A national US survey collected data on herd milk production and management of Holstein herds. Step-wise selection identified management practices that were related to herd milk production using only operations that calculated herd milk production as well as using data from all operations. Results were similar. Milk production was highest in the West. Operations with < 100 dairy cows had lower p...

The objectives of this study were to determine the effects of parity on milk production, body condition change, periparturient health, and culling in Korean dairy herds. The data utilized included; milk yield, body condition score, cow parity, calving condition, periparturient disorders, culling, and reproductive status, which were recorded from 1290 calvings in eight dairy herds. The mean milk...

The objectives of the present study were to evaluate colostrum quality in Norwegian dairy cows based on IgG content, and to identify associations between possible risk factors and low colostral IgG. A longitudinal cross-sectional survey on calf health in Norway was performed between June 2004 and December 2006. The participating dairy herds were randomly selected among herds registered in the N...

The objectives of this research were to characterize dry period lengths for US Jerseys, determine the effects of days dry (DD) on subsequent lactation actual milk, fat, and protein yields, fat and protein percentages, somatic cell score (SCS), and days open (DO), and to determine the dry period length that maximizes yield across lactations. Field data, collected through the Dairy Herd Improveme...

background: mastitis is an important health disorder in dairy herds which affects milk production, animal reproduction and production. objectives: the aim of this study was to estimate the cumulative incidence of mastitis in dairy herds in tehran province.  methods: from 679 dairy herds in tehran province that have more than 50 animals, 32 dairy herds were selected randomly and animals that had...

The objective of this study was to estimate genetic correlations between calving difficulty score and carcass traits in Charolais and Hereford cattle, treating first and later parity calvings as different traits. Genetic correlations between birth weight and carcass traits were also estimated. Field data on 59,182 Charolais and 27,051 Hereford calvings, and carcass traits of 5,260 Charolais and...

introduction secondary sex ratio (ssr) is the proportion of males to females at birth. it has been shown in many different mammalian species, many factors are associated with ssr. changes in secondary sex ratio in dairy cows is considered economically important and the ability to change it could affect the revenues and profitability of a dairy farm. thus, sperm or embryo sexing techniques in re...

Successful calving, healthy metabolic functions postpartum and good milk performance in lactation depend highly on the transition period (three weeks before and after calving) of dairy cows where they should be able to manage energy intake and overcome negative energy balance. Subclinical ketosis is one of the metabolic diseases associated with negative energy balance during the transition peri...

The objective of this study was to quantify the phenotypic and genetic risk factors associated with multiple ovulations and twin births in cattle. Prevalence and cow- and herd-level risk factors associated with ovulation rate were determined using 40,617 ultrasonographic records of the reproductive tract from 27,907 dairy and beef cows from 738 commercial herds. Prevalence of twin births was es...

If genetic evaluations are calculated with a single-trait repeatability model, evaluation changes may be attributed in part to bulls that have daughters that deviate considerably from the typical response to aging. Differences in maturity rate of bull daughters were examined to determine whether they influence change in bull evaluations. Standardized milk records for Holsteins that first calved...