Estimation of the Microbial N Flow to Small Intestine in Saanen Goats and Kids Based on Urinary Excretion of Purin Derivatives by the Use of Spot Urine Sampling Technique

Abstract

The objectives of the present study were to estimate the microbial N flow to small intestine and to predict the digestible organic matter intake in Saanen goats and kids based on urinary excretion of purin derivatives (PD) by the use of spot urine sampling technique under the field condition. In the experiment, 10 Saanen does (3 years of age) and 10 Saanen female kids (1.5-2 months of age) were used. The mean live weights of goats and kids were 42+/-3 kg and 7.5+/-2.5 kg respectively. Goats were fed by concentrates and grass hay in the morning and evening. They were also allowed to grazing throughout the day. Kids were only suckled milk from their mothers. After the morning feeding, spot urine samples from goats and kids were collected in between 10: 00-12: 00 a. m. Urine samples collected into a cup containing 0.5-1 ml of 4 N H2SO4 to keep the urine pH under 3. The levels of urine allantoin, uric acid and creatinine were determined by the use of spectrophotometric methods. The mean values of allantoin, uric acid, total PD and creatinine were 5.93+/-0.07, 1.91+/-0.10, 7.84+/-0.14 and 5.75+/-0.08 mmol/L of goats; 4.70+/-0.09, 1.33+/-0.07, 6.33+/-0.11 and 5.07+/-0.05 mmol/L of kids respectively. The estimated microbial N flow to small intestine for goats 8.45+/-0.13 g N/d and 1.84+/-0.04 g N/d for kids. Daily digestible organic matter intake in Saanen goats was estimated as 665.90+/-18.92 g/d. The estimated microbial N values show that protein nutrition of goats and kids seem insufficient under the field condition concerned. In conclusion, the prediction of protein nutrition of goats under the field condition may be possible by the use of spot urine sampling techniques, urinary excreted PD and purine derivatives: Creatinine (PDC) index.