The Study On Growth And Development Of Grazing Lambs In Warm-season Natural Grassland Of Xinjiang

55 Kazak male lambs chosed, lamb weight, body size, nutrient intake, digestion and different parts, different aspects of organs of growth and development were carried out at the north bank of Tekas natural grassland, Zhao Su horse farm, Yili Kazak Autonomous Prefecture in Xinjiang from May 15 to September 28, 2008. The results showed that the entire research period, there was a fluctuation in the growth of lambs pastured as the seasonal Variations in forage. The growth of lambs reached the highest level at 5 months and 7 months, respectively. The body weight gain overally increased. The monthly average daily gain were 187.8±55.7 g,100.1±44.7 g,174.6±45.2 g and 82.1±36.0 g, respectively. There was significant difference in the average body weight gain of the lamb aging 7 or 8 months (P<0.05). However, there was obvious significant difference in average body weight gain of the remaining lamb (P<0.01). Growth rate of pastured lamb body size of 5 months old lamb was bigger than that of 6 months old one, 7 months old lamb was bigger than that of 8 months old. In addition to thoracic deep, the order of the cumulative growth rate of the pastured lamb body size from big to small were chest, body length, body height, thoracic deep, wide chest, tube circuit, respectively. The DM, OM, CP digestion rate of 5 months old lamb were significantly higher than that of 4 months old one(P<0.01). There was decrease in DM digestion rate between 5 and 7 months, the difference between 5 and 7 months was significant (P<0.01). However, there was no significant difference in the DM digestion rate for the rest of the months (P>0.05). The relative growth rate of blood weight, carcass weight, pure meat weight, mental weight of 5 moths old lamb was higher than that of 6 months old, and 7 moths old lamb was higher than that of 8 months old; Throughout the entire research period, the location and the comulative weight of visceral organs had been increased between 4 months and 8 months. Among with the fastest relative growth was on the large intestine (relative growth value of 102.95%), stomach and skin followed by reticulum. The relative growth values were 75.08% and 72.69%, respectively. The slowest relative growth of the organ is the lung (relative growth value of 12.83%).