Study On Prediction Model Of Herbage Intake And Optimization Supplementation Of Semiconfinement Dairy Cow In Agri-pastoral Transitional Zone

The present study included three parts.Part one was conducted to determine dry matter intake,pasture botanical composition and pasture DM digestibility in grazing diary cows using alkane technique, and to monitor the dynamic changes of pasture nutrients in different periods.Part two was conducted to select the best prediction model, which could get the dry matter intake of herbage close to the value measured actually, based on a comparison analysis beteen measurement and prediction,and study the influencing factors of prediction model of herbage intake, and then improve the model.Lastly, the fittest prediction model of pasture dry matter intake was established for semiconfinement dairy cows in Agri-pastoral Transitional Zone.Part three was conducted to predict pasture intake by using the prediction model , and then draw up a programme of optimization supplementation of semiconfinement dairy cows in Agri-pastoral Transitional Zone based on feeding trials.Part one: Dry matter intake, pasture botanical composition and pasture DM digestibility in grazing diary cows were measured in three different growth periods of pasture (young pasture,growing pasture and scorch pasture) using alkane technique in the typical Agri-pastoral Transitional Zone (Xi Meng Bai Qi),and the grass characteristics and pasture nutrients were measured too.The results showed: (1) In the three different periods, PDIM was 11.34 kg/d,12.44 kg/d and 7.01 kg/d, respectively.(2) The young pasture intaked included Carex liparocarpos Gaudin,Artemisia frigida Willd,Cara gana stenopA.ylla Pojark,Stipa breviflora Grised,Leymus secalinus (Georgi) Tzvel; the growing pasture intaked included Stipabreviflora Grised,Artemisiadalai–lamaeKrasch,Cleistogenes songorica Ohwi,Leymus secalinus (Georgi) Tzvel;and the perishing pasture intaked included Stipa breviflora Grised , Leymus secalinus (Georgi) Tzvel , Caragana stenopA.ylla Pojark.(3) The hight,density and coverage of pasture varied in different growth periods , and under the same stocking rate, pasture allowance was 37.08 kg/head·d ,48.55 kg/ head·d,and 22.08 kg/ head·d in the three periods, respectively.(4) Following the change of pasture growing periods,the nutrition of pasture decreased gradually,lignification increased,so the digestibility decreased gradually (78.34%,77.15% and 54.99%,respectively).Part two: The comparision was conducted between pasture intake measured actually and that predicted by prediction models, and it was discoveded that the predicted intake by the prediction model involving grass characteristics and animal factors was close to the intake value measured actually.For example, Vazquez and Smith (2000) put forward PDMI prediction model:PDMI = 4.47 + ?0.14FCM + ?0?.024BW +? ?2.00CBW + 0.04PA +? 0.022PASUP ?-? 0.90SUP -? ? 0.13NDFp - 0.037LEG. The study on influencing factors of prediction model showed that the correlation coefficient between pasture intake and pasture allowance was 0.97, and that between pasture intake and supplemented feed level was 0.89. Lastly, prediction models of pasture intake were established as follows: PDMI=1.07+0.042FCM+0.062BW+0.12PA-0.38SUP-0.017NDFp(R2=0.89) PDMI=6.68+0.14FCM+0.024BW+0.14PA+0.024PASUP-0.04SUP-0.13NDFp(R2=0.87)Part three: Pasture intake in perishing period was predicted using the established prediction model,and verified with the value measured actually.Considering the limiting nutritional factors of Agri-pastoral Transitional Zone,the supplemental diets of grazing diary cow were designed.The results of optimum supplemental test showed that the body condition of diary cows gradually returned to normal in optimum group. which was beneficial to fetal growth and service life. In addition, milk yield increased by 2.73 kg/d, and the economic profit increased by 23.04%.