Interactions of Dietary Cation-Anion Balance and Phosphorus: Effects on Growth and Serum Inorganic Phosphorus in Dairy Calves

Thirty-six male and female Holstein and Jersey calves were assigned at weaning to a randomized complete block design in a 2 x 3 factorial arrangement to evaluate the influence of two dietary cation-anion balances (-14 and +39 meq(Na + K)-(Cl + S) per 100 g diet DM) and three amounts of dietary P (.22, .29, and .37%) on performance and P metabolism from 9 to 19 wk of age. Feed intake, average daily gain, and serum inorganic P were higher on the anionic diets and increased with increasing dietary P. Body weights were higher on the .37% P diets by wk 3 and on the anionic diets by wk 6. The interaction of dietary P and cation-anion balance was responsible for significant differences in calf performance; the anionic diet exhibited marked improvement over the cationic diet at the lowest P concentration. Results indicate that the availability of P for young dairy calves may be higher with anionic than cationic diets.