Evaluation of some urinary parameters in beef cattle fed with diets different for Ca/P ratio and moisture content.

The urolithiasis is a multifactorial disease, encouraged by high concentrate, low roughage, low Ca:P ratio, high magnesium diets and alkaline urine. Alterations in parameters could be used as reference values for early recognition of a renal dysfunction. To verify the importance of dietary electrolytes modification we analyzed the electrolytes and their fractional excretion as a predictive parameters of renal failure. Sixty eight calves, divided into two groups, were kept under the same feeding condition in the first two period, called 1 and 2 period. At period 3 to the animals were administered two different kind of food, with different moisture percentage and Ca:P ratio. Urine samples were collected and the fractional excretion were calculated for urea (%Cr/Urea), Ca (% Cr/Ca), P(%Cr/P), Mg(%Cr/Mg), K(%Cr/Mg), Cl(%Cr/Cl). Two way repeated measure analysis of variance (ANOVA) was applied to every parameter within “group A” and “group B” to determine significant differences. The factors were period and feed. The statistical analysis showed a significant effect of “period” on the following parameters: for the “group A” specific gravity; pH; %Cr/P; %Cr/Ca. For the “group B”: specific gravity; pH; %Cr/P; %Cr/Cl; %Cr/Mg. The only parameter that showed a significance associated to food is %Cr/Mg, an important predictive factor for pathogenesis of urolithiasis, because an overload of Mg intake can results to an overflow in urine. The fractional excretion of P had a constant diminution in the 2nd and 3rd period in the D diet. Particularly in our research the variation observed for % Cr/Mg and %Cr/P is indicative of an alteration in the renal excretion.