Field peas are an excellent substitute for corn and soybean meal in swine diets. Inclusion rates up to 30% have shown no difference in average daily gain or feed efficiency. There is a tendency for slightly higher daily intake with field pea diets probably attributable to a higher fiber content of field peas. The limiting factor for including field peas in swine diets is the inability of cropping systems including field peas to economically compete with the current corn-soybean rotation in Iowa. There may be times when swine producers can purchase field peas on the open market and formulate rations that are a lower cost than the standard corn-soybean meal diet.
The typical Iowa swine farmer raises about 5000 head of hogs as well as corn and soybeans. In order to use soybeans as a protein source for the swine it is necessary to process the soybeans. Field peas have been grown successfully by farmers in other states and countries and used as a substitute for soybean meal. Inputs which require no processing, grown and used on the farm have generally improved farm profits. The feasibility of growing field peas in Southeast Iowa will be completed. Double cropped field peas will be evaluated for disease, insect susceptibility, yield and nutrition attributes and the economics compared to the standard corn-soybean rotation.
Small scale Iowa State University (ISU) replicated research plots as well as field scale cooperator plots will be set up to evaluate variety selection, time of planting, harvesting techniques, and pest management of field peas. Feeding trials will evaluate the economical inclusion rates of field peas into swine rations. Economic evaluation based on net return per acre, comparing field peas in a double-crop production system compared to the control which for this study is the current corn/soybean rotation with the purchase of soybean meal from off farm commercial sources. The second part of the evaluation will be the economic return to the producer feeding field peas compared to the control. Evaluation will be based on performance of the swine comparing health, cost/lb of gain, average daily gain, and feed efficiency.
In the short term, crop producers in Southeast Iowa will increase their knowledge of how field peas can fit into their crop rotational system, including information on variety selection, time of planting, harvesting techniques, and pest management. Pork producers will learn that field peas raised in the Midwest provide an excellent source of protein and energy for use in swine diets.
Intermediate term outcomes will be an increase in the profitability of crop and swine producers. Profits will also become more sustainable by introducing two new crops into the rotation. At current prices, the net profit from the wheat/field pea crop has the potential to be more than the net profit provided by either corn or soybeans. Swine producers will have an alternative protein/energy source for swine diets if soybean meal costs become prohibitive due to increased soybean pest problems, including soybean rust. Unlike soybeans, field peas do not have to be processed, so pork producers could grow and feed peas without them ever leaving the farm.
A long term outcome will be the widespread adoption of the new cropping system and the use of peas in swine rations throughout the Midwest, increasing the sustainability of agriculture.
Small Plots at the SE IA Research &amp; Demonstration Farm – Crawfordsville
The trial consisted of three crop rotations that were established in 2005 and were continued through 2008. One of the crop rotations included field peas double cropped after winter wheat and another rotation included soybean or milo double cropped after field peas. These rotations were compared to the standard corn-soybean rotation. The three crop rotations were; 1) corn-soybean, 2) corn-field peas/soybean (milo), and 3) corn-soybean-winter wheat/field peas. In 2007, the double cropped soybeans were replaced with two double cropped milo varieties. Each crop in each rotation was grown in every year of the trial.
Two field pea varieties were grown in rotation 2, and three field pea varieties were used in rotation 3 until 2008 when 1 variety was used. In rotation 3, three planting dates were used in 2005, two in 2006, and 1 in 2007 &amp; 2008. All treatments were replicated 4 times in a randomized complete block design. All plots were 20 feet wide by 40 feet long and were machine harvested for yield. Tillage was performed prior to planting all crops except the double cropped field peas after wheat. Appropriate fertilizer and pest management practices were used for each rotation. Spring planted field peas were desiccated with paraquat one week prior to harvest. Plant stand evaluations were made of all crops in all years.
Separate trials investigated seeding winter peas in the falls of 2005 and 2006, and using peas as a nurse crop for red clover in 2008.
