Title:	Estimation of genetic parameters for test-day milk yield in Girolando cows using a random regression model.
Authors:	SANTOS, E. P. B. FELTES, G. L. NEGRI, R. COBUCI, J. A. SILVA, M. V. G. B.
Affiliation:	Pós-graduando, Universidade Estadual de Santa Cruz; Pós-graduando, Universidade Federal do Rio Grande do Sul; Universidade Federal do Rio Grande do Sul; Universidade Federal do Rio Grande do Sul; MARCOS VINICIUS GUALBERTO B SILVA, CNPGL.
Date Issued:	2021
Citation:	Arquivo Brasileiro de Medicina Veterinária e Zootecnia, v. 73, n. 1, p. 18-24, 2021.
Description:	The objective of this study was to estimate the components of variance and genetic parameters of test-day milk yield in first lactation Girolando cows, using a random regression model. A total of 126,892 test-day milk yield (TDMY) records of 15,351 first-parity Holstein, Gyr, and Girolando breed cows were used, obtained from the Associação Brasileira dos Criadores de Girolando. To estimate the components of (co) variance, the additive genetic functions and permanent environmental covariance were estimated by random regression in three functions: Wilmink, Legendre Polynomials (third order) and Linear spline Polynomials (three knots). The Legendre polynomial function showed better fit quality. The genetic and permanent environment variances for TDMY ranged from 2.67 to 5.14 and from 9.31 to 12.04, respectively. Heritability estimates gradually increased from the beginning (0.13) to mid-lactation (0.19). The genetic correlations between the days of the control ranged from 0.37 to 1.00. The correlations of permanent environment followed the same trend as genetic correlations. The use of Legendre polynomials via random regression model can be considered as a good tool for estimating genetic parameters for test-day milk yield records.
Thesagro:	Gado Leiteiro Bovino Variação Genética Parâmetro Genético
Keywords:	Correlação genética Função de Wilmink Herdabilidade Polinômios de Legendre Polinômios splines lineares
DOI:	http://dx.doi.org/10.1590/1678-4162-12071
Type of Material:	Artigo de periódico
Access:	openAccess
Appears in Collections:	Artigo em periódico indexado (CNPGL)