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

Abstract

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.