Reduction of particle size of field peas (Pisum sativum L.) increases net energy and digestibility of starch when fed to growing pigs, but there is no difference in nutritional value between peas from the United States and peas from Canada

Two experiments were conducted to test the hypotheses that particle size of field peas and location where peas are grown do not affect apparent total tract digestibility of nutrients and gross energy, digestible energy (DE), metabolizable energy (ME), and net energy (NE), apparent ileal digestibility (AID) of starch, or standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA). In both experiments, 3 sources of field peas were used. One source was obtained from the United States and 2 sources were obtained from Canada (i.e., Canada 1 and Canada 2). The U.S. field peas were ground to 678, 457, or 265 mu m, whereas the 2 sources of Canadian peas were ground to 411 and 415 mu m, respectively. Therefore, 5 batches of field peas were used in both experiments. A basal diet contained corn and soybean meal as the only source of energy, starch, and AA, and 5 diets containing corn and soybean meal and 50% of each source of field peas were also formulated. The ratio between corn and soybean meal was 1.92:1 in all diets. In experiment 1, an N-free diet was also used to calculate basal endogenous losses of AA and CP, but in experiment 2, no N-free diet was used. In experiment 1, 7 barrows (initial body weight = 60.6 +/- 2.1 kg) that had a T-cannula installed in the distal ileum were allotted to a 7 x 7 Latin square design with 7 diets and 7 periods. In experiment 2, 24 pigs (initial body weight = 30.8 +/- 1.0 kg) were housed in 6 calorimeter chambers with 4 pigs per chamber. The 6 chambers were allotted to one of the 6 diets using a 6 x 6 Latin square design with 6 consecutive periods of 15 d. Results of experiment 1 demonstrated that the SID of CP and AA was not influenced by the origin of the peas or by the particle size, but the AID of starch increased (linear, P < 0.001) as particle size was reduced from 678 to 457 or 265 <mu>m. Results of experiment 2 indicated that growing location did not affect concentrations of DE, ME, or NE of field peas, but concentrations of DE, ME, and NE increased (linear, P < 0.05) when particle size was reduced from 678 to 457 or 265 <mu>m. In conclusion, field peas grown in Canada or the United States have the same nutritional value, but starch digestibility and NE increase if the particle size of field peas is reduced.