A field pea-triticale intercropping trial was conducted investigating 3 seeding ratios of the pea/triticale mixture to a pure stand of field peas and triticale. The crop was seeded on tilled ground on April 4 and machine harvested for yield in late July. Plots were all 50 foot by 20 foot and arranged in a randomized complete block design with 4 replications. The five treatments were 1) triticale only seeded at 150 lb/A, 2) field peas only seeded at 180 lb/A, 3) triticale at 100 lb/A and field peas at 135 lb/A, 4) triticale at 75 lb/A and field pea at 180 lb/A, and 5) triticale at 150 lb/A and field pea at 90 lb/A. The triticale only treatment received a nitrogen application of 50 lb/A and the field pea only treatment received a paraquat application prior to harvest because of weed growth. Plant stand evaluations were made and grain samples were analyzed for nutritional content.
Large Field Trials with Farmer Cooperators
Seventy acres of spring planted field peas followed by double cropped soybeans were planted in Washington County. Two pea varieties were planted in a randomized block design on March 14. Peas were machine harvested on June 29 and 2 varieties of soybeans planted on July 1. Soybeans were harvested on October 18. Winter wheat was planted on 42 of the acres on October 25. The peas were used in swine feeding trials.
Two varieties of peas were planted in a randomized complete block design with 2 replications in late July following a winter wheat harvest in Washington and Johnson County. Fifteen acres were planted in each county. Plant stand evaluations were made and the peas were machine harvested. Peas were utilized in the swine feeding trials.
Three pea varieties were planted in randomized block design with 3 replications in mid-July following the harvest of the 42 winter wheat acres in Washington County. Plant stand evaluations were made and the peas were machine harvested for yield. Additional 20-acre trials were conducted in Johnson &amp; Iowa Counties, but peas were not harvested because of poor yields.
Three pea varieties were planted in a randomized block design with 3 replications in early April in Washington and Iowa County. Soybeans were planted in early July following the harvest of the peas in the Iowa County trial, and milo was planted following the pea harvest in Washington County. Both trials were 20 acres. All crops were machine harvested for yield and plant stand evaluations of all crops were made.
A 20-acre trial was conducted in a Washington County and Iowa County field to investigate double-cropped milo planted after field peas. Two varieties of field peas were planted in a randomized block design in each field in late April in both fields. Peas were machine harvested for yield in July and milo planted in the Iowa County field. Milo was not planted in the Washington County field because of weather delays. Plant stand evaluations were made in each trial.
An organic farmer investigated using peas as a nurse crop for establishing red clover in a 30-acre trial in Marion County. Two varieties of peas were planted in a randomized complete block design with 2 replications with a red clover seeding in late March. Peas were machine harvested for yield in July and plant stand evaluations made.
An organic farmer investigated using peas as a nurse crop for establishing red clover and alfalfa in Marion County. Peas were seeded with red clover in one 20-acre field and with alfalfa in a separate 20-acre field on April 15. Peas were machine harvested for yield in July and plant stand evaluations were made for all crops.
A farmer in Jones County interseeded field peas with triticale in a 15-acre field on March 28. Two seeding rates were investigated. One area was no-till drilled into soybean ground and another area no-till drilled into corn ground. Plant stand evaluations were made and the pea/triticale crop was machine harvested for yield in July. A grain sample was analyzed for feeding quality.
Large Feeding Trials with Farmer Cooperator – Keota, IA
A 1,200 head completely slotted floor grow-finish barn was utilized for 2 feeding trials. This facility consists of six rooms with each room holding two-hundred head. Each room is segregated and feed is supplied from one bin per room. Eight pens hold twenty five pigs per room. Each pen contains one Crystal Springs shelf wet/dry feeder. Feed was fed ad libitum and water was available at all times.
Pigs entered the barn from a single source farrowing farm and completed an on-farm eight week nursery program. Pigs were fed a standard corn-soybean meal based nursery diet for the first eight weeks until approximately 75 pounds. At eight weeks, pigs were moved to the finishing barn where they were weighed and began their respective treatment diet. Pigs were randomly allotted to rooms by weight. Pigs were split sexed with barrows and gilts being evenly divided for each replication. Each trial consisted of three treatments with two rooms per treatment (replications). Feed allotment will be on a room basis. After two weeks on the diet, pigs were reweighed to calculate any acclimation period to the new diet. Rations were balanced for caloric intake. Pigs were weighed at the end of the trial and feed intake calculated. Feed efficiency and average daily gain was calculated for each ration.
