| In this study, twenty-three typical feed were collected from northeast agricultural region to analyze the chemical composition using CNCPS model and estimate their nutritive value. Meanwhile, two kind of dairy diets (for the cows of 20 and 25 kg milk production) common used in diary farm were evaluated according to the CPM-Dairy 3 version model of CNCPS to find out whether CPM model could be effectively applied in the evaluation and prediction of dairy performance. Nine diets with different levels of protein and energy content were fed to the cows and the concentrations of purine derivatives (PD), creatinine (C), PD:C in urine and milk and milk urea nitrogen (MUN) were determined to investigate if they could reflect the information of protein and energy level in the diet and then to lay the foundations of development of more effective, convenient and reliable method for dairy nutrition measurement.Exp.1 was conducted to expand the application of CNCPS to enrich the nutrition database of feedstuff common used in dairy industry in the Northeast of China. Twenty-three typical feedstuff were collected to analyze the chemical composition, such as crude protein (CP), non-protein nitrogen (NPN), soluble crude protein (SCP), acid detergent insoluble protein (ADIP), neutral detergent insoluble protein (NDIP), acid detergent fiber (ADF), neutral detergent fiber (NDF), acid detergent lignin (ADL) and starch, according to the classification method of CNCPS. Then the contents of non-protein nitrogen (PA, % CP), rapidly degraded protein (PB1, % CP), intermediately degraded protein (PB2, % CP), slowly degraded protein (PB3, % CP), bound protein (PC, % CP), unavailable fiber (CC, % CHO), available fiber (CB2, % CHO), starch, pectin (CB1, % CHO) and sugar (CA, % CHO) were calculated respectively following the formula provided in CNCPS. The results showed that SCP/CP was highest in whole-plant corn silage (From Daqing City, 68.74%) and lowest in wet brewer's grains (From Shenyang City, 4.12%); And apple pulp (From Anshan City) had a very high value of ADL/NDF (34.51%) while barley (From Shenyang City) had the weakest value (2.46%). With respect to the true protein and unavailable fiber content, soybean (From Shenyang City) and apple pulp (From Anshan City) were in the greatest level (97.07% and 65.01%, respectively), as whole-plant corn silage (From Daqing City) and corn (From Qiqihaer City) had the lowest value (26.81% and 1.6%, respectively). It concluded that the application of CNCPS could be extended in the evaluation of feedstuff of dairy cows in the northeast agricultural region of china since it could reflect the comprehensive nutritional ingredients of feedstuff and metabolisms of digestion and absorption in dairy cows. In Exp. 2, Twenty-three typical feedstuff from northeast agricultural region of china were collected to analyze the amino acid The results showed that in 17 kind of amino acid , Met content (%DM) was highest in dry brewer's grains (From Shenyang , 0.32%) and lowest in maize stover (From Daqing , 0.06%); the concentration of Lys (%DM) was highest in soybean meal (From Jiushan, 2.86%) and lowest in compressed maize stover cake (From Shenyang , 0.28%). When it comes to the content in CP, Met (%CP) was highest in maize stover (From Daqing , 1.82%) and lowest in alfalfa (From Qiqihar, 0.52%); Lys (%CP) was highest in soybean meal (From Jiushan, 5.94%) and lowest in corn grain (From Qiqihar, 2.16%).Exp. 3 was carried out to investigate the application of CPM model in evaluation of dairy ration and prediction of animal performance. Fifty-six dairy cows with similar parity, DIM and body weight were selected and divided into two groups according to the milk production (20 kg and 25 kg). Then paired test was conducted in each group. The diet applied in the dairy farm was denoted as the control and the diet adjusted by CPM model was denoted as the treatment. The trial lasted for 45 d. The results showed that, milk yield, 4% fat corrected milk yield, blood urea nitrogen (BUN) and MUN content were slightly higher in the cows fed the adjusted diet than those fed the control (P>0.05). In group I, The milk fat percentage was lower in the cows fed the control (P>0.05), but milk protein percentage was not altered. But in group II, the cows fed adjusted diet had lower content of milk fat and protein (P>0.05). After adjustment, the cost were decreased by $2.43/d and $2.12/d compared with the original diets, respectively. The difference between the predicted and determined value of milk yield and DMI was less than 6% and 5% with the exception of those in the control diet of group I. In conclusion, the CPM model of CNCPS could effectively predict the nutritive value of dairy ration and decrease the feeding cost without any impair in animal performance.In Exp. 4, twenty-seven dairy cows with similar parity, DIM and body weight were selected for 3×3 factorial trial to investigate the regularity of UPD, UC and UPD:UC in urine of cows fed different diets using complete urine collection method. The treatments were three levels of metabolism energy supplement in the diet (127%ME/Require