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Animal Science Papers and Reports

Factors affecting genetic correlation estimates from dairy sires’ genetic evaluations to assess genotype-environment interaction

Hugo H. Montaldo
Departamento de Genética y Bioestadística, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria, 04510, D.F., Mexico
Abstract :
Effects of trait heritability (0.05 or 0.25), effective daughters number (30 to 500), sires number (10
to 500), and sire selection (selecting or not the top 50% sires), were evaluated based upon standard
error (SE) and bias of genetic correlations (
r
G
) between countries estimated from Calo’s method (
r
G
)
using simulated data. Calo’s method is based on correlations between sire’s predicted transmitting
abilities (PTA) in two countries adjusted for reliabilities. Unselected sire’s data analysis gave nearly
unbiased
r
G
in all cases, but selected sire’s data analysis gave underestimates. Bias was from -0.34 to
-0.05 for the 0.25 heritability trait (milk yield), and from -0.42 to -0.17 for the 0.05 heritability trait
(functional). Underestimation of
r
G
decreased with increased effective number of daughters (PTA’s
reliability), but was quite insensitive to number of sires. The SE of genetic correlations estimates
decreased with increased PTA’s reliability and sires number, and was higher for selected sires.
Approximately 50 sires with PTA’s reliabilities≥0.97 on each country are required to obtain accurate
(SE≤0.02) and unbiased (bias≤0.05|)
r
G
with Calo’s method using the best 50% selected sires. Many
genetic correlation estimates between countries, already published using the Calo’s method, may be
underestimates, particularly for low heritability traits, and with low number of effective daughters
in the importing country. Therefore, caution is required before interpreting the published
r
G
<1 as
evidence for genotype-environment interaction.
Keywords :
bias /genetic correlation / genotype-environment interaction / international evaluation of bulls

Date Deposited : 01 Apr 2015 15:57

Last Modified : 01 Apr 2015 15:57

Official URL: http://www.ighz.edu.pl/?p0=5&p1=34&o=7497

Volume 30, Number 3, - 2012

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