The first feeding trial was conducted the fall/winter of 2005-06 to investigate feeding rations containing 2 different field pea varieties. The treatments were 1) standard corn-soybean meal ration, 2) Eclipse pea variety at inclusion rate of 600 lbs/ton (30%), and 3) WFP 0097 pea variety at inclusion rate of 600 lbs/ton (30%).
A second feeding trial was conducted in the fall/winter of 2006-07 to investigate feeding rations at 2 different field pea inclusion rates. The treatments were 1) standard corn-soybean meal ration, 2) a low level field pea inclusion rate of 15% or 300 lbs/ton, and 3) a high level field pea inclusion rate of 30% or 600 lbs/ton. The high inclusion rate replaced almost all of the soybean meal in the ration.
Small Feeding Trial at the ISU Swine Nutrition Farm – Ames
This trial used rations containing Iowa grown field peas planted either in the spring, planted in the summer after winter wheat, or winter peas planted in the fall.
Peas. Field peas (winter, spring, and summer types) grown in southeast Iowa during 2005 and 2006 were sampled and analyzed for nutrient content.
Diets. The four diets were: 1) winter pea 30% of the total diet (by weight), 2) summer pea 30% of the total diet (by weight), 3) spring pea 30% of the total diet (by weight), 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 (Table 1). In the winter and summer pea diets crystalline lysine, tryptophan and threonine were added. In spring pea diet only crystalline tryptophan and threonine were added. The control diet had no crystalline amino acids added. All the diets were formulated to meet or exceed NRC nutrient recommendations for finishing pigs. Prior to mixing the diets, the grains were ground with a hammer mill using a 4.8-mm screen and presented in meal form.
Animals and Facilities. Finishing pigs, barrows (n = 64), offspring of PIC 336 terminal line bred to PIC Cambrough 227 sows all from the same farm were used in the experiment. A pen of four pigs composed an experimental unit. Pens were randomly allotted to one of the four treatment diets. Pig body weight and ancestry were equalized across the treatments. In each pen, a two-hole feeder and a nipple water drinker were installed. The pens were 1.8 m &#215; 2.7 m with a half concrete slatted floor. There were four replicate pens per treatment group. The pigs were housed in an environmentally- controlled building at the ISU Swine Nutrition Farm, Ames, IA.
Prior to the start of the experiment, all pigs were fed corn-soybean meal grower diets as a large group. The pigs started on the experiment after attaining body weight of approximately 80 kg and were fed the experimental diet for 39 d. Pigs were weighed individually at the start, at 14-d interval, and at the end of the experiment. The feed was weighed before it was placed in the feeders. The pigs had ad libitum access to feed, however the feeders were adjusted regularly to minimize wastage. On the final day of the experiment, the feed that was left in the feeders was weighed and feed disappearance from each pen was calculated.
Average daily feed intake (ADFI) was calculated for each pen and treatment group. ADFI = feed disappearance divided by the number of pigs per pen divided Iowa State University, Southeast Research and Demonstration Farm ISRF07-34 by the number of days on the experiment. Pig body gain (BG) and average daily gain (ADG) was calculated for each pen and subsequently for each treatment group. BG = start weight minus end weight. ADG = BG divided by number of days on experiment. Feed:Gain ratio (F:G) was calculated for each pen. FG = ADFI divided by ADG.
Scanning. At final weighing, each pig was scanned by a certified technician using an Aloka 500-V SSD ultrasound machine fitted with a 3.5-MHz, 12.5cm linear array transducer. A sound-transmitting guide placed on the pig’s back was used to collect image measurements off-midline for BF and LMA at the tenth rib. Vegetable oil was used to provide better conductivity between the skin and the probe. The ultrasonic measurements were used to determine fat-free lean weight of the live pigs (FF lean). The FF lean weight divided by the carcass weight = FF lean percentage (FFL%).
Statistical analysis. Data were analyzed using the PROC MIXED procedure of SAS. CLASS statement was treatment and pen. The pen was the experimental unit for performance data. Data for carcass leanness evaluation was also pooled within pen. The model contained treatment, ADFI, ADG, BF, and LMA. The LSMEANS statement and the PDIFF option were used to separate the means. To test significance, an alpha value of P &lt; 0.10 was used in the analyses.