ME, 100%ME/Require ME, 75% ME/Require ME) and three levels of metabolism protein (123% MP/Require MP, 100% MP/Require MP, 80% MP/Require MP) by CPM-Dairy 3 version model. The results showed that when the metabolizable protein content was constant, the concentration of UPD was increased with the increasing level of metabolizable energy and the concentrations of uric acid (8.24-22.75 mmol/d) , allantoin(49.61-137.10 mmol/d)and total UPD(57.85-159.86 mmol/d) had similar tendency. When the metabolism energy was at the same level, the content of UPD increased when metabolizable protein level increased. Linear relationships were found between the contents of allantoin, uric acid and total UPD and the protein and energy level in the diets. The ratio of content of allantoin and uric acid was 0.12:0.88 in the cows consumed HELP, MELP and LEMP diets, and the cows fed others six diets had the ratio of 0.14:0.86. The UC content (46.70-59.16 mmol/d)was not affected by the ration. The ratio of UPD to UC (1.07~2.95) was significantly correlated with the level of energy and protein in the diet.Exp. 5 was conducted to find out the regularity of UPD, UC and UPD:UC in urine of cows fed different diets using spot urine collection method. Its treatments were as same as in Exp. 4.The results showed that uric acid(1.06-3.49mmol/L), allantoin(5.86-19.59mmol/L)and total UPD content(6.92-23.08mmol/L)had the same tendency with the data in Exp. 4. The ratio of uric to allatoin was in the range of 0.15:0.85~0.17:0.83. The uric acid, allatoin and UPD content in diary urine were linearly correlated with energy and protein level of rations. The UC content(7.72-13.40mmol/L)was not changed when the energy and protein level differed in the diet. The ratio of UPD to UC (0.80~2.54) measured by spot urine collection had a strong correlation with those measured using complete urine collection (R=0.8862). It was concluded that the concentration of UPD and UPD:UC could reflect the information of energy and protein level in the diet, and what's more, UPD:UC value could be determined by spot urine collection in stead of complete urine collection.Linear equation of UPD and UPD:UC with energy and protein level of ration by complete urine collection y? upd = ?145.5429(26.2291)+0.9718(0.2504)x1 +1.4663(0.2799)x2 y? upd / c= ?2.3360(0.5377)+0.0190(0.0051)x1+0.0223(0.0057)x2 Linear equation of UPD and UPD:UC with energy and protein level of ration by spot urine collection Y?u pd = ?26.3184(4.2510)+0.1119(0.0406)x1 +0.2697(0.0454)x2 Y?u pd / c=7.6026(2.9748)?0.0837(0.0280)x1?0.0818(0.0315)x2?0.0010(0.0003)x1x2Exp. 6 was conducted to find out the regularity of MPD, MC and MPD:MC in milk of cows diets with different levels of protein and energy. The results showed that when the metabolizable protein content was constant, the content of MPD increased as the metabolizable energy level increased and it had the similar tendency with the UPD content. The concentration of uric acid in milk(0.44-1.22 mmol/L)increased with the increasing level of the metabolism energy in diet when the content of metabolizable protein was at the same level. The allantoin content in milk was increased with the increasing level of energy except those in low protein level diets. The content of allantoin was highest in MELP diet and lowest in LELP, and HELP was in the intermediate. But there were no significant differences between them (P>0.05). The uric acid and total MPD contents in milk were linearly correlated with energy and nitrogen levels of diet, but the concentration of allantoin in milk was altered by the treatment. MC content was changed from 2.77 to 7.27mmol/d, it was about 5.93-12.28% of the UC content measured by complete urine collection, and they had similar tendency. The ratio of MPD to MC was varied from 0.27 to 0.53, and it was about 17.96-25.23% of the value measured by complete urine collection. There was not linear relationship between the MC content, MPD:MC value and the level of energy and protein in dairy diets.RDP, energy level and energy nitrogen balance in cows ration could be reflected by MUN contents. In this experiment, variation of MUN of cow diets with different levels of protein and energy was found to have regularity. That was when the metabolizable energy was in middle energy level or more, the content of MUN increased as the metabolizable protein level increased , and when metabolizable energy was in low level, the content of MUN in LEMP diet higher than in LEHP diet(P>0.05)and both significantly higher than in LELP diet.when the metabolizable protein in cow ration was in middle and low energy level, the content of MUN decreased as the metabolizable energy level increased, and when metabolizable protein was in high level,the content of MUN in MEHP diet higher than in LEHP diet(P>0.05)and both significantly higher than in HEHP diet(P<0.05).In this experiment, It was conclude that the content of UPD, UPD:UC and MUN could effectively reflect and evaluate the energy and protein level in the diet according to the correlation analysis in the present study.
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