The Preliminary Study On Yili Milk-Horses' Balance Model Between Forage And Animal Under Grazing Condition

From August to September in 2014, the voluntary dry matter intake and nutrition requirements of Yili milk-horse was examined by internal and external indicator method in the grassland of grasses and miscellaneous grass meadow from Zhaosu Horse Farm. From June to October in 2014 and 2015, the main nutrition components and yield of grass was tested as well. Using these parameters, we calculated both grazing capacity of livestock of forage yield and forage nutrient yield and initially proposed the forage horse balance mode.The results are as follows:(1)The range of standing yield in the meadow of grazing land in 2014 and 2015 were31.15~65.35 g·m-2, 83.47~321.76 g·m-2, respectively. The total standing yield of August in2014 and 2015 were 62280 kg, 257408 kg, respectively, and the maximum theoretical yield was 9787.78 g·m-2. The yield of forage in 2015 is significantly bigger than that in 2014.(2)The conventional nutrients of the meadow of grazing land indicated that the content of CP, EE, Ash, ADF, NDF, Ca, P and Ca ? P were 8.54%~16.62%, 0.91%~0.06%,6.65%~13.85%, 28.4%~49.05%, 30.77%~65.35%, 0.92%~1.85%, 0.08%~0.15%, 7.33~23.82,and Ca?P was too high, and horse need supplementing phosphorus.(3)The conventional nutrients of the meadow of grazing land indicated that range of the yield of CP, EE, ADF, NDF, Ash, Ca, P were 7.54 g·m-2~29.79 g·m-2, 0.30 g·m-2~4.25g·m-2, 9.75 g·m-2~104.23 g·m-2, 14.40 g·m-2~140.75 g·m-2, 3.63 g·m-2~24.52 g·m-2, 0.50g·m-2~3.38 g·m-2, 0.02 g·m-2~0.24 g·m-2, respectively. The nutritional value comes to the highest in July, and lowest in October. July is the best time for grazing management.(4)The voluntary dry matter intake, the dry matter feces amount and the apparent digestibility of Yili milk-horse were 15.27 kg·d-1horse-1, 5.28 kg·d-1horse-1, 65.17%,respectively, by internal and external indicator method. The requirements of crude protein and calcium were 1.39, 0.17,-0.021 kg per day. The phosphorus balance was negative andendogenous losing. The forage in Zhaosu meadow steppe may lead to a negative phosphorus balance, and that needs further study. The Ca:P is in a high value, and need supplementing phosphorus.(5)The theoretical yield of grass and DCP were 783028 kg, 60089.6 kg, respectively, in2015. The theoretical grazing capacity of livestock of forage yield were 0.37 hm2·horse-1,320.49 horse·d-1·hm-2, and the carrying horses number was 213.66. The theoretical grazing capacity of livestock of forage nutrient yield were 0.44 hm2·horse-1, 270.19 horse·d-1·hm-2, and the carrying horses number was 180.12. The grazing capacity of livestock of standing forage yield in 2014 and 2015 were 25.31 horse·d-1·hm-2, 86.23 horse·d-1·hm-2; the grazing capacity of livestock of standing forage nutrient yield in 2014 and 2015 were 26.51 horse·d-1·hm-2,59.13 horse·d-1·hm-2, respectively. On the whole,the grazing capacity of livestock of yield was bigger than grazing capacity of livestock of nutrient yield, and we should consider that when making decision about grazing management. In the actual use of the grass, we should combine with two kinds of calculation methods to evaluate the grazing capacity of livestock of native grass, which will help determine a more reasonable pasture grazing capacity and effectively prevent degradation of natural grassland resources.