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 U.S. and peas from Canada.

Two experiments were conducted to test the hypothesis that particle size of field peas and location where peas are grown do not affect apparent total tract digestibility (ATTD) of nutrients and gross energy (GE), 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, three sources of field peas were used. One source was obtained from the U.S., and two sources were obtained from Canada (i.e., Canada 1, Canada 2). The U.S. field peas were ground to 678, 457, or 265 µm, whereas the two sources of Canadian peas were ground to 411 and 415 µm. Therefore, five 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 five 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 Exp. 1, an N-free diet was also used to calculate basal endogenous losses of AA and CP, but in Exp. 2, no N-free diet was used. In Exp. 1, seven barrows (initial body weight = 60.6 ± 2.1 kg) that had a T-cannula installed in the distal ileum were allotted to a 7 × 7 Latin square design with seven diets and seven periods. In Exp. 2, twenty-four pigs (initial body weight = 30.8 ± 1.0 kg) were housed in six calorimeter chambers with four pigs per chamber. The six chambers were allotted to one of the six diets using a 6 × 6 Latin square design with six consecutive periods of 15 d. Results of Exp. 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 µm to 457 or 265 µm. Results of Exp. 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 the particle size was reduced from 678 µm to 457 or 265 µm. In conclusion, field peas grown in Canada or the U.S. have the same nutritional value, but starch digestibility and NE increase if the particle size of field peas is reduced.

Influence of particle size and origin of field peas on apparent ileal digestibility of starch and amino acids and standardized ileal digestibility of amino acids when fed to growing pigs.

The objective was to test the hypothesis that particle size and origin of field peas influence the apparent ileal digestibility (AID) of starch, crude protein (CP), and amino acids (AA) and the standardized ileal digestibility (SID) of AA. Three sources of field peas were procured. One source was from the United States and two sources were from Canada. The U.S. source and one of the sources from Canada (i.e., Canada 1) were each divided into two batches and ground to achieve a target particle size of 250 or 450 µm, whereas the other source from Canada (i.e., Canada 2) was only ground to a target particle size of 250 µm. Each batch of field peas was included in one diet as the only source of AA. An N-free diet was used to determine the basal endogenous losses of CP and AA. Six barrows (initial weight: 50.5 kg; SD = 3.7) that had a T-cannula installed in the distal ileum were randomly allotted to a 6 × 6 Latin square design with six diets and six 7-d periods. Ileal digesta from pigs were collected for 2 d after 5 d of adaptation. Data were analyzed using a statistical model that included batch of field peas as the fixed effect and animal and period as the random effects. Contrast statements were used to analyze the effects of particle size, origin, and the interaction between particle size and origin. Results indicated that the AID of starch was increased by reducing the particle size in the U.S. source of field peas, but that was not the case for the Canada 1 source (interaction; P < 0.001). Particle size did not influence the AID of CP or AA, but the Canada 2 source of field peas had greater (P < 0.05) AID of Trp, Ala, Cys, Gly, and Tyr than the field peas from the United States. The SID of CP and AA was also not affected by the particle size of field peas. The SID of CP and Trp was greater (P < 0.05), and the SID of His, Ile, and Thr tended (P < 0.10) to be greater in the Canada 2 source compared with the U.S. source, but no differences between the two Canada sources were observed. In conclusion, a few differences in SID of AA between field peas produced in the United States and peas produced in Canada were observed, but there was no effect on SID of AA of reducing the particle size of field peas from 450 to 250 µm, whereas the AID of starch increased by reducing the particle size only in the field peas from the United States.