EFFECTS OF VARIED DIETARY CALCIUM AND PHOSPHORUS ON RENAL-FUNCTION OFMALE BLUE DUIKER ANTELOPE

Sixteen adult male Blue Duikers (Cephalophus monticola bicolor) were f ed a basal diet with four levels of Ca and P for 4 months. Pretrial, 2 4-h urine clearance was studied in each Duiker while they consumed the herd diet (1.38% Ca/0.66% P) (The Pennsylvania State University (PSU) formulation). Pretrial, 24-h urine clearance values revealed no diffe rences (P>0.05) among treatment groups consuming the PSU diet. However , younger males did have higher serum P and lower serum and urine Ca c oncentrations (P<0.05). Posttrial renal function studies indicated age differences for [P]Plasma, [K]Urine, urine/plasma [K], and absolute e xcretion of K, which were higher in younger males, and free water clea rance and tubular P excretion, which were highest in older males. Rena l function was affected by the level of Ca and P in the diet. Glomerul ar filtration rate (GFR) and effective renal blood flow (ERBF) were lo wer (P<0.05), and fractional excretion (FE) of electrolytes and creati nine (Cr) were higher (P<0.05) in the T3 group (0.8% Ca/0.4% P), indic ating possible onset of renal dysfunction in these Duikers. Clearance of creatinine (C(Cr)) was negatively correlated with [Cr]Plasma, sugge sting tubular secretion of Cr increased during decreased renal functio n. Endogenous C(Cr) was not an accurate approximation of GFR, as deter mined by clearance of inulin (C(In)), in Blue Duiker under varying nut ritional conditions. FE of all electrolytes, as calculated by C(In), r egressed against the FE calculated from C(Cr), indicated a poor correl ation except for P. This suggests that FEp as measured by C(Cr) may be a useful index of early renal dysfunction in Blue Duiker. It appears that Blue Duiker have the ability to maximize P retention that may be available in limited quantity in the wild. The Ca/P ratio of 0.5:0.4% in the ration appears to be best suited for adult males.