Assessment of sodium status in large ruminants by measuring the sodium-to-potassium ratio in muzzle secretions

Objective-To develop a simple diagnostic test to assess sodium status in la rge ruminants on the basis of the sodium-to-potassium ratio (Na:K) and to d etermine its relevance. Animals-7 buffalo heifers and 21 lactating, pregnant, and nonpregnant; dair y cows and heifers. Procedure-Buffalo heifers were subjected in 2 experiments to variable dieta ry sodium intake or sodium depletion and changes in sodium and potassium co ncentrations; Na:K was simultaneously monitored in various body fluids to s tudy its value for indicating sodium status. Validity of the muzzle secreti on test was assessed. Results-Muzzle secretion and urinary Na:K and sodium concentration, but not serum electrolyte concentrations, reflected the sodium status of buffalo h eifers in response to the widely variable intake of sodium (0.03 to 0.16% o f dry matter [DM]). Progressive sodium depletion during an 11-day period, u sing saliva deprivation caused reciprocal changes in sodium and potassium c oncentrations in saliva and muzzle secretion, but not in urine. Decreasing urine sodium concentration was associated with decreasing urine potassium c oncentration; Saliva; urine, and muzzle secretion Na:K closely reflected th e degree of sodium deficit. Conclusions and Clinical Relevance-Buffaloes or dairy cows maintained on op timal sodium intake had muzzle;secretion and urine Na:K > 0.30. Muzzle secr etion or urine Na:K < 0.20 or < 0.10, respectively. was indicative of sodiu m deficiency. Analysis of muzzle secretion Na:K, and to a large extent urin e Na:K, may be used as a convenient diagnostic-teal to assess sodium status in large ruminants. It has accuracy similar to that of saliva Na:K.