Analisis Keragaman Gen CSN1S1 dan Asosiasinya terhadap Kualitas Susu Kambing Silangan Saanen dan Peranakan Etawah (Sapera)

Abstract

Susu kambing telah mendapatkan perhatian sebagai alternatif penting untuk susu sapi di Indonesia, khususnya karena manfaat nutrisinya yang superior dan kemampuannya untuk dicerna dengan lebih mudah oleh tubuh manusia. Dua bangsa kambing, yaitu Kambing Peranakan Etawah dan Saanen menunjukkan potensi besar dalam meningkatkan produksi susu di Indonesia. Balai Penelitian Ternak Ciawi mengembangkan kambing Silangan dari kedua bangsa ini yang dinamakan Sapera. Salah satu fokus utama dari penelitian terkait susu kambing adalah gen CSN1S1, yang memiliki peran krusial dalam menentukan kualitas protein dalam susu. Memahami variasi dan keragaman dari gen ini, peluang untuk mengoptimalkan produksi susu kambing, baik dari segi kualitas maupun kuantitas. Penelitian menggunakan sampel dari tiga bangsa kambing - Sapera, Saanen, dan Peranakan Etawah. Tujuannya adalah menganalisis keragaman genetik dari gen CSN1S1 dan mengevaluasi hubungannya dengan kualitas susu. Studi ini dilaksanakan dalam dua fase. Pada fase pertama, diambil sampel darah dari 66 kambing Sapera, 15 kambing Saanen, dan 14 kambing PE yang berasal dari Balai Penelitian Ternak, Ciawi. Ekstraksi DNA dari sampel darah dilakukan dengan metode modifikasi DNA Kit Geneaid. DNA yang telah diekstraksi diperbanyak melalui proses PCR dan variasi genetik gen CSN1S1 dianalisis dengan teknik Sanger Sequencing. Pada fase kedua, diambil sampel susu dari 66 kambing Sapera yang sedang berada dalam periode laktasi. Komposisi susu dianalisis dengan alat Lactoscan Milk Analyzer, dan data produksi susu harian dihitung dari total produksi susu di pagi dan sore hari saat pengambilan sampel. Hubungan antara genotipe dengan produksi dan komposisi susu dianalisis dengan menggunakan model General Linear Model. Hasil penelitian menunjukkan ada 15 mutasi yang terjadi pada area parsial intron 11, ekson 12, dan parsial intron 12. Mutasi yang terjadi pada intron 11 terdiri dari 1 insersi 4 bp pada titik g.10090 – g. 10093 Ins AGAA dan 10 mutasi titik atau single nucleotide polymorphism (SNP) pada g. 10098 C>G, g.10112 C>T, g. 10129 C>A, g.10177 G>A, g.10180 A>C, g. 10181 T>A, g.10188 T>C, g.10197 C>T, g.10202 T>C, dan g.10220 C>T. Mutasi yang terjadi pada ekson 12 terdiri dari 2 SNP yaitu g.10243 G>A dan g.10250. Mutasi yang terjadi pada intron 12 yaitu 2 SNP g.10277 G>A dan g.10283 T>G. Mutasi g. 10098 C>G pada intron 11 ditemukan berasosiasi terhadap jumlah produksi susu, yield protein, yield lemak, yield laktosa, dan yield solid non fat (SNF). Mutasi pada g. 10181 T>A pada intron yang sama juga berasosiasi terhadap persentase lemak, laktosa dan total solid pada susu kambing sapera. Mutasi yang terjadi pada daerah ekson 12 dan lainnya tidak berasosiasi terhadap kualitas susu pada penelitian ini. Ditemukan adanya perubahan asam amino dari Arginin menjadi Lysin yang disebabkan oleh mutasi di titik g. 10243 G>A.

Goat milk has gained attention as an important alternative to cow's milk in Indonesia, especially due to its superior nutritional benefits and its easier digestibility by the human body. Two goat varieties, namely the Etawah Grade Goat and the Saanen show great potential in increasing milk production in the country. The Ciawi Livestock Research Center developed a hybrid goat from these two breeds called Sapera. A primary focus of goat milk research is the CSN1S1 gene, which plays a crucial role in determining the quality of protein in milk. By understanding the variations and diversity of this gene, there is an opportunity to optimize goat milk production, both in terms of quality and quantity. This study used samples from three types of goats - Sapera, Saanen, and Etawah Grade. The aim was to analyze the genetic diversity of the CSN1S1 gene and evaluate its relationship with milk quality. The study was conducted in two phases. In the first phase, blood samples were taken from 66 Sapera goats, 15 Saanen goats, and 14 Etawah Grade goats from the Ciawi Livestock Research Center. DNA extraction from the blood samples was done using a modified DNA Kit Geneaid method. The extracted DNA was amplified through the PCR process, and the genetic variation of the CSN1S1 gene was analyzed using the Sanger Sequencing technique. In the second phase, milk samples were taken from 66 Sapera goats in their lactation period. The milk composition was analyzed using the Lactoscan Milk Analyzer, and daily milk production data was calculated from the total milk production in the morning and evening during sample collection. The relationship between genotype and milk production and composition was analyzed using the General Linear Model. The research results showed that there were 15 mutations occurring in the partial intron 11 area, exon 12, and partial intron 12. The mutations in intron 11 consisted of a 4 bp insertion at point g.10090 – g.10093 Ins AGAA and 10 point mutations or single nucleotide polymorphism (SNP) at various points. Mutations in exon12 consisted of 2 SNPs. The mutations in intron 12 were 2 SNPs. The mutation g.10098 C>G in the intron 11 was found to be associated with milk production, protein yield, fat yield, lactose yield, and solid non-fat (SNF) yield. The mutation at g.10181 T>A in the same intron was also associated with the percentage of fat, lactose, and total solids in Sapera goat milk. Mutations in exon 12 and elsewhere were not associated with milk quality in this study. However, an amino acid change from Arginine to Lysine was found due to the mutation at point g.10243 G>A.