Title:	Genetic parameters for milk yield and lactation persistency using random regression models in Girolando cattle.
Authors:	CANAZA-CAYO, A. W. LOPES, P. S. SILVA, M. V. G. B. TORRES, R. de A. MARTINS, M. F. ARBEX, W. A. COBUCI, J. A.
Affiliation:	Ali William Canaza-Cayo, Universidad Nacional del Altiplano, Peru; Paulo Sávio Lopes, UFV; MARCOS VINICIUS GUALBERTO B SILVA, CNPGL; Robledo de Almeida Torres, UFV; MARTA FONSECA MARTINS, CNPGL; WAGNER ANTONIO ARBEX, CNPGL; Jaime Araujo Cobuci, UFRGS.
Date Issued:	2015
Citation:	Asian-Australasian Journal of Animal Sciences, v. 28, n. 10, p. 1407-1418, 2015.
Description:	A total of 32,817 test-day milk yield (TDMY) records of the first lactation of 4,056 Girolando cows daughters of 276 sires, collected from 118 herds between 2000 and 2011 were utilized to estimate the genetic parameters for TDMY via random regression models (RRM) using Legendre's polynomial functions whose orders varied from 3 to 5. In addition, nine measures of persistency in milk yield (PSi ) and the genetic trend of 305-day milk yield (305MY) were evaluated. The fit quality criteria used indicated RRM employing the Legendre's polynomial of orders 3 and 5 for fitting the genetic additive and permanent environment effects, respectively, as the best model. The heritability and genetic correlation for TDMY throughout the lactation, obtained with the best model, varied from 0.18 to 0.23 and from –0.03 to 1.00, respectively. The heritability and genetic correlation for persistency and 305MY varied from 0.10 to 0.33 and from –0.98 to 1.00, respectively. The use of PS7 would be the most suitable option for the evaluation of Girolando cattle. The estimated breeding values for 305MY of sires and cows showed significant and positive genetic trends. Thus, the use of selection indices would be indicated in the genetic evaluation of Girolando cattle for both traits. (Key Words: Genetic Trend, Genetic Parameters, Lactation Persistency, Legendre's Polynomials, Random Regression Model, Cattle)
NAL Thesaurus:	genetic trend cattle
Keywords:	Genetic Parameters Lactation Persistency Legendre's Polynomials Random Regression Model
Type of Material:	Artigo de periódico
Access:	openAccess
Appears in Collections:	Artigo em periódico indexado (CNPGL)