Cluster analysis of breeding values for milk yield and lactation persistency in Guzerá cattle

• Main Author: Cruz,Diego Augusto Campos da
• Publication Date: 2016
• Other Authors: Savegnago,Rodrigo Pelicioni, Santana,Annaíza Braga Bignardi, Peixoto,Maria Gabriela Campolina Diniz, Bruneli,Frank Angelo Tomita, Faro,Lenira El
• Format: Article
• Language: eng
• Source: Ciência Rural
• Download full: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-84782016000701281
• topic: breeding values; lactation curve; random regression

ABSTRACT: The aim of this study was to explore the pattern of genetic lactation curves of Guzerá cattle using cluster analysis. Test-day milk yields of 5,274 first-lactation Guzerá cows were recorded in a progeny test. A total of 34,193 monthly records were analyzed with a random regression animal model using Legendre polynomials to fit additive genetic and permanent environmental random effects and mean trends. Hierarchical and non-hierarchical cluster analyses were performed based on the EBVs for monthly test-day milk yield, peak yield, lactation persistency, and partial cumulative and 305-day yields. The heritability estimates for test-day milk yields ranged from 0.24 to 0.52. Cluster analysis identified animals in the population that belong to different groups according to milk production level and lactation persistency.