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Effect of CSN1S1 Gene Polymorphism on the Lactation Curve Characteristics of Etawah Grade (PE) Goats 1. Faculty of Animal Science, Jenderal Soedirman University, Purwokerto Abstract Etawah Grade (PE) goats, a prominent dairy breed in Indonesia, exhibit high genetic diversity in the alpha s1 casein (CSN1S1) gene. While polymorphisms in this gene are known to affect milk yield in other breeds, their specific impact on the lactation curve pattern in PE goats has not been well-established. This study aimed to characterize and compare the lactation curves of PE goats based on their identified CSN1S1 haplotypes (AA, AF, and FF). A total of 98 lactating PE goats were genotyped using the PCR-RFLP method, and their weekly milk production was recorded. The data were segregated by haplotype, and the best-fit lactation curve model for each group was determined using polynomial multiple linear regression analysis in RStudio. The results revealed significant differences in the shape of the lactation curves among the haplotypes. For both AA and AF haplotypes, the curve was best described by a model including highly significant linear (p 0.001) and cubic (p 0.0163 for AA- p 0.001 for AF) components. This indicates a typical lactation pattern with distinct phases of rise, peak, and decline. In contrast, the lactation curve for the FF haplotype was significantly explained only by a strong linear component (p 0.001), with non-significant quadratic and cubic terms. This suggests a more persistent, straight decline in milk production without a characteristic peak. In conclusion, polymorphism in the CSN1S1 gene fundamentally influences the lactation dynamics in Etawah Grade goats. The AA and AF haplotypes are associated with a classic cubic lactation curve, whereas the FF haplotype corresponds to a simpler, linearly declining milk yield. Keywords: Etawah Grade goat, CSN1S1, genetic polymorphism, lactation curve, milk production, PCR-RFLP Topic: Animal Production |
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