Genome-wide association studies on growth performance trait of Nigerian indigenous Chicken genotypes

Uncovering genetic markers for growth and fat-tail traits in Kurdi sheep: associations with DGAT1 and PPARGC1B variants

Association of TGFβ2 gene polymorphism with growth performance and meat quality traits in Kampung Unggul Balitbangtan chickens under multienzyme supplementation

ABSTRACT Background and Aim: Improving growth performance and meat quality is a major objective in genetic improvement programs for indigenous poultry breeds. Kampung Unggul Balitbangtan (KUB) chickens are an improved Indonesian native breed with considerable potential for sustainable tropical poultry production. Transforming growth factor-beta 2 (TGFβ2) plays an important role in regulating skeletal muscle development, cell proliferation, and tissue remodeling; however, its genetic variation and association with economically important traits in KUB chickens remain unknown. This study aimed to characterize TGFβ2 gene polymorphisms and evaluate their associations with growth performance and meat quality traits in KUB chickens receiving dietary multienzyme supplementation. Materials and Methods: Twenty-five one-day-old male KUB chickens were assigned to five dietary treatments containing different combinations of phytase and protease and reared for 90 days. Growth performance was assessed using feed intake (FI), body weight (BW), feed conversion ratio (FCR), and carcass weight (CW). Meat quality traits, including pH, texture, cooking loss (CL), water holding capacity, and color characteristics (L*, a*, and b*), were evaluated after slaughter. Genomic DNA extracted from muscle tissue was analyzed using polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing to identify TGFβ2 polymorphisms. Functional enrichment of differentially expressed genes was investigated using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses. Results: Three TGFβ2 genotypes (CC, TC, and TT) were identified, with allele frequencies of 0.48 (C) and 0.52 (T). The TGFβ2 genotype was significantly associated with BW, CW, and FCR (p < 0.05), whereas FI was unaffected. Multienzyme supplementation significantly reduced CL, improved water holding capacity, and enhanced meat color characteristics without affecting pH or texture. Two exon single nucleotide polymorphisms, c.103C>T and c.99G>A, were identified, representing novel variants in KUB chickens. Functional enrichment analyses demonstrated significant involvement of extracellular matrix-receptor interaction, metabolic pathways, and biological processes related to muscle development and cell proliferation, supporting a nutrigenetic interaction between TGFβ2 polymorphism and enzyme supplementation. Conclusion: This study provides the first characterization of TGFβ2 polymorphisms in KUB chickens and demonstrates their association with growth performance and meat quality traits under multienzyme supplementation. The identified polymorphisms represent promising molecular markers for marker-assisted selection and precision nutrition strategies to improve productivity in indigenous tropical chicken populations.

Characterization of IGF1 gene marker as potential genes in improving growth performance of Indonesian goats

Background: Goat farming development begins with the availability of genetically and phenotypically superior livestock to ensure optimal productivity and reproduction. Aim: This study aimed to identify polymorphisms in the IGF1 gene and to evaluate their association with growth performance. Methods: A total of 105 goats were sampled, including 35 individuals from each of three Indonesian goat breeds: Peranakan Etawah (PE), Jawarandu, and Kacang, aged between 12 and 24 months. Growth parameters measured included body weight and morphometric characteristics. Genetic variation of the IGF1 gene was analyzed using Sanger sequencing. Morphometric data were analyzed using principal component analysis (PCA) in R software to explore variation patterns, while associations between IGF1 gene polymorphisms and growth traits were evaluated using analysis of variance (ANOVA). Results: Sequence analysis revealed significant nucleotide variations at certain positions, indicated by overlapping guanine (G) and thymine (T) chromatogram peaks, indicating a heterozygous genotype (G/T) at this locus. The IGF1 gene has diverse genotypes in all goat breeds, namely GG, GT, and TT. All genotypes were present except in the JW breed, where the TT genotype was absent. IGF1 gene diversity was significantly associated (P<0.05) with morphometric characteristics, including muzzle circumference, head length, ear length, ear width, rump length, and leg circumferenc. The GT genotype had the highest morphometric performance compared to the other genotypes. Conclusion: The IGF1 gene may serve as a potential candidate marker for marker-assisted selection (MAS) to improve the growth performance of Indonesian goats, although further validation is required.

Identification of candidate genes for reproductive traits in Chinese Holstein cattle using single-step genome-wide association study.

