Influence of cation-anion balance on feed intake, body weight gain, and humoral response of dairy calves.

The objective of this study was to examine the influence of diets with varying cation-anion balance on performance and humoral responses in young, growing dairy calves. Twenty-eight Holstein and 4 Jersey female calves were blocked at 56 to 70 d after birth according to breed and age and assigned randomly to dietary treatments of 0, 21, 37, and 52 meq(Na + K) - Cl/100 g of dietary DM. Diets were based on cracked corn, dried brewers grains, and oats and were fed for 8 wk. Feed intake and average daily gain tended to increase quadratically, being highest for calves fed the +37-meq diet and lowest for those fed the 0-meq diet. Blood and urine pH increased linearly with increasing dietary cation-anion balance. Plasma Ca increased linearly, and Mg and Cl decreased linearly with increasing cation-anion balance. Plasma Na and P were unaffected by dietary treatments. Urinary Ca, Mg, and Cl excretions decreased linearly; urinary P, Na, and K excretion increased linearly with increasing dietary cation-anion balance. Blood pH increased linearly with increasing dietary cation-anion balance. Blood partial pressure of CO2 and HCO3 increased concurrently with increasing dietary cation-anion balance. Results indicate that altering cation-anion balance may impact DMI and average daily gain in the young ruminant.