Effects of dietary cation-anion difference on performance and acid-base status : a review

Abstract

Improving food practices of high producing animals is required to avoid important economic losses. The dietary anion-cation difference, described as [sodium] + [potassium]-[chlorine], should aid in preventing metabolic disorders caused by acid production. From three databases (dairy cows, growing pigs and growing ruminants), performance and acid-base status responses on an increase of dietary cationanion difference were studied by a covariance analysis. Intake, 4% fat corrected milk and average daily gain increased with increasing dietary cation-anion difference. At the same time, blood pH and blood bicarbonate concentration increased whereas blood chlorine decreased, suggesting that chlorine is the main ion implicated in the acid-base regulation. The urinary pH increased with increasing dietary cation-anion difference and it was highly correlated with the dietary cation-anion difference. Renal excretion was the main way to excrete ions and urinary pH seemed to be a good predictor of dietary cation-anion difference. The results suggest that an increased dietary cation-anion difference could prevent metabolic disorders due to an intense metabolism. Moreover, the results suggest that the main way to improve performances is based on a systemic level, even though a rumen effect could explain the difference between ruminants and pigs.