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    A comprehensive analysis of the effects of DGAT1 K232A polymorphism on milk production and fertility traits in Holstein Friesian and Jersey cows reared in Turkiye
    (Copernicus Gesellschaft Mbh, 2024) Ardicli, Sena; Cobanoglu, Ozden; Kul, Ertugrul; Abaci, Samet Hasan; Gurcan, Eser Kemal; Cankaya, Soner
    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.
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    Determination of the association of GHR/Alul gene polymorphisms with milk yield traits in Holstein and Jersey cattle raised in Turkey
    (Copernicus Gesellschaft Mbh, 2021) Çobanoglu, Özden; Kul, Ertuğrul; Gürcan, Eser Kemal; Abaci, Samet Hasan; Çankaya, Soner
    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.
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    Effects of lactation month and season on test-day milk yield and milk components in Holstein cows
    (Agricultural Research Communication Centre, 2017) Çobanoglu, Özden; Gürcan, Eser Kemal; Çankaya, Soner; Kul, Ertuğrul; Abaci, Samet Hasan; Ülker, Mehmet
    This study aims to determine the correlations between the test-day milk yield (TDMY) and the fat and protein content as well as the fat and protein yields in Holstein dairy cows and to investigate the effects of lactation period and sampling season on these parameters. The study material consists of 1.380 records of a total of 151 head of Holstein dairy cows raised on a private farm in Samsun province. In the study, the mean TDMY, fat content, protein content, fat yield and protein yield were recorded as 20.6 +/- 5.10 kg, 3.97 +/- 0.734%, 3.23 +/- 0.276%, 0.81 +/- 0.210 kg and 0.66 +/- 0.160 kg, respectively. The effects of lactation period and sampling season on the TDMY, fat content, protein content, fat yield and protein yield were found statistically significant (P<0.01). Statistically significant negative correlations were determined between the TDMY and the fat and protein content, but positive and statistically significant (P<0.01) correlations between the TDMY and the fat and protein yields. In conclusion, it might be stated that the effects of lactation period and sampling season should also be taken into account to improve milk yield and milk components.
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    Genetic Polymorphism of STAT1 and STAT5A Genes in Holstein, Jersey, and Indigenous Cattle Breeds in Turkey
    (Kafkas Univ, Veteriner Fakultesi Dergisi, 2020) Çobanoglu, Özden; Kul, Ertuğrul; Abaci, Samet Hasan; Gürcan, Eser Kemal; Çankaya, Soner
    This study aimed to determine genetic polymorphism in STAT1 and STAT5A genes for dairy cattle and some native cattle breeds in Turkey. 283 Jersey and a total of 472 Holstein cows from two different herds and 93 Grey Steppe, 85 Anatolian Black Cattle, and 66 East Anatolian Red cattle were used in this research. Generally, C allele gene frequency was higher than T allele for STAT1 in all breeds whereas C allele gene frequency was detected higher than G allele for STAT5A in Jersey and East Anatolian Red. On the other hand, G allele gene frequency was higher than C allele in Holstein, Grey Steppe, and Anatolian Black Cattle breeds. The expected deviations from the Hardy-Weinberg Equilibrium were significant only for Jersey breeds for STAT1 gene. Meanwhile, the expected deviation from equilibrium was also significantly different for Holstein in Black Sea Region (BSR), Anatolian Black Cattle and Grey Steppe for the STAT5A gene. FIS values were determined to STAT1 gene as negative for all breeds except for Holstein in Marmara Region (MR). Similarly, this value was determined to STAT5A gene as positive for all breeds except for Holstein in BSR. The genetic distances for two loci were calculated between 0.0029 and 0.1599 among all populations. Depending on the cluster analysis, Holstein in BSR and MR, Anatolian Black Cattle, East Anatolian Red were closely clustered to each other, while Grey Steppe and Jersey were located in completely different clusters. As a conclusion, based on the detected genetic diversity in STAT1 and STAT5A genes, it is possible to make a genetic improvement among bovine breeds raised in Turkey.
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    Influence of Some Environmental Factors on Milk Yield and Milk Components Traits in Jersey Cows
    (Parlar Scientific Publications (P S P), 2019) Çobanoglu, Özden; Kul, Ertuğrul; Gürcan, Eser Kemal; Çankaya, Soner; Abaci, Samet Hasan; Ülker, Mehmet
    This study was conducted to assess the effects of stage of lactation, parity and sampling season on milk yield and milk components in Jersey cows in Karakoy State Farm, Turkey. The data set consisted of 2657 milk records of 204 Jersey cows collected from September 2011 to December 2013. For this purpose, test day milk yield (TDMY) records and milk samples were taken once a month for 10-month period after parturition. The effect of stage of lactation, parity and sampling season on TDMY, fat percentage, protein percentage, fat yield and protein yield were found statistically significant (P<0.01). TDMY were correlated with fat percentage (-0.235) and protein percentage negatively (-0.254) but with fat yield (0.755) and protein yield positively (0.950) (P<0.01). In conclusion, these results suggest animal breeders that the effects of lactation stage, parity and sampling season may be taken into account in husbandry management to improve the milk yield and milk quality in Jersey cows.