DGAT1 Gene Variants and Udder Biometry: A Genetic Association Study in Nigerian West African Dwarf Goats

Background The udder is vital for milk production in ruminants, including West African Dwarf (WAD) goats. Udder and teat characteristics influence milk yield and milking efficiency in these animals. The diacylglycerol O-acyltransferase 1 (DGAT1) gene has been identified as a key regulator of lipid metabolism and milk production traits across various species of animals. While DGAT1 polymorphisms have been extensively studied in other species, their association with udder morphology in West African Dwarf (WAD) goats remains unexplored. This study investigates DGAT1 polymorphisms and their relationship with udder traits to enhance genetic improvement strategies. Blood samples from 150 lactating WAD goats (1–8 years old) were collected across intensive, semi-intensive, and extensive management systems in Southwest Nigeria. Genomic DNA was extracted, and allele-specific PCR (AS-PCR) was used for SNP genotyping. Udder and teat traits were also measured. Associations between DGAT1 SNPs and udder traits were analyzed using linear and multiple regression models in R, with age and management system as covariates. Pearson correlations and Manhattan plots were used to visualize the SNP-trait relationships. Results No significant associations were found between the DGAT1 SNP and most udder traits, though suggestive associations were noted for udder depth and circumference (p < 0.10). The SNP effects varied, showing both positive and negative influences, but low R² values indicate that polygenic inheritance and environmental factors dominate. Age and management system significantly affected udder morphology, improving model accuracy, while genotype-trait correlations remained weak. Manhattan plots suggested that multiple loci within DGAT1 or nearby regulatory regions might contribute to trait variation, implying that DGAT1’s impact is likely moderated by genetic and environmental interactions. Conclusion This study found no strong association between the DGAT1 SNP and most udder traits but identified potential effects on udder depth and circumference. The low R² values suggest udder traits are polygenic and environmentally influenced. Including age and management system significantly improved model performance, emphasizing their critical role in udder morphology. While DGAT1 may contribute moderately, its effect likely depends on interactions with other genes and environmental factors.