Genetic models for improvement of sheep inEgypt.
Abstract: Estimating the variance and covariance structures of' weaning weight (WW) and each of kilograms weaned at the 1st parity (KGW1) and total kilograms weaned (TKGW) of the first three seasons and those of yearling weight (WT12) and each of KGW1 and TKGW of the first three seasons in local breeds (Rahmani and Ossimi) was the first objective of this study. Estimation of the heritabilities and genetic correlations for and among the studied traits formed the second objective. While the third objective was concerned with comparing independent culling level (ICL) and selection index (SI) for improving WW and KGW1.
The animal model with MTDFREML procedure was used to estimate the variance components and genetic parameters for the studied traits. Heritability estimates for WW, WT12, KGW1 and TKGW ranged from 0.24 to 0.72, from 0.26 to 0.54, from 0.08 to 0.11 and from 0.27 to 0.47, respectively in both breeds. Genetic correlations among the studied traits were positive and ra.nged from high estimate (0.87) between WW and KGW1 in Rahmani sheep to low estimate (0.10) between WW and TKGW in Ossimi sheep.
The genetic gains for WW and KGW1 were 0.66827 and 1.01707, 0.2445 and 0.3832 under the current selection policy of the Egyptian Ministry of Agriculture flock using ICL and SI, respectively. While, it could be improved to 0.80654 and 1.23174, 1.0167 and 1.5935 under the ICL and SI, respectively by changing the flock structure. The total costs required for each one kilogram weaned through selection programs presented in this study were 16.27,18.30,15.36 and 15.37, respectively.
Key words: Sheep, Lamb body weights, Productivity, Variance components, Independent culling level and Selection index.
Publication year 1998
Availability location مكتبة معهد بحوث الانتاج الحيوانى - شارع نادى الصيد - الدقى - الجيزة
Availability number 610
Organization Name
Country Egypt
Department Sheep and Goat Research Department
Author(s) from ARC
Agris Categories Animal husbandry
AGROVOC
TERMS		 Culling. Genetic covariance. Lambs. Productivity. Selection index. Sheep.
Publication Type PhD Thesis
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