Urinary excretion of purine derivatives as influenced by GFR and plasma retention of purines in cattle (Bos indicus x Bos taurus) and buffalo (Bubalus bubalis) bulls

Abstract

A study was undertaken to assess the influence of variation in the glomerular filtration rate (GFR) and plasma retention of purines on excretion of purine derivatives (PD) in crossbred cattle and buffalo bulls. Five male crossbred cattle (Bos indicus × Bos taurus) and Murrah buffalo bulls (Bubalus bubalis) about 2 years and 2 months of age (average body weights: 198.2 and 214.6 kg, respectively) were fed a maintenance ration containing wheat straw and concentrate. Experimental feeding of 40 days was followed by a metabolic trial of six days. The response parameters were compared by the independent T test. The plasma allantoin, uric acid, and total PD concentrations were higher (p < 0.05) in cattle than in buffalo. Urinary allantoin and total PD excretion were higher in cattle (p < 0.05). Creatinine excretion however, was comparable (p > 0.05) between the two species. The GFR in both groups remained similar. The tubular loads of allantoin, uric acid, and total PD were numerically higher in cattle, whereas, the uric acid reabsorption percent was higher (p < 0.05) in buffaloes. The microbial nitrogen supply was higher (P< 0.01) in cattle. The purine nitrogen index remained similar in both species. The present study concludes that the lower urinary PD excretion rate of buffalo was due to their higher reabsorption of PD than cattle; however, the effect of species-specific GFR seems to confound the elucidation of the variation in their individual urinary PD excretion.