Urinary Excretion Of Purine Derivatives In The Male Calves At The Age Of 4 To 12 Months

This paper studied the effects of different nutrition level to the urinary excretion of purine derivatives in growing calves and included the following three experiments.Three Holstein male calves with 120+6 days old and 76+4Kg body weight were used in the first experiment. The ratio of the nutrition in daily intake is stable at all state of the experiment. According to the PD excretion and its components discovered in the study, this experiment can be divided into two states: month 4⁹ and month 9¹2. In the first state, the total excretion of PD was very low and varied from 0.26 to 0.38 mmol/KgBW0.75/d, moreover, the ratio of uric acid was very high and varied from 50 % to 80%. In the other state, the PD excretion suddenly increased to 0.60 mmol/KgBW0.75/d and went up slowly to 0.68 mmol/KgBW0.75/d, at the same time, the ratio of the uric acid decrease linear to the normal level of adult cattle and then keep stabilization. In this study two equations were available from the relativity of PD excretion(Y) with age(X) and DOMI (X), as follows respectively: y = 0.124e^0.1424x (R2 = 0.94, n=8), y =3.81e^0.76x , (R2 = 0.84 , n=24). The results showed that the age was the main factor to effect the urinary excretion of PD before month 9 and then was DOMI after month 9. The creatine excretion also increased with the rise of age and DOMI, the highest excretion in the experiment is 2.33+0. 65mmol/KgBW0.75/d, which is far more than the result of current reseach in other species of cattle. PDC index decreased with the increase of age before month 11, and after that began to increase.Another three Holstein male calves with 130 + 15 days old and 96+4Kg body weight were used in the second experiment. This experiment was design to study the influence of different forages to PD excretion. The results showed, the excretion and the components of PD were similar to that of the same terms in the first experiment. As for the effect of different forages, different ratio of concentrate to forage and different DM intake, the DOMI, DCP, DE increased, and the excretion of PD and creatine increased from 3.85 to 9.10 and 3.15 to 22.22 mmol/d respectively.The calves used in the second experiment were continue used in their month 10¹2 in the last experiment and the diet were designed with three different protein level of 10.07%, 12.19%, 14.29%. As a result of increasing protein level, the apparent digestion rate of DM, OM, CP and DE increased evident. At the same time, the uric acid ratio in PD have already got to the normal level of adult cattle and the correlation of DOMI and PDC shows positive relativity. The relativity equation is Y=15.675X— 21.207, (R2= 0.7162, n=9) , Y represents PDC and X represents DOMI (Kg).