RESPONSE OF GLUNIERULAR FILTRATION RATE AND PURINE DERIVATIVES EXCRETION TO FEED INTAKE IN BALI AND ONGOLE CROSSED BRED CATTLE

Abstract

Endogenous purine derivatives excretion in urine should be considered in estimating rumen microbial protein synthesis using urinary purine derivatives (UPD) method. This experiment was conducted to examine the response of UPD, nutrient digested and glomerular filtration rate (GFR) to feed intake in different breed of cattle. Four animals of Bali and Ongole Crossed Bred cattle were fed at four fixed levels of feed intake. The highest levels of intake was 90% of voluntary intake and the other levels were 80%, 65% and 40% of voluntary intake. The
treatment was allocated according to 4x4 Latin Square Design. Each period last for 3 weeks. During the last 10 days of each feeding period, sample urine were collected daily for PD and creatinine excretion. Sample feces also collected for, Organic Matter and Dry Matter analyses. Blood samples were taken in every feeding period for crtmtinine and PD content. GFR was calculated based on creatinine content in blood and daily excretion of creatinine in urine. Using
correlation approach, endogenous PD excretion in urine was estimated based on UPD at different level of feed intake. The result show that UPD excretion of cattle receiving 95%.80°/0,60% and 40% of voluntary feed intake were 398, 309, 272 and 214 pmol/MBW/d for Bali cattle and 349, 225, and 203 |_1m0l/lviBW/d for Ongole cattle respectively. There was significant positive correlation between Organic Matter Digested and UPD excretion at different levels of feed intake (P<.01). Endogenous UPD excretion were estimated to be 66 and 74 umol/kg MBW/d for Bali and Ongole Crossed Bred cattle respectively. The GFR of Bali Cattle
tended to increase when the level of feed increased, while GFR of Ongole Cattle were affected significantly by level of feed intake (P<.01). When it was expressed in metabolic body weight the GFR of Bali cattle significantly higher than that of Ongole cattle (10.86 vs. 9.54 If kg MBW/d). It was concluded that the proportion of PD entering the plasma that is excreted in the urine of Bali and Ongole cattle should be studied and taken in to account in the application of Urinary Purine Derivatives (UPD) excretion method for estimating nimen microbial protein.