Potassium requirement of dairy calves

Thirty-five Holstein and Jersey calves were blocked according to breed and sex, then randomly assigned at 4 wk of age to four dietary concentrations of K (.55, .84, 1.02, or 1.32% of DM) for a 10-wk period. Plasma K, Na, Ca, and Mg; body weight change; and feed intake were similar among the four treatments, as was average daily gain, which averaged .73 kg across all diets. In a second trial, 16 Holstein calves were blocked according to sex and randomly assigned at 6 wk of age to two concentrations of dietary K (.34 and .58% of DM) for an 8-wk period. Plasma Ca was higher at wk 8, and plasma Mg lower at wk 4, on the .58% K diet, while plasma Na and K were unaffected by dietary K concentration. Average daily gain for the .58% K group was .74 kg compared with .60 kg for calves receiving .34% K. In addition, both feed intake and body weight change were higher during the last 4 wk of the trial for the calves fed .58% K. As a result of the increased performance exhibited by the calves receiving .58% K, we conclude that the dietary K requirement of the growing dairy calf is within the range of .34 to .58%.