In dairy farming, reproductive efficiency is vital to both profitability and sustainability. However, years of selective breeding for increased milk yield have adversely affected reproductive potential. This study aimed to pinpoint genomic regions and identify potential candidate genes associated with reproductive traits in Chinese Holstein cattle. In this study, a single-step genome-wide association study (ssGWAS) was conducted using 33,202 phenotypic records from 16,379 animals, 55,244 pedigree records, and genomic data from 1,698 cows. These data were integrated into the ssGWAS analysis, resulting in a total pedigree structure of 21,635 animals. A total of 12 significant markers were identified for calving interval (IC), days open (DO), number of services per conception (NS), and conception rate (CR). Among these significant SNPs, 3 SNPs were for IC, 2 SNPs were for DO, 3 SNPs were for NS, and 4 SNPs were for CR. Several promising candidate genes located near these SNPs have been identified, including SFXN4, B3GAT2, GRK5, PRDX3, and MTHFD1L, highlighting their potential involvement in fertility-related biological processes. Furthermore, functional enrichment analysis identified significant enrichment of pathways associated with cell adhesion and embryonic development, suggesting a potential mechanistic role for DSG family members (DSG1, DSG2, DSG3, and DSG4) in fertility regulation. Collectively, our findings enhance understanding of the complex genetic basis of reproductive traits in dairy cattle and may offer a valuable set of genomic targets for precision breeding of Chinese Holsteins. Integrating these markers into genomic selection programs may contribute to genetic improvements in reproductive efficiency and support the long-term sustainability of dairy production.

First breed-pool whole genome sequencing of egyptian sheep: a comprehensive genomic atlas revealing diversity and candidate genes for production and adaptation

This research provides the first extensive breed‑pool whole‑genome sequencing (WGS) analysis across five Egyptian sheep populations: Barki (BAR), Rahmani (RAH), their crossbred offspring (CRS), Ossimi (OSI) and Awassi (AWI). To establish a genomic atlas of the genetic architecture of production and adaptation in Egyptian sheep, providing a baseline for future candidate gene discovery and conservation strategies. Through Illumina sequencing of 120 samples, we compiled a dataset exceeding 470 Gb, with mean coverage depths spanning 24.2x to 41.3x. Variant profiling, functional annotation, KEGG pathway analysis, and independent structural variant analysis were conducted. Phenotypic data were collected and validated through qRT-PCR gene expression analysis. Variant profiling revealed between 11.9 and 17.4 million SNPs per breed after stringent filtering. Heterozygosity patterns (population‑level estimates) differed substantially between groups, recorded at 60.41% in the CRS crossbred versus 74.92–85.01% in the purebred lines. Functional annotation identified conserved enrichment related to xenobiotic detoxification and lipid metabolism. KEGG pathway analysis prioritized the PPAR signalling pathway (map03320) and fatty acid metabolism (map01212) as highly significant (p < 0.0001). Independent structural variant analysis identified distinct genomic hotspots on chromosomes 2, 6 and 18, overlapping candidate genes; FABP4, KAP cluster and MSTN implicated in the regulation of fat deposition and muscle development. Phenotypic data confirmed a high degree of breed divergence (p < 0.001). RAH and CRS individuals reached higher body condition scores (BCS 4.31‑ 4.53) and increased fat deposition, whereas BAR was significantly leaner (BCS 2.53). The highest trimmed meat yields were observed in CRS (23.95 kg) and RAH (18.40 kg) (p < 0.001), with RAH also displaying the highest intramuscular fat content at 4.20%. qRT‑PCR validation showed elevated expression of lipogenic genes (ACACA, FASN and FABP4) in fat‑tailed breeds and differential expression of myogenic regulators (MSTN and IGF‑1) correlating with muscularity variations. The current findings establish a genomic atlas for the genetic architecture of production and adaptation in Egyptian sheep, providing a baseline for future genetic and conservation strategies. Formal selection signature analyses, such as XP‑EHH and iHS are recommended for subsequent studies.

Development and application of SNP chips in goat breeding: a mini review

Goats (Capra hircus) are among the world’s most important livestock, providing milk, meat, and fiber across diverse agro-ecological zones. Traditional breeding relying on pedigree-based estimated breeding values (EBVs) has driven steady genetic progress but is constrained by long generation intervals and limited accuracy for sex-limited or difficult-to-measure traits. High-throughput single nucleotide polymorphism (SNP) chips and genomic selection (GS) have transformed goat breeding by enabling early, accurate selection independent of phenotypic records. This review synthesizes the development of goat SNP chip platforms from the foundational 52 K GoatSNP50 BeadChip through high-density solid-phase arrays and low-cost liquid-phase capture panels, with emphasis on their relative performance, cost-effectiveness, imputation potential, and suitability for different breeding systems. In addition to genomic selection (GS), genome-wide association studies (GWAS), and genetic diversity assessment, we also discuss candidate-gene selection and marker-assisted selection (MAS) as practical intermediate approaches that remain relevant in many goat breeding programs. GS has achieved genomic estimated breeding value (GEBV) prediction accuracies of 0.35–0.79 for key production traits across multiple countries and breeds. GWAS has identified candidate genes for milk composition (DGAT1, CSN1S1), growth (PLAG1, HMGA2), reproduction (BMPR1B, GDF9), and fiber quality (KRT, KRTAP families). We compare GS with traditional BLUP-based approaches, assess economic benefits, and discuss key challenges including reference population construction, genotype imputation, inbreeding management via Optimum Contribution Selection (OCS), and multi-omics integration. Future directions include customized chip design, AI-assisted genomic prediction, climate adaptation breeding, and CRISPR/Cas9 gene editing for precision improvement.