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Fit of different functions to the individual deviations in random regression test day models for milk yield in dairy cattle

Macciotta, Nicolò Pietro Paolo and Miglior, Filippo and Cappio Borlino, Aldo and Schaeffer, Lawrence R. (2007) Fit of different functions to the individual deviations in random regression test day models for milk yield in dairy cattle. Italian Journal of Animal Science, Vol. 6 (Suppl. 1), p. 153-155. eISSN 1828-051X. Article.

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Abstract

The shape of individual deviations of milk yield for dairy cattle from the fixed part of a random regression test day model (RRTDM) was investigated. Data were 53,217 TD records for milk yield of 6,229 first lactation Canadian Holsteins in Ontario. Data were fitted with a model that included the fixed effects of herd-testdate, DIM interval nested within age and season of calving. Residuals of the model were then fitted with the following functions: Ali and Schaeffer 5 parameter model, fourth-order Legendre Polynomials, and cubic spline with three, four or five knots. Result confirm the great variability of shape that can be found when individual lactation are modeled. Cubic splines gave better fitting pe4rformances although together with a marked tendency to yield aberrant estimates at the edge of the lactation trajectory.

Item Type:Article
ID Code:983
Status:Published
Refereed:Yes
Uncontrolled Keywords:Lactation curve modelling, andom regression models
Subjects:Area 07 - Scienze agrarie e veterinarie > AGR/17 Zootecnica generale e miglioramento genetico
Divisions:001 Università di Sassari > 01 Dipartimenti > Scienze zootecniche
Publisher:Avenue media on behalf of Scientific Association of Animal Production (ASPA)
eISSN:1828-051X
Publisher Policy:Depositato per gentile concessione dell'ASPA
Additional Information:Relazione presentata al 17. Congresso nazionale ASPA, Alghero, 29 maggio-1 giugno 2007.
Deposited On:18 Aug 2009 10:03

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