| This paper was on the basis of the demand of Qinghai Fine-wool sheep production and breeding. The breeding objective traits was determined by systems analysis method, and marginal profits for each target trait was calculated by balance method. The genetic parameters for growth traits and wool traits were estimated with different animal models. After this, based on gene flow method, the software ZPLAN was use to analysis closed nucleus breeding programs and open nucleus breeding programs for Qinghai Fine-wool sheep. The results were shown:1. Three target traits and seven types of selection traits were determined. The target traits contained wool traits, growth traits and reproduction traits. Selection traits were net fleece weight, fiber diameter, staple length, weaning weight, yearling weight, hogget weight, number of kids weaned.2. The marginal profits for selection traits were52.176,21.854,-17.646,-7.391,4.117,1.725,1.401,0.761,6.742,88.066for net fleece weight of adult female sheep, net fleece weight of young sheep, fiber diameter of adult female sheep, fiber diameter of young sheep, staple length of adult female sheep, staple length of young sheep, weight of adult female sheep, weight of young sheep, weaning weight and number of kids weaned, respectively. The economic weight proportion of wool traits, growth traits and reproduction traits was0.623:0.225:0.152, similar to4:1.5:1.5. Model3(y=Xβ+Zaa+Zmm+e)were fitter for birth weight, weaning weight, and model1(y=Xβ+Zaa+e)were fitter for yearling weight, hogget weight; model13(y=Xβ+Zaa+Zpp+Zss+e)was fitter for wool greasy fleece weight; model12(y=Xβ+Zaa+Zmm+Zss+e)were fitter for fiber diameter and staple length. The direct heritabilities were0.1995,0.2552,0.3438,0.2205,0.1477,0.2226,0.1182for birth weight, weaning weight, yearling weight, hogget weight, greasy fleece weight, fiber diameter and staple length respectively.4. After optimizing the proportion of sex for lamb in the closed nucleus breeding scheme, the results shown that when male was0.3and female was0.95,the breeding scheme would make best breeding efficiency. The optimizing various factors of population structure research shown that when the proportion of nucleus was0.04, the proportion of production herd was0.90, ram used1year and ewe used4years in nucleus flock, ewe used4years and ram used3years in breeding flock, the YSN was utilized0.2by production herd, the breeding scheme would gain best breeding profit.5. The inbreeding research shown that when remained more ram and extended the useful life of ram in nucleus, the inbreeding would reduce in the closed nucleus breeding scheme.6. After optimizing the proportion of sex for lamb and closed level of nucleus in the open nucleus breeding scheme, the results shown that when male was0.4and female was0.9, the closed level of nucleus0.8-0.85, the breeding scheme would make best breeding efficiency. The optimizing various factors of population structure research shown that when the proportion of nucleus was0.08, the proportion of production herd was0.85, ram used1year and ewe used3years in nucleus flock, ewe in breeding flock returned back to nucleus used2years, ewe used3years and ram used6years in breeding flock, the closed level of nucleus0.95, the YSN was utilized0.9by production herd, the breeding scheme would gain best breeding profit.7. In the open nucleus breeding scheme, the inbreeding results were similar to results of the closed nucleus breeding scheme.8. Comparing closed nucleus breeding system and open nucleus breeding system shown, in the current breeding, the open nucleus breeding system would get better breeding efficiency. Optimizing the proportion of sex for lamb and various factors of population structure shown that the open nucleus breeding system was better. The inbreeding research shown, when reasonably controlled the number of ram and the useful life of ram, the upward trend of increasing inbreeding would be slowdown. |
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