True digestive utilization of phosphorus in pea (Pisum sativum) fed to growing pigs

An experiment was conducted to determine true digestive utilization of phosphorus (P) in common yellow field pea (Pisum sativum) by growing pigs. Eight barrows (average body weight = 31.9 kg) were fed 4 diets in a replicated 4 × 4 Latin square design. The 4 diets were a maize starch-based diet with 4 levels of P (1.1, 1.6, 2.3 or 2.8 g/kg dry matter; DM) from pea. All the 4 diets contained chromic oxide (4 g/kg) as an indigestible marker. Endogenous P outputs and true ileal and total tract P digestibility coefficients were estimated using the regression method. There was no effect (P>0.05) of dietary treatment on apparent total tract P digestibility. However, an increase in dietary level of P through dietary pea inclusion resulted in a quadratic response (P<0.05) in apparent ileal P digestibility such that the apparent ileal P digestibility was lower for the diet with 1.6 g/kg P than for the rest of the diets. Total P outputs in ileal digesta and feces increased linearly (P<0.05) as dietary P increased. An increase in dietary level of P resulted in significant linear relationships (P<0.05) between apparent ileal or total tract digestible P intakes (g/kg DM intake) and total P intakes (g/kg DM intake). Coefficient of true ileal and total tract P digestibilities in pea were estimated to be 0.53 and 0.51, respectively. The endogenous P losses associated with pea were estimated to be 0.25 g/kg DM intake in ileal digesta and 0.16 g/kg DM intake in feces. There were no differences (P>0.05) between ileal and fecal levels with regard to the true P digestibility and endogenous P output associated with pea. In conclusion, the true ileal or total tract digestibility values of P for pea were similar, and they could be used when formulating pig diets using the pea to match the pigs’ requirements and minimize excretion of P.