The aim of study were to present relationships between birth weight of 94 Holstein calves with genotype structures of each sample’s Growth Hormone (GH) determined through PCR-RFLP method and to detect the population’s genetic variation by determining the genotype and allel frequency distribution. In the study, according to the analysis result, it was determined that Growth Hormone gene LL genotype was 41.9 kg, LL was 40.8 kg, and VV was 42.2 kg for the birth weight. A significant relationship between birth weight with GH genotypes could not be found. It was seen that the calf population is not stable according to Hardy-Weinberg genetic balance test.

Türkiye bitki çeşitliliği bakımından ender ülkeler arasındadır. Bu durumun bir örneği de ülke genelinde tohumdan yetişen ceviz çöğürlerindeki varyasyondur. Bu farklılığın ceviz ıslahında kullanılabilmesi için genetik materyalin ismine doğru olması ve aralarındaki genetik ilişkilerin belirlenmesi büyük önem taşımaktadır. Yapılan bu çalışmada Uşak ilinden seleksiyon ile elde edilmiş bazı ceviz genotiplerinde genetik çeşitliliğin moleküler markörler ile belirlenmesi amaçlanmıştır. Çalışmada 19 adet SRAP markör kombinasyonu kullanılmıştır. Bu markörlerden sayıları 2 ile 18 arasında değişen toplam 171 skorlanabilir bant elde edilmiş olup, bunların %77,2’si polimorfik olarak bulunmuştur. Markörlerden elde edilen bantların baz uzunlukları ise 100-1500 bp arasında değişim göstermiştir. Ceviz genotiplerine ait benzerlik oranı 0,21 – 0,85 arasında değişim göstermiştir. Çalışma sonucuna göre SRAP markör sisteminin ceviz genotipleri arasında genetik çeşitliliği belirlemede etkili şekilde kullanılabileceği tespit edilmiştir.

In this study, the effect of STAT5A gene was investigated on milk yield and components (fat, protein) in Jersey cows. Because, this gene is a member of the signal transducers and activators of transcription the factor (STAT) family and thought to be the impact on milk yield and components. As a material in the research, 100 Jersey cows raised in Samsun Karakoy State Farm were used. Milk samples were collected 12 times with one month intervals after calving, and these samples were performed by ultrasonic milk analyzer for milk fat and protein content. In addition, test day milk yield (TDMY) of each cow were also recorded in the control days. C/G polymorphism with PCR-RFLP method result in DNA isolation from blood samples taken from cows was determined at 8.exon at position 12195. Genotype distribution was detected as 69% CC, 28% CG and 3% GG. Allele frequencies were found as 0.83 for the C allele and 0.17 for G allele. As a result of the polymorphism identified in STAT5A gene, statistically no difference were detected among genotypes for TDMY, 305 day milk yield (305 DMY), milk fat and protein rates and milk fat and protein yield. As a result, no significant differences were found between the milk yield and compositions association with STAT5A