The SCD gene is a significant component of the leptin signaling pathway. The SCD gene has also been suggested as a candidate essential gene that can change the ratio of saturated to unsaturated fatty acids in milk and increase the amount of conjugated linoleic fatty acid, which is thought to have anti-cancer properties. The current research was carried out on Holstein cows to determine the association between SCD (Stearoyl-Coenzyme A Desaturase) gene polymorphism and total milk yield at 305 days (TMY305) and daily milk yield (DMY). The polymorphism in the SCD gene was identified using the PCR-RFLP technique and the SatI restriction enzyme for genotyping at SNP c.878T>C in the exon 5. The TT, TC, and CC genotype frequencies were 0.21, 0.50, and 0.29 respectively. While the allele frequencies of T and C were 0.46 and 0.54, respectively. According to the Chi-square test results, the SCD/c.878T>C distribution was in Hardy-Weinberg disequilibrium (P<0.05). Statistical analysis indicated a significant association between the SCD gene polymorphism and TMY305 (P<0.05). The TC genotypes showed a higher mean TMY305 compared to the TT and CC genotypes.

Growth Hormone (GH) and Insulin like Growth Factor-I (IGF1) are members of somototrophine axis pathway. They play a role in key on several mechanisms such as postnatal growth, cell differentiation and metabolism. Due to their vital importance, polymorphisms on the genes coding are worth to be understood. In this study five native cattle breeds (Native Southern Yellow (NSY), South Anatolian Red (SAR), Anatolian Grey (AG), Native Black (NB), East Anatolian Red (EAR) were investigated by PCR-RFLP method for GH-MspI and IGF1-SnaBI loci. 198 and 194 samples were analyzed for GH-MspI and IGF1-SnaBI loci, respectively. In both two loci two alleles and three genotypes were observed. Predominant alleles were A and B for GH-MspI locus IGF1-SnaBI loci, respectively. Frequencies of A and B alleles were calculated between 0.400-0.875 and 0.846-0.903 for GH-MspI locus IGF1-SnaBI loci, respectively. While among investigated population only EAR population was at Hardy-Weinberg equilibrium for IGF1-SnaBI locus, for GH-MspI only, in SAR population no deviation from Hardy-Weinberg equilibrium.

This study was performed to determine the genotype and allele frequencies and the association between the leptin gene Sau3AI polymorphism and some performance traits in Simmental (n=60) and Brown Swiss (n=62) cattle in the province of Erzurum, Türkiye. Considering the allele frequencies in the population, the frequency of the A allele was 0.87 and the frequency of the B allele was 0.13 in Simmental cattle, and the frequency of the A allele was 0.94 and the frequency of the B allele was 0.06 in Brown Swiss cattle. According to the analysis conducted in the Simmental breed, the general averages were found to be 5422.4 ± 1901.74 kg for actual milk yield, 5626.6 ± 1475.85 kg for 305-day milk yield, 298.7 ± 84.80 days for lactation duration, and 18.5 ± 4.84 kg for daily milk yield. As a result of the analysis in the Brown Swiss breed, the general averages were 3917.8 ± 1584.38 kg for actual milk yield, 4614.3 ± 982.62 kg for 305-day milk yield, 254.9 ± 99.88 days for lactation duration, and 16.0 ± 3.82 kg for daily milk yield. According to the statistical analysis results, the impact of genotype on milk yield traits was insignificant in Simmental and Brown Swiss cattle.

Changing climatic conditions and growing population size lead take precautions against potential risks. Researchers who study in the agricultural field, including animal production, focus on finding out variants and breeds resistant to diseases and environmental stress. Detecting gene regions that affect resistance to diseases and environmental stress might increase the performance of the selection in favor of these traits. Due to these reasons in this study, five Turkish native cattle breeds were investigated for SNPs belonging to TLR2, NOD2, and IFNγ (using EcoRV, BsaHI ve HphI enzymes, respectively) reported to be associated with paratuberculosis previously. In total, 169 animals were analyzed from Native Southern Yellow (NSY= 29), East Anatolian Red (EAR=35), Anatolian Grey (AG=36), South Anatolian Red (SAR=34), and Native Black (NB=35). The genotype and allele frequencies were calculated with the PopGene32 program, and Khi square test was performed to determine whether the populations were in Hardy-Weinberg equilibrium (HWE). While at TLR2- EcoRV and NOD2- BsaHI loci, two alleles (A and C, C and T, respectively), IFNγ- HphI locus was found to be monomorphic for the G allele. For TLR2- EcoRV locus, the C allele was found as predominant except NB breed, and the C allele was predominant for all breeds at NOD2- BsaHI locus. However, in all breeds, NOD2- BsaHI locus was at HWE, for TLR2- EcoRV NSY and SAR breeds showed derivation from HWE.

This study was carried out on 114 Brown Swiss cattle reared in intensive conditions at Ataturk University Food and Livestock Application and Research Center and at the private cattle farm found in Erzurum province. Genotypic structures were examined in terms of Insulin-like growth factor (IGF)-II gene locus and the distribution of genotypes and allele frequencies of the cattle concerning the genes were determined. The identified Insulin-like growth factor (IGF)-II genotypes were associated with milk yield traits such as actual milk yield, 305-day, and daily milk yield. Insulin-like growth factor (IGF)-II genotypes were determined by using the Polymerase Chain Reaction (PCR)- Restriction fragment length polymorphism (RFLP) method from blood samples taken from the cattle. The CC, CT, and TT genotype frequencies of the Insulin-like growth factor (IGF)-II gene found in the population were 41 (34%), 65 (54%), and 14 (12%), and the frequency of the C allele and the T allele was found to be 0.61 and to be 0.39. The general averages of actual true milk yield, 305-day and daily milk yield were 4317±272.9 kg, 5277±240.7 kg and 18±0.9 kg, respectively, while CC, CT and TT genotypes 4168±515.8, 3756±321.7 and 5382±600.3 kg, respectively. As a result, correctly identified IGF-II genotypes were detected by using the PCR-RFLP method in the blood samples obtained from Brown Swiss cattle. Genotype and allele frequencies determined for IGF-II gene polymorphism can be considered sufficient to demonstrate the genotype diversity of the race. According to the Hardy-Weinberg genetic equilibrium test, the distribution of genotype frequencies of the cattle was observed in equilibrium.