EI-Arian, M. (2006). PARAMETER ESTIMATES FOR DIRECT AND MATERNAL GENETIC EFFECTS FOR MILK .YIELD TRAITS IN A FRIESIAN CATTLE HERD IN EGYPT. Journal of Animal and Poultry Production, 31(5), 2663-2669. doi: 10.21608/jappmu.2006.235474
M. N. EI-Arian. "PARAMETER ESTIMATES FOR DIRECT AND MATERNAL GENETIC EFFECTS FOR MILK .YIELD TRAITS IN A FRIESIAN CATTLE HERD IN EGYPT". Journal of Animal and Poultry Production, 31, 5, 2006, 2663-2669. doi: 10.21608/jappmu.2006.235474
EI-Arian, M. (2006). 'PARAMETER ESTIMATES FOR DIRECT AND MATERNAL GENETIC EFFECTS FOR MILK .YIELD TRAITS IN A FRIESIAN CATTLE HERD IN EGYPT', Journal of Animal and Poultry Production, 31(5), pp. 2663-2669. doi: 10.21608/jappmu.2006.235474
EI-Arian, M. PARAMETER ESTIMATES FOR DIRECT AND MATERNAL GENETIC EFFECTS FOR MILK .YIELD TRAITS IN A FRIESIAN CATTLE HERD IN EGYPT. Journal of Animal and Poultry Production, 2006; 31(5): 2663-2669. doi: 10.21608/jappmu.2006.235474
PARAMETER ESTIMATES FOR DIRECT AND MATERNAL GENETIC EFFECTS FOR MILK .YIELD TRAITS IN A FRIESIAN CATTLE HERD IN EGYPT
Animal Production Department, Faculty of Agriculture, Mansoura University.
Abstract
Data on 2161 normal lactation records of Friesian cattle raised at an experimental
station during the period from 1996 to 2002 were used. Number of sires and dams
were 92 and 878. respectively .Data were analyzed using MTDFREML program. Two
animal models were fitted .Model 1 considered the animal (additive direct genetic
effects) and the permanent environmental effects as a random effect. Model 2. the
maternal genetic effects was added to Model 1. which allowed for the estimation of
the genetic covariance between the direct and maternal genetic effects. In the two
models fitted. the fixed effects were month and year of calving and parity. Age of cow
at calving was included as a covariate. Direct and maternal genetic effects and
genetic parameters for 305 day milk yield (MY). 305day fat yield (FY) and 305 day
protein yield (PY) were estimated. Estimate of direct heritability of the mentioned traits
was 0.26. 0.24, and 0.26. respectively using Model 1. and 0.31. 0.34. and 0.40.
respectively using Model 2. Maternal heritability estimate was 0.01. 0-06 and 0.13.
respectively. Permanent environmental variance as a proportion of phenotypic
variance was 0.03. 0.11 and 0.11. respectively (Model 1) and 0.12. 0.12 and 0.10.
respectively. (Model 2) .Estimates of genetic correlations between direct and maternal
genetic effects for all milk yield traits studied were negative and ranging from - 0.36 to
— 0.18. Direct genetic correlation between these traits was positive and high. ranging
from 0.95 to 1.00 for Model 1 and from 0.85 to 0.96 for Model 2. Results of the
present study. indicated that the inclusion of maternal genetic effects in the model of
analyses for milk yield traits. is recommended. as. it leads to higher estimates for
genetic parameters.
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