Excretion of purine derivatives and nitrogen compounds in lactating goats fed other protein sources

In the attempt to simplify the collection of urine samples are collected four hours after the feeding in the morning and urinary creatinine has been used as an indicator of the daily urinary production (Leal et al., 2007). However, there are doubts about possible variation in the excretion of purine derivatives and nitrogenous wastes as a function of time, which would derail the obtainment of a spot urine sampling at any hour of the day. The aim of the present experiment was to evaluate the daily excretions of purine derivatives (PD), urea (U) and total nitrogen (TN) and the ratio of those with creatinine (C) obtained using the spot urine collection, at intervals 2 h, in lactating goats.