Effects of CPM model software on diet energy and nitrogen diagnosis, and lactating performance of dairy cows

One hundred twelve China Holstein cows with similar body weight and lactation stage were selected. The average daily milk yield of one half was 20.34 +/- 1.61kg and the other was 25.41 +/- 2.97kg. In each herd, the cows were randomly assigned to two groups. The control diets (I and II) were the original dairy farm diets, and the test diets (I and II) were the corresponding control diets adjusted by CPM-Dairy (Cornell-Penn-Miner Dairy System). The diagnosis for the two original diets showed the ME and MP balance were greater than the cow requirement. The rumen peptide balance also showed the same tendency. Both test diets had lower CP (%/DM) than the corresponding Control diet by 1.60% and 2.5%, respectively. However, both the RUPs (%/CP) were increased a little in the two test diets. The MP allowed daily milk yield of Control diet I was greater than the actual daily milk yield and ME allowed daily milk yield (P < 0.05), but they didn't present significant difference in Test diet I (P > 0.05).