Genetic evaluation of growth traits in Iranian Kordi Sheep using random regression model with homogeneous and heterogeneous residual variances
2017
The purpose of this study was estimation of genetic parameter using random
regression model (RRM) with various error variance in Iranian Kordi sheep.
The data (consisting of 7875 weight records from birth to 360 days of age)
were collected during the period 2000 to 2013 from the rearing and breeding
station of Kordi sheep in Shirvan, Iran. The independent variables were
Legendre polynomials (LP) of age at weighing and orders of fit from 2 to 5
were considered. Analyses were carried out fitting sets of random regression
coefficients due to direct additive genetic, direct and maternal permanent
environmental effects, with heterogeneous and homogeneous error variances.
To compare the model were used different criteria such as LogL, AIC, BIC and
LRT. The best fitting RRM among homogeneous error variance was the model
with a LP of fourth order for fixed effect, fourth order for direct additive
genetic and fifth order for direct and maternal permanent environmental
effects (model 4455). Among the models with heterogeneous error variances
different, model 7 (Heterogeneous error variances of 72 various classes),
was selected as the best model. The variances increased along the trajectory
from 3.75 to 12.81, 4.43 to 30.28 and 1.49 to 8.49; 0.25 to 27.94, 0.03 to
12.32 and 0.15 to 22.66 for direct additive genetic, direct and maternal
permanent environmental effect by homogeneous and heterogeneous error
variances, respectively. The direct heritability ranged from 0.15 to 0.41
and 0.11 to 0.56 by homogeneous and heterogeneous error variances,
respectively. Genetic correlation between adjacent test days was more than
between distant test days. This research has demonstrated the possibility of
application of RRM with heterogeneous error variance for genetic evaluation
of Iranian Kordi Sheep.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
2
Citations
NaN
KQI