Boron Content of Plasma and Urine as Indicators of Boron Intake in Cattle

Abstract

SUMMARY Yearling beef heifers were offered drinking water (0.8 mg of B/L of water) to which 0, 15, 30, 60, or 120 mg of B/L of water was added for 10-day periods. Feed and water consumption were unaffected by treatments. There were no overt signs of toxicosis. Increased B ingestion increased plasma and urine B concentrations. The percentage of renally filtered B that was excreted was increased with the 30, 60, and 120 mg of B/L of water treatments, and B clearance exceeded endogenous creatinine clearance with these treatments. Ingesting increased amounts of B was associated with decreased plasma PO 4 -3 concentration and increased renal clearance and urinary excretion of PO 4 -3 . The B status of cattle can be predicted from plasma or urine B concentrations. Results indicated that prediction can be made from the B/creatinine ratio of urine. With an induced urine sample, the equation for predicting B ingestion is Ŷ = -67.79 + 976.74X - 141.91X 2 ( r = 0.96; S yx = 121.57) where Ŷ is B in milligrams per 100 kg of body weight per day, and X is the ratio of urine B (mg/L of urine) to creatinine (mg/L of urine).