N-ACETYL-BETA-D-GLUCOSAMINIDASE AS A MARKER OF RENAL DAMAGE IN HENS

Urinary N-acetyl-beta-D-glucosaminidase (NAG) is an early physiologica l indicator of renal damage in several mammalian species. A study was conducted to confirm occurrence of NAG in hen urine, to establish base line urinary NAG in laying hens, and to assess the feasibility of usin g the enzyme as a marker of renal damage in hens. Hy-Line(R) hens were used in a completely randomized block design in the first part of the study. Urine was collected at 4 to 6, 6 to 10, 10 to 14, and 14 to 18 h, and serum at 4, 6, 10, and 14 h postoviposition, and assayed by sp ectrophotometry for NAG. Kidney tissue from additional hens was assaye d histochemically for NAG. Serum NAG (range: 0.11 to 0.14 mU/mg protei n) was found to be several orders of magnitude lower than urine NAG (6 .44 to 12.27 mU/mg protein). Urine NAG increased from 4 to 6 h through 14 to 18 h, indicating that time of collection is critical in order t o utilize the enzyme as a valid marker for laying hens. A preliminary study with five hens indicated that 10 d of treatment with liquid chol ecalciferol (D-3) supplement (three times the recommended level) were not enough to detect renal damage on the basis of significant changes in urine NAG, but elevated urine NAG was detected at 40 d of D-3-suppl ementation. Overall the results indicate that NAG in urine of laying h ens is a potentially useful diagnostic marker of renal damage.