Experiment And Study On The Technologies For Breeding Superfine Wool Sheep Strain In High & Cold Region

Four experiments were conducted to study on a series of techniques for breeding of superfine-wool sheep in high & cold region.Experiment 1 observed growth traits and production performances of hogget ewes born into five different assortative mating groups from both nucleus breeding flock(n:335) and general breeding flock(n:2410). Chinese merino superfine-type ram×objectively selected GA for decreased AFD ewes(K1) and chinese merino fine-type ram×subjectively selected GA for improved fineness number ewes(K6) was the most ideal assortative groups in nucleus and general breeding flocks respectively. The AFD for K1 and K6 was 17.238 and 17.129microns respectively. Compared with experiment assortive groups in general breeding flock, the WWT, ADG, YWT, YSL and CFW was higher by 1.447kg(P<0.001),9.098g/d(P<0.001),3.007㎏(P<0.001),0.266㎝(P<0.01) and 0.35㎏(P<0.001) respectively in the combined experiment assortative groups in nucleus breeding flock, in which objective and intense selection for decreased AFD were used. The experiment assortative mating improved the AFD by 1.351microns and 0.552 microns when compared with the control group in nucleus flock and the experiment groups in general breeding flock respectively. Experiment 2 observed the differences of the growing traits at-and-before weaning and the production performances of hogget GA ewes among four groups divided in terms of their quality number of wool fineness. The results showed that the wool fineness group didn't significantly influence the growth traits of the lambs(P>0.05), with the superfine wool group's adjusted 120-day weaning weight and ADG reached 25.09kg, 186.98g/d and 26.22kg, 193.19g/d respectively for designed common and better supplement management flocks. Although the liveweight before shearing, greasy fleece weight of the superfine group remained the lowest among the groups, the body weight after shearing, CFW and YSL reached 34.18kg, 2.18kg and 9.82cm respectively and there were no significant differences between the groups. The quality score of wool suint color (P<0.05) and wool yield(53.24%, P>0.05) of the superfine wool group was the best among the 4 groups. The AFD of superfine wool group is 17.03 microns . The results demonstrated that the superfine wool sheep can grow and develop normally in this high and cold region. Using MTDFREML software, experiment 3 estimated genetic parameter of AFD and other important breeding traits of GA sheep. The result shows that the heretability of ADG, AFD, CFW, YSL and YWT is 0.41,0.4,0.33,0.4 and 0.78 respectively, and AFD was strongly genetically correlated with CFW(0.9), YSL(0.93) and YWT(0.89) while CFW was strongly genetically correlated with YWT(0.82) and YSL(0.94). In experiment 4, a dye banding technique was used to examine the variation of clean wool growth rate and fibre diameter in different growing period throughtout the year. The result shows that the clean wool growth rate in different seasonal period ranges from 9.935g/d to 24.196 g/d, 6.687 g/d to 14.919 g/d and 3.08 g/d to 15.41 g/d for adult rams, hogget rams and adult/hogget ewes in four groups with two levels of supplement. Clean wool growth rate were significantly different(P<0.001) both between different management flocks in the same growing stage and between different growing stages in the same management flock. The fibre diameter were significantly different between different growing stage(P<0.05) in 5 management flocks with the exception of adult rams. The coefficient of variation of fibre diameter along the staple ranges from 5.778% to 16.26% in all six kind of sheep. The difference of maximum fibre diameter and the minimum fibre diameter along the staple ranges from 3.196 to 7.946 microns.It is concluded that, in breeding of superfine wool strains in high and cold regions, we should pay special attention to selection, assortative mating and animal rearing as the critical technical links. In the selection procedures, it is suggested we should broaden the base population so as to allow wider options for selection. In the process of selection for decreased fibre diameter, the core technique is intensive scanning and combined index selection is advised to be used with enough emphasis on higher clean fleece weight, live weight, staple lenghth and reproduction traits. The influence of age of sheep, sampling method and other environment factors need to be taken into account in measuring the fibre diameter and subsegquent selection activities. The results strongly recommended the open nucleus breeding system be established with intensive scanning, elite rams introducing and positive assortative mating. One important technical challenge for superfine wool sheep breeders and producers in high and cold region is the influence of seasonal change of environment on wool growth rate and especially the eveness of fibre diameter along the staple. Selection for reduced responsiveness to environment changes and balance the nutrient supply throughout the whole year are suggested to solve the problem.