs indirectly affect economic performance and well-being of animals. Study of internal organs during later layer period will allow full utilization of layer hens. Hence, we conducted a genome-wide association study (GWAS) to identify potential quantitative trait loci or genes that potentially contribute to internal organ weight.

A genome-wide study to identify genes responsible for oviduct development in chickens.

Molecular genetic tools provide a method for improving the breeding selection of chickens (Gallus gallus). Although some studies have identified genes affecting egg quality, little is known about the genes responsible for oviduct development. To address this issue, here we used a genome-wide association (GWA) study to detect genes or genomic regions that are related to oviduct development in a chicken F2 resource population by employing high-density 600 K single-nucleotide polymorphism (SNP) arrays.

Genetic Architecture and Candidate Genes Identified for Follicle Number in Chicken.

Follicular development has a major impact on reproductive performance. Most previous researchers focused on molecular mechanisms of follicular development. The genetic architecture underlying the number of follicle, however, has yet not to be thoroughly defined in chicken.

Random regression analyses to model the longitudinal measurements of yolk proportions in the laying chicken.

Cubic spline function was used in a genetic evaluation to model the change of yolk proportion over the lay life. A total of 19,862 yolk proportion records of 2,324 hens was used. The evaluated submodels consisted of 3 to 6 knot models.

Genetic architecture of bone quality variation in layer chickens revealed by a genome-wide association study.

Skeletal problems in layer chickens are gaining attention due to animal welfare and economic losses in the egg industry. The genetic improvement of bone traits has been proposed as a potential solution to these issues; however, genetic architecture is not well understood. We conducted a genome-wide association study (GWAS) on bone quality using a sample of 1534 hens genotyped with a 600 K Chicken Genotyping Array.

Genome-Wide Association Studies for Comb Traits in Chickens.

The comb, as a secondary sexual character, is an important trait in chicken. Indicators of comb length (CL), comb height (CH), and comb weight (CW) are often selected in production. DNA-based marker-assisted selection could help chicken breeders to accelerate genetic improvement for comb or related economic characters by early selection.

Identification of Promising Mutants Associated with Egg Production Traits Revealed by Genome-Wide Association Study.

Egg number (EN), egg laying rate (LR) and age at first egg (AFE) are important production traits related to egg production in poultry industry. To better understand the knowledge of genetic architecture of dynamic EN during the whole laying cycle and provide the precise positions of associated variants for EN, LR and AFE, laying records from 21 to 72 weeks of age were collected individually for 1,534 F2 hens produced by reciprocal crosses between White Leghorn and Dongxiang Blue-shelled chicken, and their genotypes were assayed by chicken 600 K Affymetrix high density genotyping arrays. Subsequently, pedigree and SNP-based genetic parameters were estimated and a genome-wide association study (GWAS) was conducted on EN, LR and AFE.

Genome-wide association studies for feed intake and efficiency in two laying periods of chickens.

Background: Feed contributes to over 60 % of the total production costs in the poultry industry. Increasing feed costs prompt geneticists to include feed intake and efficiency as selection goals in breeding programs. In the present study, we used an F2 chicken population in a genome-wide association study (GWAS) to detect potential genetic variants and candidate genes associated with daily feed intake (FI) and feed efficiency, including residual feed intake (RFI) and feed conversion ratio (FCR).

Genome-wide association study dissects genetic architecture underlying longitudinal egg weights in chickens.

Background: As a major economic trait in chickens, egg weight (EW) receives widespread interests in breeding, production and consumption. However, limited information is available for underlying genetic architecture of longitudinal trend in EW. Herein, we measured EWs at nine time points from onset of laying to 60 week of age, and conducted comprehensive genome-wide association studies (GWAS) in 1,534 F2 hens derived from reciprocal crosses between White Leghorn and Dongxiang chickens.

Genetic parameters of feed efficiency traits in laying period of chickens.

Laying records on 1,534 F2 hens, derived from a reciprocal cross between White Leghorns and Dongxiang blue-shelled chickens, were used to estimate genetic parameters for residual feed intake (RFI), feed conversion ratio (FCR), daily feed intake (FI), metabolic BW (MBW), BW gain (BWG), and daily egg mass (EM) at 37 to 40 (T1) and 57 to 60 wk age (T2), respectively. Genetic analysis was subsequently conducted with the AI-REML method using an animal model. Estimates for heritability of RFI, FCR, and FI were 0.