Barley and pea are common ingredients included in diets fed to non-ruminant animals in Canada. However, they are poor sources of phosphorus (P) because a large quantity of P is bound as phytate P. The objectives of this study were to determine the ileal digestibility of N, amino acids (AA) and total tract digestibility P and energy in growing pigs fed low-phytate barley (LPB), low-phytate field pea (LPP) or normal-phytate field pea (NPP) based diets and also determine the effect of phytase supplementation on nutrient digestibility in the LPP and NPP based diets. Five ileal cannulated barrows (43.6 ± 1.3 kg BW) were used in a 5x5 Latin square design experiment to determine the apparent (AID) and standardized (SID) ileal digestibility of N and AA in LPP, LPB and NPP and the apparent total tract digestibility (ATTD) of Ca, P and energy in diets containing these ingredients. In addition, the effects of phytase supplementation (500 FTU/kg) to diets containing LPP or NPP were determined. The experimental diets contained 869, 868 or 870 g/kg LPB, LPP and NPP, respectively, as the sole source of N. The phytate P contents were 0.4, 0.7 and 2.0 g/kg for LPB, LPP and NPP, respectively.. Titanium dioxide (3 g/kg) was used as an indigestible marker. Each experimental period lasted for 8 d; d 1-4 for adaptation, d 5-6 for urine and fecal collections, and d 7–8 for ileal digesta collection.
The ATTD of DM and GE was not different among diets and was not affected by phytase addition. The ATTD of Ca and P was higher (P<0.05) in LPB than in LPP and NPP diets. Supplementing the LPP and NPP diets with phytase increased (P<0.05) the ATTD of Ca and P. The AID of N and all AA except Met were higher (P<0.05) in LPP and NPP than in LPB, but no difference between LPP and NPP were observe. The LPB-based diet had similar energy and DM digestibility but lower AA, N and higher Ca and P digestibility compared to LPP and NPP. The LPP diets had higher Ca and P digestibility but similar AA, N, DM digestibility and ME value compared with NPP diets.
Therefore, less inorganic P can be included in diets formulated with LPP than NPP thus minimizing feed costs and reducing P excretion associated with the addition of inorganic P.
Kahindi, R.K., Thacker, P.A. and Nyachoti, C.M. 2015. Nutrient digestibility in diets containing low-phytate barley, low-phytate field pea and normal-phytate field pea, and the effects of microbial phytase on energy and nutrient digestibility in the low and normal-phytate field pea fed to pigs. Animal feed science and technology, 203; 79-87. doi:10.1016/j.anifeedsci.2015.02.009