Leitner, G. 162 INTRODUCTION Economic pressure drives modern dairy farmers to exert continuous efforts to maximize profitability. This is achieved by constant improvement of genetic selection, nutrition, and herd management. Modern dairy farms are characterized by high levels of computerized data acquisition, which provides on-line information on cows' milk yield, milk composition and body weig...

First-lactation test-day milk, fat, and protein yields from New York, Wisconsin, and California herds from 1990 through 2000 were adjusted additively for age and lactation stage. A random regression model with third-order Legendre polynomials for permanent environmental and genetic effects was used. The model included a random effect with the same polynomial regressions for 2 yr of calvings wit...

Animals that are robust to environmental changes are desirable in the current dairy industry. Genetic differences in micro-environmental sensitivity can be studied through heterogeneity of residual variance between animals. However, residual variance between animals is usually assumed to be homogeneous in traditional genetic evaluations. The aim of this study was to investigate genetic heteroge...

Records from Dairy Records Management Systems in Raleigh were used to estimate effects of bovine somatotropin (bST) treatment and to predict breeding values for milk production traits. The data comprised 5245 test-day records of bST-treated cows and 126,223 test-day records of untreated cows in first lactation for milk, fat, and protein yields. Fixed effects of bST treatment were estimated from...

Objective- Locomotor disorders are prevalent health problems in dairy herds that negatively affect milk production, reproduction performance and animal welfare. The ultimate cost of locomotor disorders in dairy cattle is substantially greater than treatment costs alone. As limited information is available on incidence of feet and leg disorders in Iran, the objective of this study was to determi...

correlation between breeding value of crude milk (cm) and energy-corrected milk (ecm) was studied based on a total of 774,013 test day records belongs to 88,456 first-parity holsteins dairy cattle calving during 1997-2009 in 165 herds (from six provinces). genetic analysis of the traits was carried out by a fixed regression test day model. in the model, effects of herd, calving year, production...

the milk and milk fat production records of 28 holstein herds in khorasan razavi province were analyzed in this study. the records were based on 305 days of milking and were from the first to third milking periods and two times milking per day. the fixed effects of herd-year-season and age of dam at parturition as covariate were fitted in the models of analyses. the (co)variance components were...

A method to detect and to adjust or exclude abnormally low or high milk, fat, and protein yields on test-day (TD) was developed. Predicted TD yield is calculated based on preceding and subsequent (if available) TD yields. Observed TD yields that are < 60% or > 150% of predicted TD yield are defined as abnormal. Most abnormal yields are adjusted to this floor or ceiling, but some are excluded. Y...