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 data from the newly available 50 K SNP chip was used for tagging the genome-wide footprints of positive selection in Holstein-Friesian cattle. For this purpose, we employed the recently described Extended Haplotype Homozygosity test, which detects selection by measuring the characteristics of haplotypes within a single population. To assess formally the significance of these results, we com...

The objective of the study was to evaluate the uterine histopathological changes in Holstein dairy cows, within the range of 90-145 day in milk, with or without clinical history of reproduction system disorders. Lactating Holstein cows (n =133) with (n=92, 69.17%) or without (n= 41, 30.82%) recorded clinical signs of reproduction diseases were examined for uterine histopathological lesions. The...

The objective of this study was to evaluate the effect of ruminally protected amino acids (RPAAs) and ruminally protected fat (RPF) supplementation on ruminal fermentation characteristics (in vitro) and milk yield and milk composition (in vivo). Fourteen mid-lactating Holstein dairy cows (mean weight 653±62.59 kg) were divided into two groups according to mean milk yield and number of days of p...

Utilizing pasture-based systems may increase cow comfort during late gestation and calving as it lacks the constraints of confinement housing. The objective of this study was to quantify lying behavior and activity of Holstein dairy cows housed on pasture during the 6 d before calving. Sixteen Holstein dairy cows were moved to pasture 3 weeks before their projected calving date. Data loggers we...

A survey was conducted to quantify incidence of Beef Quality Assurance (BQA)-related defects in market beef and dairy cows and bulls selling at auction during 2 seasons in 2008. Twenty-three BQA-related traits were evaluated by 9 trained personnel during sales at 10 livestock auction markets in Idaho (n = 5; beef and dairy), California, (n = 4; dairy only), and Utah (n = 1; beef and dairy). Ove...

Objective-To assess the effect of lameness on culling of dairy cows in Tehran province. Design- Historical cohort study. Study population and procedures- 7067 first- and second-parity Holstein dairy cows that calved from March, 21 2007 to March, 20 2008 were until next calving or culling. Logistic regression was conducted data. Results-The overall lactational culling rate for eligible cows i...

this study utilized daily records of 2000 egyptian holstein dairy cows. the productive, reproductive and economic data during a whole lactation season were recorded for healthy and mastitis cows. two risk factors for mastitis were included, parity and season of calving. mastitis cows had significant (p

The artificial insemination (AI) industry in the United States has gone through many consolidations, mergers, and acquisitions over the past 25 yr. There are 5 major AI companies in the United States today: 3 large cooperatives, 1 private company, and 1 public company. The latter 2 have majority ownership outside of the United States. The AI industry in the United States progeny-tests more than...

this study was carried out in the winter of the year 2007 in a dairy herd at the vicinity of tehran (eslamshahr). measurements were performed on 18 holstein cows during first-lactation. five holstein dairy cattle were randomly selected and clinically studied, too. length of the claw’s dorsal flexure was measured with a ruler and also the hooves trimmed in the toe vertically for measuring of the...