Polimorfisme genetik growth hormone dan insulin-like growth factor-I serta efeknya pada pertumbuhan prasapih sapi potong di Indonesia

Penelitian ini bertujuan mengungkap polimorfisme gen growth hormone (GH) dan insulin-like growth factor-I (IGF-I) pada sapi potong di Indonesia. Bila polimorfisme kedua gen ini berhasil dideteksi pada bangsa-bangsa sapi potong di Indonesia yang diamati, dan efeknya pada pertumbuhan dapat dipelajari maka kemungkinan dapat digunakan sebagai pemarkah genetik untuk perbaikan pertumbuhan bangsa sapi potong yang diteliti. Sampel darah diambil dari populasi sapi Bali di Pusat Pembibitan Sapi Bali milik P3Bali, di luar wilayah P3Bali di pulau Bali, dan di luar pulau Bali (Kalimantan Selatan), berturut-turut sebanyak 111, 85 dan 46 sampel darah. Sampel darah diambil pula dari populasi sapi PO, SIMPO dan LIMPO di wilayah Daerah Istimewa Yogyakarta, berturut-turut sebanyak 43, 44, dan 42 sampel. Identifikasi polimorfisme gen GH dilakukan dengan mendigesti fragmen DNA spesifik berukuran 211 bp yang merentang dari intron keempat (49 bp) ke exon kelima (162 bp) menggunakan enzim AluI, sedangkan identifikasi polimorfisme gen IGF-I dilakukan dengan mendigesti fragmen DNA spesifik berukuran 249 bp pada 5â��-flanking regionâ�� (merentang dari 483 bp sampai 732 bp pada sisi 5â�� dari kodon pertama pada exon pertama) dari gen IGF-I menggunakan enzim SnaBI. Hasil penelitian menunjukkan bahwa gen IGF-I ditemukan tidak polimorfik pada bangsa-bangsa sapi potong di Indonesia yang diteliti, sedangkan gen GH ditemukan tidak polimorfik pada sapi Bali, namun polimorfik pada bangsa sapi PO, SIMPO dan LIMPO, dimana sapi SIMPO memiliki tingkat polimorfisme tertinggi. Efek polimorfisme gen GH terhadap sifat-sifat pertumbuhan pedet SIMPO menunjukkan bahwa pedet SIMPO bergenotip LV cenderung tumbuh lebih baik hingga umur 2 bulan dibandingkan pedet SIMPO bergenotip LL. Dengan mengabaikan kemungkinan mutasi gen dimasa datang, gen GH dan IGF-I yang tidak polimorfik pada sapi Bali dapat digunakan sebagai indikator tambahan untuk mempelajari kemurnian sapi Bali. Gen GH polimorfik pada populasi sapi SIMPO dapat digunakan sebagai pemarkah genetik untuk perbaikan pertumbuhannya hingga umur 2 bulan. The study was conducted to reveal polymorphism of growth hormone (GH) and insulin-like growth factor-I (IGF-I) genes of beef cattle in Indonesia. If the polymorphic of these genes could be detected then its effect on growth could be studied and then it could be used as the genetic marker for selection of preweaning growth rate of beef cattle in Indonesia. Blood samples were taken from three population of Bali cattle: Bali cattle which located in Bali Cattle Improvement Centre, Bali cattle at Bali island, and Bali cattle at South Kalimantan, and were 111, 85 and 46 samples respectively. Blood samples were also taken from Ongole grade (PO) cattle, SIMPO cattle and LIMPO cattle in Special Region of Yogyakarta and were 43, 44 and 42 samples respectively. The identification of GH gene polymorphism was conducted by digested the DNA fragment of 221 bp extended from the fourth intron region (49 bp) to fifth of exon (162 bp) by AluI enzyme, while for IGF-I gene polymorphism the sample DNA fragment of 249 bp which located in 5â��flanking region (extended from 483 bp to 732 bp 5â�� to the first codon of the first exon) of the bovine IGF-I gene was digested by SnaBI enzyme. The results indicated that IGF-I gene was not polymorphic of beef cattle in Indonesia, while GH gene was not polymorphic in Bali cattle, but it was polymorphic in PO, SIMPO dan LIMPO cattle, where SIMPO cattle was the most polymorphic. The effect of GH polymorphism on growth traits indicated that SIMPO calf which LV genotype tend to grow faster until 2 months of age than LL genotype. By neglected the possibility of gene mutation in the future, the non polymorphic of GH and IGF-I genes in Bali cattle can be used as an aditional indicator to study the purity of Bali cattle. The polymorphic of GH gen in SIMPO cattle population can be used as genetic marker for preweaning growthâ��s improvement.