This research was carried out to determine the effect of a specific single nucleotide polymorphism (SNP) region in exon 10 of the growth hormone receptor (GHR) gene on milk production traits in Jersey and Holstein cows raised in Turkey. Milk samples were recorded as a test day milk yield (TDMY) and an adjusted based 305 d milk yield (305-DMY). Also, milk component traits were detected. Based on the scope of this study, a total of 748 dairy cows, including 305 Holsteins raised in the Marmara Region and 163 Holstein and 280 Jersey raised in the Black Sea Region, were genotyped for the GHR gene using the RFLP-PCR technique. Jersey cows carrying the GG genotype (5.24 %) were associated with higher fat content (P<0.05). Jersey cows with GG and AG also had a higher protein content (3.44 % and 3.38 %, respectively) (P<0.05). Similarly, the protein content was the highest in Holstein cows with the GG genotype (3.46 %) (P<0.01), whereas Holstein cows having AA genotypes displayed higher TDMY (24.64 kg/d) (P<0.05) and 305-DMY (8472.4 kg) (P<0.01). The estimated increase in milk protein and fat contents due to the G allele was 0.07 % and 0.22 % in the Jersey breed, respectively. On the other hand, allele A was highly related to an increase in protein yield and 305-DMY of 0.04 and about 675 kg in the Holstein breed, respectively. The GHR gene should be considered as a potential candidate gene in marker-assisted selection programs to improve the performance of milk and related traits in Turkey dairy cattle populations.

Research on the diacylglycerol acyltransferase 1 (DGAT1) K232A marker in cattle shows inconsistent results across regions, largely due to small sample sizes, limited genetic variation, and data restricted to few lactations, which complicates establishing a reliable genotype–phenotype correlation. This research aimed to determine the effect of the K232A polymorphism of the bovine DGAT1 gene on milk production and quality traits in dairy cattle. We used 1104 cattle, including 828 Holstein Friesian and 276 Jersey cows. The analysis utilized extensive data from six lactations of cows raised on four commercial dairy farms. We genotyped the population using the polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) technique and Sanger sequencing for verification. We then evaluated the 305 d and test-day milk yields as well as fat and protein yields and percentages. The number of inseminations per conception and calving ease were also assessed as reproduction indices. Genotype–phenotype associations were quantified using linear mixed models. The AA genotype was absent in Jersey cows, and the heterozygous genotype was predominant in both breeds. The K232A marker was significantly associated with test-day milk yield, fat, and protein content in Jersey cows. Further, it substantially affected the fat percentage of milk in Holstein Friesian cows (p<0.001). We found that the KK genotype is highly desirable for milk quality and especially fat content. This comprehensive assessment demonstrated that the KK genotype of the DGAT1 K232A polymorphism significantly influenced fat and protein contents in dairy cattle.

The synthesis of fatty acids plays a critical role in shaping milk production characteristics in dairy cattle. Thus, identifying effective haplotypes within the fatty acid metabolism pathway will provide novel and robust insights into the genetics of dairy cattle. This study aimed to comprehensively examine the individual and combined impacts of fundamental genes within the fatty acid metabolic process pathway in Jersey cows. A comprehensive phenotypic dataset was compiled, considering milk production traits, to summarize a cow's productivity across three lactations. Genotyping was conducted through PCR-RFLP and Sanger sequencing, while the association between genotype and phenotype was quantified using linear mixed models. Moderate biodiversity and abundant variation suitable for haplotype analysis were observed across all examined markers. The individual effects of the FABP3, LTF and ANXA9 genes significantly influenced both milk yield and milk fat production. Additionally, this study reveals novel two-way interactions between genes in the fatty acid metabolism pathway that directly affect milk fat properties. Notably, we identified that the GGAAGG haplotype in FABP3×LTF×ANXA9 interaction may be a robust genetic marker concerning both milk fat yield and percentage. Consequently, the genotype combinations highlighted in this study serve as novel and efficient markers for assessing the fat content in cow's milk.

The implementation of a swift and economical molecular genetic approach, ensuring both efficacy and cost-effectiveness and facilitating population certification, is of utmost significance for breeders and the conservation of Turkiye's native pigeon biodiversity. In this study, we aimed to examine the genetic structure of racing pigeons (Columba livia domestica) raised in Turkiye using a genetic marker panel consisting of eight short tandem repeat (STR) loci. For this purpose, DNA was isolated from the shed feathers of 216 pigeons. Genomic DNA was amplified using the multiplex allele-specific PCR and subsequent capillary electrophoresis with ABI PRISM 3130XL Genetic Analyzer. Next, PCR products were analyzed in the GeneMapper Software program (Applied Biosystems). For parent testing, paternity index (PI), combined paternity index (CPI), and cumulative probability of paternity (CPP) were calculated. Furthermore, population genetic diversity was evaluated using heterozygosity (He), polymorphism information content (PIC), and Hardy–Weinberg equilibrium (HWE) testing. Results revealed that the total number of alleles is 81 and the number of alleles per locus varies between 4 and 19. The similarity rate between parent and offspring was calculated as 99.99% and above. Since no pedigree information was given when the samples were analyzed, obtaining this similarity ratio demonstrates the reliability of the panel. He values range from 0.362 to 0.919, and the PIC values range from 0.295 to 0.909. Loci PG-1, PG-2, and PG-3 show significant genetic diversity, with moderate to high PIC values reflecting varied allele frequencies in the population. Consequently, the set of seven STR markers (+ one sex marker) can be applied to identify and confirm parentage on a regular basis, thereby facilitating efficient breeding programs and ensuring genetic diversity conservation. This panel enables efficient pedigree analysis and gender determination, optimizing cost-effectiveness. The methodology presented in this study is ideal for pedigree analysis and breed certification in the Turkish pigeon breeding industry. Consequently, we affirm that the study data carries considerable national importance.

The aim of this study was to identify the effect of calving year on milk yield and milk composition traits in Holstein and Jersey cattle raised in Marmara and the Black Sea Regions of Turkey, respectively. The data set consisted of 582 dairy cows, which were 306 Holstein raised and 276 Jersey cows calving from 2011 to 2013. In this study, animals were identified and selected to be genotyped for the DGAT1 gene based on farm records. Except for fat yield, the effect of calving year on test day milk yield (TDMY), 305-day milk yield (305 DMY), fat percentage, protein percentage and protein yield of Jersey cows were affected by calving season. The effect of calving year on TDMY, 305 DMY, fat percentage, fat yield, protein percentage and protein yield of Holstein cows were found to be statically significant. In conclusion, in 2011 to 2013, milk yield and its composition in both Holstein and Jersey cows were significantly related to calving years.