Protein for calves on a limited milk-early weaning system

Complete pelleted calf starter rations were fed to Holstein heifer calves on a limited milk-early weaning program from 3 days to 12 wk of age. Five rations fed to each of 10 calves were to contain crude protein percentages of 10, 12.5, 12.5 with 97% urea, 15, and 15 with 1.1% urea (as fed). The digestible protein:digestible energy ratios (g digestible protein/Mcal digestible energy) of the rations (in same order) were 23.4, 30.7, 28.8, 36.4, and 41.5. Average birth weight was 42.9 kg and weaning weight at 4 wk, 52.8 kg. Treatment effects on feed intake, average daily gain, and feed efficiency were analyzed after adjustment of birth weight and removal of effects of block and location. Feed intake for 12 wk was greater for 15% crude protein with 1.1% urea than for either 12.5% ration but not different from 10% protein. Average daily gain was increased for 15% protein rations compared to 10 or 12.5% protein. Gain by claves fed 10% protein was equal to that by those fed 12.5% protein. Feed efficiency during wk 5 to 12 was improved for 15% with vegetable protein compared to 10% crude protein or the 12.5% crude protein ration with vegetable protein. There were no differences in intake, gain, or efficiency between urea and vegetable protein.