The objective of this study was to investigate an alternative feedstuff, Iowa-grown field peas, for finishing pigs. Field peas (winter, spring, and summer types) grown in southeast Iowa during 2005 and 2006 were sampled and analyzed for nutrient content. Overall, the peas were 2.8% fat, 5.7% fiber, 3% ash, 19.3% protein, 1.5% lysine, 0.73% threonine 0.18% tryptophan, and 0.20% methionine. The spring peas were generally lower in fat and higher in essential amino acid content than the summer and winter peas. Finishing pigs, barrows (n = 64) were randomly assigned to pens with four pigs each. There were four replications per treatment group. Each pen was assigned one of the four diets. The four diets were: 1) winter pea 30% of the total diet (by weight), 2) summer pea 30%, 3) spring pea 30%, and 4) corn-soybean meal as the control. The three pea diets contained corn but no soybean meal. Each of the four diets had 0.64% lysine based on calculated analysis. Crystalline amino acids were added to the pea diets. The pigs started the experiment at 80 ± 2.5 kg live weight and were fed the experimental diets for 39 days. Pigs were weighed individually at the start, at 14-d intervals, and at the end of the experiment. At final weighing, backfat and loin muscle area was ultrasonically evaluated on each pig.

There was no difference in final pig weight (123 ± 3 kg) in the four treatment groups. There were no treatment effects on average daily gain (ADG) (P = 0.22) across dietary treatments. Average daily feed intake (ADFI) was influenced by dietary treatments (P < 0.10). Pigs tended to consume less corn-soybean meal and spring pea diets than the winter and summer pea diets, with ADFI of 4.0, 3.8, 3.5, and 3.4 kg/d for winter, summer, spring, and the control diets, respectively. Feed:Gain (F:G) was not different among the treatment groups. Pigs fed winter peas had greater (P < 0.10) backfat (BF) than pigs fed spring peas or the control diet. Pigs fed summer peas were intermediate in BF and did not differ from the other treatments. There were no differences between dietary treatments for loin muscle area (LMA), although the pigs fed spring peas had numerically smaller loin muscle areas. There were no differences in the overall fat-free lean values (P > 0.10). In this study, the results showed no decrease in performance of finishing pigs at the inclusion rate of 30% field peas in a corn-based diet. The 30% field pea inclusion rate was enough to replace all the soybean meal and reduce the amount of corn in the diet. In the diets containing peas, synthetic amino acids, lysine, tryptophan, and threonine were added in the pea diets to avoid deficiencies. Because of their chemical composition, agronomic characteristic, and easy on-farm feeding, field peas are a potential crop to consider for Iowa pork production. Results from this study indicate, Iowa-grown field peas at 30% rate can replace all of the soybean meal and part of the corn in diets for finishing pigs with no negative effects on performance.