Interactions of dietary cation-anion balance and phosphorus: effects on blood, bone and faecal phosphorus concentration in dairy calves.

Dietary levels of cations and anions are shown to have an effect on concentrations of phosphorus (P) in blood, bone and faeces of dairy calves between 9 and 19 weeks of age. Calves fed diets high in anions, demonstrated higher concentrations of P in blood and faeces than calves whose diets were high in cations, and at the same time demonstrated lower concentrations of P in bone. Compared to diets with high cation levels, diets high in anions produced significantly (p less than 0.05) higher concentrations of total P in the faeces at different stages in the experiment, higher serum inorganic phosphorus (SiP) concentrations and lower P concentrations in the bone, which were significant at the end of the trial (P less than 0.06). When the diet was low in P (0.22%), the cation-anion balance of the diet seemed to have the greatest effect, so that the interaction of dietary P and dietary cation-anion balance (DCAB) was responsible for changes in blood, bone and faeces.