Related Experiment Video
Updated: Jul 13, 2026
04:56
An Efficient Single-Person Technique for Milk Sampling from Laboratory Mice
Published on: March 28, 2025
Modeling extended lactations of Holsteins.
C M B Dematawewa1, R E Pearson, P M Vanraden
1Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24060, USA. mahinda@vt.edu
Journal of Dairy Science
|July 20, 2007
Summary
This study compared nine models for predicting US Holstein milk production over 305-day and extended 999-day lactations. Smaller models like Rook (RK), Dijkstra (DJ), and Wood (WD) are recommended for extended lactations due to their balance of accuracy and computational efficiency.
Area of Science:
- Animal Science
- Dairy Production
- Quantitative Genetics
Background:
- A majority of US Holstein cows have lactations exceeding 305 days, necessitating models for extended lactation prediction.
- Accurate modeling of lactation curves is crucial for dairy herd management and genetic evaluations.
Purpose of the Study:
- To evaluate and compare nine empirical and mechanistic models for their suitability in modeling both standard (305-day) and extended (999-day) lactations in US Holsteins.
- To identify the most accurate and computationally efficient models for predicting daily milk yield and composition over different lactation lengths and parities.
Main Methods:
- Utilized a large dataset of 4,266,597 test-day yields from 427,657 US Holstein lactation records.
- Fitted nine distinct models (Wood, Wilmink, Rook, Monophasic, Diphasic, LPM, Dijkstra, Pollott, New-Multiphasic) to 305-day and 999-day lactations across different parities.
- Assessed model performance using residual analysis, prediction error, mean square error, and Bayesian information criteria.
Main Results:
- All tested models provided a significant fit for both 305-day and 999-day lactations.
- Empirical models like Rook (RK), Dijkstra (DJ), and Wood (WD), along with mechanistic models Pollott (POL) and New-Multiphasic (MULT), showed good predictive accuracy for extended lactations (+/- 3 kg range).
- While POL and MULT models had the lowest error metrics, they suffered from convergence issues and unreliable parameter estimates; RK, DJ, and WD offered a better balance of accuracy and practicality.
Conclusions:
- For modeling extended lactations in US Holsteins, smaller, established models such as Rook (RK), Dijkstra (DJ), and Wood (WD) are recommended for their balance of predictive accuracy and computational efficiency.
- These recommended models also adequately describe fat and protein yields across different lactation lengths and parities.
- Mechanistic models may be considered if detailed insights into the extended lactation curve dynamics are specifically required.
