The physiological mechanism of low purine derivative excretion in urine of buffaloes

Three cattle calves and three buffalo calves were weaned after receiving colostrum and reared by bottle feeding of milk. During the first month the animals did not have access to solid food. Urinary purine derivatives (PD), basal PD excretion and glomerular filtrate rate (GFR) were determined. After one month the animals were given access to solid feed (urea-treated rice straw) to stimulate rumen development. After three months of age, during which time the solid food was given, urinary PD, basal PD excretion and GFR were again determined. Urinary PD excretion, both during fasting and milk feeding, was not different between buffaloes and cattle in the milk feeding period, but there were differences between cattle and buffaloes after 3 months of age and two months of access to solid feed. The GFR was lower in buffaloes in both milk fed and solid fed calves, while the excretion of PD in the milk feeding period was similar between the two species. It is concluded that the lower GFR in buffaloes is a condition allowing PD to stay longer in the blood thus there is more time for recycling to the rumen and to be metabolized by bacteria.