Study On The Production Performance Of Tianzhu Mutton Merino Breeding Group

Tianzhu county is a traditional fine wool sheep production area in Gansu Province.In order to protect the fine wool sheep resources and achieve the goal of increasing meat production,our research team began to cultivate a new breed of Mutton fine wool sheep in 2009,named Tianzhu Mutton Merino sheep,which combines the characteristics of fast growth speed,good meat performance of male parent South Africa Mutton Merino,and good adaptability to cold and high environment of female parent Gansu Alpine Fine Wool Sheep.In this paper,the core breeding group of Tianzhu meat Merino new breed was selected as the experimental object.Firstly,the body weight,body size and some carcass traits of the first generation of yearling ewes in the breeding group were measured.Secondly,the wool quality of the first generation of adult ewes was measured under the conditions of grazing supplement and house feeding.Finally,the growth prediction model of the second generation male and female lambs were established.Improving the basic data of production performance of Tianzhu Mutton Merino new breed breeding group can provide a reference for selection and matching.The main research results are as follows:1.The average body weight of the first generation yearling ewes of Tianzhu Mutton Merino breeding group was 50.15±6.74kg,body height,body slant length,chest circumference and tube circumference were 69.70±3.22cm,72.39±4.54cm,103.17±7.01cm and 9.77±1.23cm,respectively.The optimal regression equation between body weight and body measurement of first generation of yearling ewes is Y=0.509X₁+0.560X₂+0.383X₃-0.858X₄-56.858.The backfat thickness,eye muscle thickness and eye muscle area of first generation of ewes were measured by B-ultrasound,which were 8.16±2.03mm,2.43±0.43cm and 20.25±4.65cm².The trend equation of carcass traits with body weight was established.The coefficient of determination were backfat thickness and body weight（R²=0.144）,eye muscle thickness and body weight（R²=0.127）,eye muscle area and body weight（R²=0.458）.2.Determination of wool quality of adult ewes of new breed breeding group of Tianzhu Mutton Merino under different feeding conditions.The length of side wool of grazing and supplementary feeding sheep is 9.05±0.93cm,and that of house feeding sheep is 8.24±1.32cm;the weight of grazing and supplementary feeding sheep after shearing is 50.62±7.91kg,and that of house feeding sheep after shearing is66.03±12.41kg;according to the national standard NY-1-2004"identification of fine wool sheep",the quality traits of fine wool in three grazing and supplementary feeding and expansion farms are identified subjectively by 3-point system,with an average identification score of more than 2 points.The average fiber diameter of the side wool was 20.21±1.96μm under the condition of grazing and supplementary feeding,and 18.98±2.12μm under the condition of shed feeding.The wool cleaning rate was determined according to the national standard oven method（GB/T6978-2007）.The clean fleece rate of the three pastures were 47.14±5.13%,48.08±5.84%,43.63±5.62%and that of the feedlot was 49.37±7.17%.3.The birth weight of male and female lambs in the second generation of Tianzhu Mutton Merino new breed breeding group was 4.34±0.70kg,3.97±0.96kg,weaning weight was 21.82±4.33kg and 21.88±3.75kg for male and female lambs,and the six-month age weight was 50.96±5.43kg and 44.34±6.19kg respectively.The average daily gain of male and female lambs of the second generation before weaning was260.37±62.80g/d and 246.14±50.06g/d,respectively.The average daily gain from weaning to six months was 253.74±34.83g/d and 186.59±44.49g/d,respectively.The growth parameters predicted by Gompertz model were more in line with the actual production situation.Compared with the first generation of lambs,the age of male and female lambs’turning point was advanced to 59.52d and 47.83d,and the weight of turning point was increased to 21.64kg and 17.66kg.