A double cropping system utilizing spring planted field peas followed by soybeans was successful in 2005, with pea yields of 40-50 bu/A and double cropped soybean yields of greater than 20 bu/A in both field scale trials and small plot research. Yields of both crops were less in 2006, probably partly due to later planting dates in 2006 and to unusually warm weather in late May when the peas were flowering and setting pods. Yields were better in 2007 and 2008, although not as high as 2005 yields, perhaps partly due to excess spring rainfall. A winter pea variety planted in the fall of 2005 at the SE Iowa Research &amp; Demonstration Farm yielded slightly better than the spring pea varieties, but did not mature any sooner. A different winter pea variety planted on two planting dates in the fall of 2006 suffered severe winterkill and was not harvested.
One cooperator experimented with double-cropped milo after spring planted peas in 2006 and achieved milo yields of greater than 60 bu/A, even with a July 10 milo planting date. Based on this success and the low yields of double cropped soybeans, the double cropped soybeans were replaced with double cropped milo in 2007. Yields of double cropped milo planted on July 3 were about 90 bu/A at the research farm in 2007. Milo yields were about half of this in 2008, probably due to the later planting date of July 15 due to the wet spring. The double cropped milo was not planted until August 1 in the large field near Amana in 2007, so little grain was harvested, but the forage was utilized for cattle feed.
The double cropping system of winter wheat followed by summer planted peas has not been successful in any year. Although winter wheat yields were good in all years, the best field pea yield achieved was 19 bu/A with a late July planting date of the variety “Admiral” in small plots in 2005. Additional details of the 2005 results is attached or can be found at http://www.ag.iastate.edu/farms/05reports/se/DoubleCroppedField.pdf. Pea yields in field scale plots have generally been less than 10 bu/A. Summer planted peas were not worth harvesting on the research farm in 2007 or 2008 and no large fields were planted in 2007 or 2008. A summary of the results from the 2005-2008 research farm trials is attached or can be seen at http://www.ag.iastate.edu/farms/08reports/Southeast/DoubleCroppedFieldPea.pdf.
In 2007 and 2008, organic farmers investigated whether peas could be used as a nurse crop for establishing alfalfa and red clover. In 2007, a late freeze resulted in close to 100% kill of the red clover seeded with peas. Pea yields were fairly poor (18 bu/A) partly due to poor plant stands and lack of weed control. In 2008, the very wet spring resulted in the seedings being delayed until mid-April, which resulted in poor pea yields (17 bu/A), although alfalfa and red clover stands were acceptable.
In 2009 intercropping of field peas and triticale was investigated in small plots on the research farm and in one farmer’s field. Seeding ratios of 1:2, 1:1, and 2:1 of triticale to peas was investigated at the research farm and a 1:1 ratio was investigated in the farmer’s field. In general yields were poor in both the small plots and farmer’s field, probably because of a few very hot days in mid June that affected the flowering of both crops. The highest yield was with the 1:2 seeding ratio of triticale to peas, which yielded 27 bu/A.
Analysis of Pea Rations
Fairly extensive testing of field peas was done to give a basic understanding of nutritional levels. The Iowa peas were about 86% dry matter (14% moisture), which is a level that will store well. Crude fat averaged about 2%, although the 2005 spring varieties were less than 1%. Crude fiber was 5 to 6%. Ash was about 3% and crude protein averaged 20%. Nutrient analysis of field peas were taken on most plots with some reported in the attached document or found inline at: http://www.ans.iastate.edu/report/air/2007pdf/R2226.pdf
Field peas are a good source of lysine (about 1.54%), which is commonly the first limiting amino acid in pig diets. Unfortunately, peas are low in methionine and tryptophan (0.20%). Digestibility of these amino acids is lower in peas than in soybean meal. It may be advisable to add synthetic methionine and tryptophan to swine diets containing high levels of peas. Threonine average 0.74% in the winter, summer, and spring peas averaged about 0.74%. The amino acid levels in the Iowa-grown peas were similar to NRC table values. Field peas are low in fat compared with corn and contain twice as much fiber as corn. Therefore, peas are lower in energy than corn.
