DIETS WITH DIFFERENT RELATIONS OF PROTEIN AND CARBOHYDRATES FOR CATS: EFFECT ON METABOLISM AND PRODUCTION AND FORMATION OF CALCIUM OXALATE UROLITH

Abstract

Cats are carnivores with high amino acid needs. The utilization of carbohydrates has been studied, but some information is not yet well established for the species. The objectives of this study are to evaluate the effect of consumption of diets with different ratios of protein and carbohydrates on the formation and excretion of oxalate and the urinary relative supersaturation for calcium oxalate (CaOx RSS). The study will be organized in two 4x4 Latin squares, each with four diets, four periods of 27 days and four cats, totaling eight replicates per diet. Extruded foods with different proportions of protein (CP) and carbohydrate (CHO) will be evaluated: 20% CP and 48.5% CHO; 34% CP and 33.5% CHO; 48% CP and 18.5 % CHO; and 62% CP and 3.5% CHO. Because of the importance of the food base excess in pH and concentration of oxalate and citrate in the urine, all diets have similar base excess. Cats will remain in metabolic cages for 21 days for diet adaptation, followed by five days of total collection of urine (bottles with 100mg of thymol) and feces. In 24-h urine pool produced will be measured: volume, density and pH. The urine pool will be composed by animal and time and their levels of calcium, phosphorus, chlorine, sulfur, magnesium, sodium, potassium, citrate, oxalate, uric acid, creatinine and pH will be determined. Oxalate will be measured in faeces and food. Plasma blood samples will be collected on the 27th day of each period and analyzed for oxalate, citrate, and creatinine. Based on these results will be calculated the SSR OxCa, the balance of organic oxalate (oxalate ingested - [oxalate oxalate in the feces + urine]) and fractional excretion of oxalate. The results will be submitted to analysis of variance and when significant differences, multiple comparisons will be determined by means of polynomial contrasts (P <.05).Keywords: starch, citrate, base excess, urolithiasis, urine