Association of The β-Casein and Lactoferrin Genes Polymhorphisms with Milk Protein in Friesian Holstein Cows.

Abstract

The purposes of this study were to identify the polymorphism of the β-casein and the lactoferrin genes and the association of genetic variants of the β-casein and the lactoferrin genes on protein yield, milk yield and SCC in Holstein-Friesian (HF) cows. The study was conducted on 282 heads of HF lactating cows coming from two managements of: 1) intensive at dairy breeding station of BPPT-SP Cikole, and 2) semi intensive of small dairy farmers in two villages of the KPSBU Lembang, Lembang District. Investigation on variant genotypes of the β-casein and the lactoferrin genes used PCR-RFLP method. Genotyping the β-casein gene with MspI restriction enzyme to all DNA samples produced only the BB genotype (100%), meaning this gene was monomorphic. While genotyping the lactoferrin gene with EcoRI restriction enzyme produced two genotypes, i.e. AA (65%) and AB (35%) genotypes. The AB genotype of the lactoferrin gene tended to produce higher milk protein than AA genotype, though the differences were statistically not significant (P>0.05). Both the AA and AB genotypes had inconsistency in controlling milk fat and milk yield. Further, the AB lactoferrin cows had a higher frequency in the classification of low somatic cells count (0.75), while the AA cows were at a higher frequency in the classification of high somatic cells count (0.60). It was concluded that the β-casein gene studied was monomorphic, so the effect in controlling milk protein had still not been known, while the AB genotype of the lactoferrin gene had a consistency in producing higher milk protein and lower somatic cells count compared to the AA genotype.

Perbaikan genetik sapi perah domestik dapat dilakukan antara lain melalui seleksi keunggulan pada gen yang diprediksi berasosiasi kuat dengan sifat produksi, kualitas susu dan ketahanan terhadap penyakit, khususnya seleksi untuk gen-gen yang mengontrol protein susu dan resistensi terhadap penyakit. β-kasein merupakan salah satu jenis dari fraksi kasein yang berpengaruh terhadap bentuk dan kestabilan butiran susu dan memiliki kontribusi sebesar 28.4% dari total protein susu, sedangkan laktoferin merupakan salah satu fraksi whey yang merupakan protein antimikrobia dalam susu yang berfungsi sebagai imunitas untuk melawan berbagai macam penyakit. Pemeriksaan dua atau lebih gen-gen protein susu (kasein dan whey protein) secara bersamaan bermanfaat untuk memperhitungkan pengaruh interaksi yang mungkin terjadi antara dua atau lebih gen haplotipe. Penelitian ini bertujuan untuk mengidentifikasi polimorfisme gen β-kasein dan laktoferin dan mengetahui konsistensi hubungan antara genotipe gen β-kasein dan laktoferin baik secara masing-masing maupun interaksi kedua gen dengan protein susu dan somatic cell count (SCC) pada sapi Friesian-Holstein (FH) laktasi pada dua kondisi pemeliharaan berbeda, yaitu intensif di stasiun bibit sapi perah BPPT-SP Cikole dan semi intensif di peternakan rakyat di bawah binaan KPSBU Lembang