| 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.On the base of this, nine diets with different levels of protein and energy content were fed to the cows and the concentrations of purine derivatives (PD) was 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 CNCPS for evaluation to feeds of dairy cows in DAQING region.Fifteen typical feedstuff were collected to analyze the chemical composition by CNCPS system proposed classification of protein and carbohydrate. The results showed that SCP/CP was highest in whole-plant corn silage from Daqing City (68.74%) and lowest in DDGS from Zhaodong City(10.63%); And alfalfa from Qiqihaer City had a very high value of ADL/NDF (19.04%) while corn from Qiqihaer City had the weakest value (6.31%). With respect to the true protein and unavailable fiber content, wheat bran from Nenjing City and alfalfa from Qiqihaer City were in the greatest level (92.58% and 32.50%, respectively), as whole-plant corn silage from Daqing City and cornFrom 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 Daqing region of china since it could reflect the comprehensive nutritional ingredients of feedstuff and metabolisms of digestion and absorption in dairy cows.Exp.2 Evaluation for increasing diary cattle performance and improving diet energy nitrogen balance applying CPM model.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.Exp.3 Relative analysis of PD in urine with different levels of protein and energy.twenty-seven dairy cows with similar parity, DIM and body weight were selected for 3×3 factorial trial to investigate the regularity of UPD 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 0.18:0.82 and 0.19:0.81 in the cows consumed HELP, MELP and LEMP diets, and the cows fed others six diets had the ratio of 0.14:0.86. |
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