Strategies for estimating the parameters needed for different test-day models

I. Misztal, T. Strabel, J. Jamrozik, E.A. Mäntysaari, T.H.E. Meuwissen

    Research output: Contribution to journalArticleAcademicpeer-review

    72 Citations (Scopus)


    Currently, most analyses of parameters in test-day models involve two types of models: random regression, where various functions describe variability of (co)variances with regard to days in milk, and multiple traits, where observations in adjacent days in milk are treated as one trait. The methodologies used for estimation of parameters included Bayesian via Gibbs sampling, and REML in the form of derivative-free, expectation-mazimization, or average-information algorithms. The first method is simpler and uses less memory but may need many rounds to produce posterior samples. In REML, however, the stopping point is well established. Because of computing limitations, the largest estimations of parameters were on fewer than 20,000 animals. The magnitude and pattern of heritabilities varied widely, which could be caused by simplifications in the model, over-parameterization, small sample size, and unrepresentative samples. Patterns of heritability differ among random regression and multiple-trait models. Accurate parameters for large multi-trait random regression models may be difficult to obtain at the present time. Parameters that are sufficiently accurate in practice may be obtained outside the complete prediction model by a constructive approach, where parameters averaged over the lactation would be combined with several typical curves for (co)variances for days in milk. Obtained parameters could be used for any model, and could also aid in comparison of models.
    Original languageEnglish
    Pages (from-to)1125-1134
    JournalJournal of Dairy Science
    Issue number5
    Publication statusPublished - 2000

    Fingerprint Dive into the research topics of 'Strategies for estimating the parameters needed for different test-day models'. Together they form a unique fingerprint.

  • Cite this

    Misztal, I., Strabel, T., Jamrozik, J., Mäntysaari, E. A., & Meuwissen, T. H. E. (2000). Strategies for estimating the parameters needed for different test-day models. Journal of Dairy Science, 83(5), 1125-1134.