BACKGROUND The milk yield can be affected by the frequency of milking per day, in dairy cows. Previous studies have shown that the milk yield is increased by 6-25 % per lactation when the milking frequency is increased from 2 to 3 times per day while the somatic cell count is decreased. To investigate the effect of milking frequency (3X vs. 4X) on milk yield and it's genetic parameters in the f...

This experiment was conducted to determine the association between several risk factors which may affect culling of the Iranian Holstein cows. The data consisted of 329,772 lactation records collected by the Animal Breeding Center of Iran (2003 to 2012).The logistic regression was applied to investigate the associations between the response variable, the risk of culling, and predictor variables...

ABSTRACT: Transmissible spongiform encephalopathies are neurodegenerative diseases that affect several mammalian species. Bovine spongiform encephalopathy (BSE) is among the mentioned diseases in cattle caused by abnormally fold prion proteins. Polymorphisms of the prion protein gene (PRNP) have been shown to be major determinations for the susceptibility to transmitted perion diseases in human...

OBJECTIVE During the last decade, genetic evaluation of dairy cows using longitudinal data (test day milk yield or 305- day milk yield) using random regression method has been officially adopted in several countries. The objectives of this study were to estimate covariance functions for genetic and permanent environmental effects and to obtain genetic parameters of 305-day milk yield over seven...

The aim of this study was to investigate effects of DGAT1, OPN and PPARGC1A candidate genes on milk production traits in Iranian Holstein cattle. Several papers have studied single nucleotide polymorphisms (SNPs) and their association with economic traits in dairy cows, but the combined effect of these genes has not been examined in Iranian Holstein cattle population. Blood samples were collect...

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 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)...

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 purpose of this study was to investigate the effect of maternal inbreeding on incidence of twinning,dystocia and stillbirth in Holstein cows of Iran. Calving records from March 2000 to April 2009 comprisingof 365,021 calvings on 153,802 cows from 86 dairy herds were used. The mean level of inbreeding was0.7%, less than 37% of all animals were inbred, and a small proportion (3.45%) of inbree...

This investigation was conducted to identify polymorphism of the leptin gene in Holstein cows, Mazandarani native cattle and buffaloes by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP). The frequencies of A and B alleles were 0.4 and 0. 6 in Holstein cows, 0.56 and 0.44 in Mazandarani native cattle, 0.61 and 0.35 in buffaloes, respectively. The heterozygote genoty...