Abstract
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.

Key words: Breed; Goats; Growth performances; IGF1 gene; Sanger sequencing.