Milk yield records from 1 to 5 lactations of Iranian Holstein cows were analyzed using repeatability and a number of multivariate models that varied in additive genetic variance structure. A total of313,006 milk yield records were used. The records were obtained from 116,531 cows born between 2001 and 2005. The animals originated from 2,355 sires and 91,212 dams. A multivariate model with heter...

Applying a multiple trait random regression (MT-RR) in national level and for whole test day records of a country is a great advance in animal breeding context. Having reliable (co) variance components is a critical step in applying multiple traits genetic evaluation especially in developing countries. Genetic parameters of milk, fat and protein yields were estimated for Iranian Holstein dairy ...

This experiment was aimed to study the association between the DGAT1 K232A polymorphism and milk production traits and somatic cell score (SCS) in Iranian Holstein dairy cows. The records of 408 animals from five dairy herds were randomly identified and then genomic DNA was extracted from blood using the modified-salting method described by Miller. RFLP-PCR was performed to obtain all the polym...

Electrocardiography (ECG) may be used to recognize cardiac disorders. Levels of milk production may change the serum electrolytes which its imbalance has a role in cardiac arrhythmia. Fifty high yielding and fifty low yielding Holstein dairy cows were used in this study. Electrocardiography was recorded by base-apex lead and blood samples were collected from jugular vein for measurement of seru...

The objective of this study was to investigate the effect of birth weight (BW) on future milk production and reproductive performance in Iranian Holstein cattle. Records of Holstein cows between 1967 and 2010 were obtained from the Animal Breeding Center of Iran. Birth weights within each herd were grouped into five categories based on the standard normal distribution curves (z ≤-0.8416, -0.841...

Pure Holsteins (n = 380) were compared to Normande/Holstein crossbreds (n = 245), Montbeliarde/Holstein crossbreds (n = 494), and Scandinavian Red/Holstein crossbreds (n = 328) for 305-d milk, fat, and protein production during first lactation. Scandinavian Red was a mixture of Swedish Red and Norwegian Red. Cows were housed at 7 commercial dairies in California and calved from June 2002 to Jan...

Several functions were used to model fixed and random part of the lactation curve in Iranian primiparous Holstein cows using random regression analysis. Legendre polynomials of orders three and four as well as parametric lactation curve for the random part of the first lactation milk production were compared to find the best model. The models differed in fixed regression lactation curve part an...

Fibroblast growth factor 2 (FGF2) serves in the uterine endometrium during estrous presenting in the bovine mammary gland which is responsible to express interferon-T (IFNT), and is an important agent to encourage the continuation of pregnancy in the ruminants. Significant associations have been found between genes affected by IFNT and genes that are responsible for milk production traits. Seme...

This study was conducted to estimate the additive genetic components of calf mortality in the first month of age, calving difficulty, and birth weight in Holstein dairy cows in the central regions of Iran. The records comprised 61,200 calves born between 1990 and 2011 from 60 dairy herds. Different threshold-linear models in three groups of univariate, bivariate, and multivariate models were us...

The conformation traits of cows are heritable and linked with functionality and longevity. The dominant dairy breed in Europe is the Holstein. The objectives of this study were to evaluate exterior traits dependence on genotype of Lithuanian Black and White cows according to the degree of Holstein genes. For analysis, the conformation traits data of 53160 cows (in average of 2.7±0.01 lactation)...