IS THERE AN OPTIMAL CATION-ANION DIFFERENCE FOR LACTATION DIETS

Because of the increased use of the cation-anion difference (CAD) conc ept in dry cow nutrition, many dairy nutritionists have been asking wh ether or not CAD is important in lactation diets, Two common questions are: (i) should CAD be monitored in rations formulated for lactating dairy cows?; and, (2) what is the optimal CAD for high producing dairy cows? A project was initiated to answer these questions. We combined data from ten macromineral nutrition experiments and conducted a regre ssion analysis, This data base contained a wide range (+5.8 to +61.2) of dietary CAD (defined as the meg of Na + K-Cl per 10D grams of diet DM), Regression models indicated that the optimal CAD for lactation ra tions was between +25 and +50. Dietary CAD should be routinely monitor ed in rations fed to high producing dairy cows, however, commercial di ets with CAD values outside the optimal range are probably uncommon.