A functional candidate gene approach was used to search for genes affecting milk production traits in Holstein dairy cattle. Signal transducer and activator of transcription 1 (STAT1) was chosen because of its involvement in the development of the mammary gland. Using the pooled genomic DNA sequencing approach, we identified a single nucleotide polymorphism. Genomic DNA was extracted from 1,292 sons obtained from the Cooperative Dairy DNA Repository and from 715 blood samples of daughters of 12 bulls obtained from the University of Wisconsin resource population. Daughter yield deviation data for the sons and yield deviation for the daughters were obtained for milk production traits from the USDA Animal Improvement Programs Laboratory. For the Repository population, allele C was associated with significant increases in milk fat and protein percentages. For the University of Wisconsin population, genotypes CC and CT were associated with significant increases in milk, fat, and protein yields. Results from this study are consistent with previous studies on the role of STAT1 in regulating the transcription of genes involved in milk protein synthesis and fat metabolism.

The objective of this study was to identify twinning rate quantitative trait loci (QTL) by typing pooled samples in a preliminary screening followed by interval mapping to test QTL effects. Four elite North American Holstein half-sib sire families with high twinning rate predicted transmitting abilities (PTA) were used in this study. Chromosomes 5, 7, 19 and 23 were not genotyped as these chromosomes were scanned for QTL in these families in a previous study. DNA was extracted from phenotypically extreme sons in each sire family. Two pools were prepared from sons of sires in each phenotypic tail, two each for high and low PTA levels for twinning rates. Each pool contained DNA from 4 to 15% of all sons of the sire depending on family. A total of 268 fluorescently labelled microsatellite markers were tested for heterozygosity in sires. About 135--170 informative markers per family were genotyped using pooled DNA samples. Based on the preliminary evidence for potential twinning rate QTL from pooled typing, interval mapping was performed subsequently on 12 chromosomal regions by family combinations. Evidence of QTL for twinning rate was found in one family on BTA 21 and 29 at a chromosome-wide P<0.05 and on BTA 8, 10 and 14 with a chromosome-wide P<0.01.

Twinning in cattle is a complex trait that is associated with economic loss and health issues such as abortion, dystocia, and reduced calf survival. Twinning-rate QTL have been detected previously on BTA5 in the North American Holstein and Norwegian dairy cattle populations and in a USDA herd selected for high twinning rate. In previous work with the North American Holstein population, the strongest evidence for a QTL was obtained from analysis of an extended, multiple-generation family. Using additional animals, an increased density of SNP marker association tests, and a combined linkage and linkage disequilibrium mapping method, we refined the position of this QTL in the North American Holstein population. Two sets of twinning-rate predicted transmitting abilities estimated during 2 different time periods in the North American dairy cattle population were used to provide validation of results. A total of 106 SNP and 3 microsatellites were used to scan the genomic region between 5 and 80 Mb on BTA5. Combined linkage-linkage disequilibrium analysis identified significant evidence for QTL within the 25- to 35-Mb and 64- to 70-Mb regions of BTA5. The IGF-1 gene (IGF1) was examined as a positional candidate gene and an SNP in intron 2 of IGF1 was significantly associated with twinning rate by using both data sets (P = 0.003 and P = 1.05 x 10(-6)). Replication of this association in other cattle populations will be required to examine the extent of linkage disequilibrium with the underlying quantitative trait nucleotide across breeds.

ABSTRACT:In Turkey most farmers keep 1-2 buffaloes for family consumption and this system is very widespread in villages while farms with around 100 heads are located near to the big cities. These two most common housing systems were used to contribute to the somatic characterization of Anatolian buffalo in the context of a wide typification programme of this buffalo aimed to improve its productive and reproductive potentiality in agreement with a sustainable development. 76 males and 127 females of the Istanbul district and 32 males and 70 females raised in Danamandra vıllage of Silivri district were measured. On each buffalo, withers height, rump height, body length, chest depth and chest width were determined. The results showed a significant difference between males and females starting from 12 months in buffaloes of Danamandra village and from 3 years of age in animals of Istanbul district.

Abstract:The main purpose of this study was to detect an association of cytoplasmic signal transducers and activators of transcription-1 (STAT1) with milk production traits in 472 Holstein and 283 Jersey cattle breeds of Turkey. This gene, located on chromosome 2, was chosen due to its role on development of mammary gland. A polymorphism of selected 314 bp allele fragment was detected by the restriction fragment length polymorphism analysis of polymerase chain reaction-amplified fragments (PCR-RFLP) method and also confirmed by DNA sequencing. The association tests were conducted between STAT1 genotypes and some economically important dairy traits. The genotypes for C/T as a single nucleotide polymorphism (SNP) were identified at interval 60 cM to 63 cM. The effects of STAT1 gene on milk production traits were not significant in Holstein cows, although animals with CT genotypes showed fairly close to significant value for the corrected 305 d milk yield. However, Jersey cows with TT genotype were 2.07 kg higher for test-day milk yield (P < 0.05), 0.13 kg for fat yield (P < 0.01) and 0.07 kg for protein yield (P < 0.05) compared with animals having CC and CT genotypes. Definitely, the further research should be conducted to search this gene intensively with larger samples to identify polymorphism and any association between the economically important traits and genotypic class in Holstein cows. Finally, based on the findings, it was concluded that STAT1 gene might be used as a potential candidate gene to improve milk yield and milk fat and protein contents in dairy cows breeding programs.

The aim of this study was to estimate the genetic parameters and environmental factors for test day milk yield (TDMY), lactation milk yield (LMY), 305-day milk yield (305-DMY), milk fat percentage (FP) and milk protein percentage (PP) of Jersey cows raised on Karaköy Agricultural State Farm in Samsun province of Turkey. The data were obtained from 279 milk yield records of 170 heads cows calved from 2011 to 2013 years. Parity, calving season and calving year were considered as fixed effects. Heritability, additive genetic variance and phenotypic variance were estimated by multiple trait derivative free restricted maximum likelihood (MTDFREML) with the animal model. Variance analysis results showed that except for FP, the effects of parity and calving year on TDMY, LMY, 305-DMY and PP were significantly important (P<0.05). However, calving season did not affect TDMY, LMY, 305-DMY, FP and PP (P>0.05). Heritability estimates for TDMY, LMY, 305-DMY, FP and PP were 0.38, 0.30, 0.28, 0.19, and 0.36, respectively. Repeatability for TDMY, LMY, 305-DMY, FP and PP were ranged from 0.35 to 0.45. The results indicate that these traits can be used as a selection criteria in genetic improvement of Jersey cattle this herd.

In this study, it is aimed to determine GHR gene polymorphism in dairy cattle and some native cattle breeds raised in different regions of Turkey. The study was carried out by 468 Holstein, 280 Jersey, 93 Grey Steppe, 86 Native Black, and 64 East Anatolian Red animals. The FIS values of the populations for the GHR gene were detected negatively except for Grey Steppe and Native Black. FIS value was found 14% and negative with reference to heterozygote genotype was higher than homozygote genotypes in overall population. The expected deviations from the Hardy-Weinberg Equilibrium in terms of the GHR locus were found significant in these five different breeds except for Native Black. The genetic distance values among the populations were calculated between 0.0004 and 0.1881. Based on the cluster analysis, Holstein and East Anatolian Red were located in close cluster; however Jersey, Native Black and Grey Steppe were grouped as in different clusters. As a result, the genetic variation in five different cattle breeds grown in our country in terms of GHR gene has been determined by genetic clustering analysis. Therefore, it can be said that it is possible to increase the level of the yield traits in these breeds based on a genetic progression.

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