Persistence in milk, fat and protein production of primiparous Holstein cows by random regression models

Evaluation of Test Day Milk Yield in Iranian Primiparous Holstein Using Different Random Regression Models

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...

Effects of daily exogenous oxytocin injections on milk production and fat yield in holstein cows

Evaluation of Various Approaches in Prediction of Daily and Lactation Yields of Milk and Fat Using Statistical Models in Iranian Primiparous Holstein Dairy Cows

In this research, 272977 test day records collected from 659 herds during years 2001 to 2011 by the Iranian animal breeding center were used. In the first section the ability of different models to predict daily milk yield from alternative milk recording was tested. The result showed that a complex model including noon milking time plus the effect of lactation curve of Ali and Schaeffer functio...

Analysis of Test Day Milk Yield by Random Regression Models and Evaluation of Persistency in Iranian Dairy Cows

Variace / covariance components of 227118 first lactaiom test-day milk yield records belonged to 31258 Iranian Holstein cows were estimated using nine random regression models. Afterwards, different measures of persistency based on estimation breeding value were evaluated. Three functions were used to adjust fixed lactation curve: Ali and Schaeffer (AS), quadratic (LE3) and cubic (LE4) order of...

Random regression models using different functions to model test-day milk yield of Brazilian Holstein cows.

We analyzed 152,145 test-day records from 7317 first lactations of Holstein cows recorded from 1995 to 2003. Our objective was to model variations in test-day milk yield during the first lactation of Holstein cows by random regression model (RRM), using various functions in order to obtain adequate and parsimonious models for the estimation of genetic parameters. Test-day milk yields were...