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Development of an Individual-Tree Basal Area Increment Model using a Linear Mixed-Effects Approach
Published on: July 3, 2020
Estimating digestible methionine requirements for laying hens using multivariate nonlinear mixed effect models.
A B Strathe1, A Lemme, J K Htoo
1Department of Animal Science, University of California, Davis, CA, USA. abstrathe@ucdavis.edu
Poultry Science
|June 16, 2011
Summary
A new framework for analyzing farm animal dose-response data was developed. This analysis of digestible methionine requirements in laying hens found the requirement for egg mass is 356 mg/d, and for feed utilization is 390 mg/d.
Area of Science:
- Animal Nutrition
- Statistical Modeling
- Meta-Analysis
Background:
- Accurate determination of nutrient requirements is crucial for optimizing animal production and feed efficiency.
- Previous studies on methionine requirements in laying hens often analyzed responses separately, potentially overlooking interdependencies.
- A unified statistical framework is needed to simultaneously analyze multiple dose-response outcomes in farm animals.
Purpose of the Study:
- To develop and apply a unified framework for analyzing dose-response data in farm animals.
- To conduct a meta-analysis of digestible methionine requirements for laying hens, modeling egg mass and feed utilization concurrently.
- To identify the optimal dose-response function and investigate the influence of covariates on methionine requirements.
Main Methods:
- Constructed a database of methionine dose-response data from 23 trials across 15 publications.
- Employed a multivariate nonlinear mixed effects model to simultaneously analyze egg mass and feed utilization.
- Compared linear broken-line, quadratic plateau, and monomolecular functions; utilized the quadratic plateau model for biological inference.
Main Results:
- The multivariate model, accounting for correlated random effects and errors, provided a superior fit compared to separate analyses.
- Laying hen body weight significantly influenced asymptotic responses, explaining substantial between-study variability.
- The estimated digestible methionine requirement for maximizing egg mass was 356 mg/d, while for maximizing feed utilization it was 390 mg/d.
Conclusions:
- A unified framework for simultaneous analysis of multiple dose-response outcomes improves data analysis in animal nutrition.
- The biological requirement for digestible methionine in laying hens is at least 356 mg/d for optimal egg mass production.
- Simultaneous analysis is recommended when multiple responses are measured in dose-response studies to accurately establish nutrient requirements.
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