Large Scale Feeding Trials
The first feeding trial was conducted the fall/winter of 2005-06 involving a 1200 head finishing site with two replications of each treatment – 1) corn-soy, 2) Eclipse (variety) 300 lbs/ton field pea inclusion, and 3) WFP 0097(variety) 300 lb/ton field pea inclusion. Due to an outbreak of Circovirus within the site only one replication of each treatment was used in the final analysis. Performance of pigs on all diets was affected by disease outbreak but field pea and corn-soy diets showed no difference in average daily gain (ADG), which averaged 2 lbs/day. Rations were balanced for caloric intake. Excellent results were obtained from feeding field peas. The feed efficiency of the WFP 0097 variety of field peas (2.26) showed a statistical improvement over the other two diets.
The second large scale feeding trial involving a 1200 head finishing site with two replications of each treatment – 1) corn-soy, 2) a low level field pea inclusion 15% or 300 lbs/ton , and 3) a high level 30% or 600 lbs field peas per ton. There were no serious health issues with pigs during the experiment period. In this feed trial there was an issue involving the feed line to the second replication of higher inclusion pea ration so that data was discounted. The higher inclusion rate of field peas was enough to replace almost all of the soybean meal which would normally be included. Performance was very similar with all three rations when feed line issue group was eliminated from statistics.
Small Feeding Trial at the ISU Swine Nutrition Farm – Ames
A feeding trial using market barrows comparing diets containing spring planted peas, summer planted peas, and winter peas with a standard corn/soy based diet was conducted at the ISU Swine Nutrition Research Farm, Ames, IA during the fall of 2006. All pigs were in good health during the experiment period. Initial body weights did not differ between dietary treatments, as part of the experimental design. There was no difference in final weight for pigs in the four treatment groups and no treatment effects on ADG across dietary treatments. The Adjusted Daily Feed Intake was influenced by dietary treatments. Pigs tended to consume less corn-soybean meal and spring pea diets than the winter and summer pea diets.
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. There was no adverse effect on growth rate or feed conversion among the treatment groups. The 30% field pea inclusion rate was enough to replace all the soybean meal and reduce the corn. In the diets containing peas, synthetic lysine, tryptophan and threonine were added to the pea diets to avoid deficiencies. Additional details of this feeding trial are attached or can be found at http://www.ag.iastate.edu/farms/07reports/Southeast/EffectsofFeeding.pdf.
The feeding trials indicate that swine producers can increase their profits by utilizing field peas in the ration, especially with today’s very high corn and soybean meal prices. However, a profitable cropping system utilizing field peas in Iowa is yet to be found.
Midwest crop and swine producers learned about the possibility of increasing their economic sustainability by utilizing double-cropped field peas in swine rations by seeing the many articles that have appeared in the press about the project. Area producers learned that although there is an economic advantage to including peas in swine rations, they cannot be economically grown in a double cropping system in Iowa. Some producers are continuing to investigate other systems for including peas in their crop rotations, including seeding them as a nurse crop for establishing red clover and alfalfa, and intercropping them with a small grain. Swine producers closer to an available pea market are investigating the economics of purchasing peas to include in their
The feeding trials indicate that swine producers can increase their profits by utilizing field peas in the ration, especially with today’s very high corn and soybean meal (SBM) prices. A simple financial formula which producers can use when determining whether field peas should be used in their rations is: (corn price $/bu X 420 lbs/56 + SBM price $/ton X 180 lbs/2000)/10 = price which can be paid for field peas. This would be a 30% inclusion rate of field peas replacing corn and soybean meal in the ration. Inclusion rates this high showed no performance difference in any of the trials.
However, a profitable cropping system utilizing field peas in Iowa is yet to be found. The following table shows an economical analysis of different cropping systems grown over the trial period. Prices were adjusted back to the beginning year of the study to correct for large increases in both input costs as well as crop values. Government payments were ignored in all scenarios as they would be received no matter which crop was grown. Machinery costs were calculated using the ISU Custom Rate Survey. The field pea following wheat was eliminated from the analysis due to the very poor field pea yields.
The economic analysis of the cropping systems investigated on the SE Iowa Research &amp; Demonstration Farm shown in Table 1 indicates that none of the rotations including field peas can compete with the corn-soybean rotation even when using the best field pea, and double cropped soybean and milo yields obtained in the trials. The corn-soybean rotation showed an average net gain of $47.45/A in the two year rotation, compared to a net loss of $53.05 for the field pea followed by soybeans and a net gain of $3.11/A for the field peas followed by milo. Field peas grown alone would have a net loss of $59.60/A (when the $120 land charge is not split between 2 crops). Intercropping systems, such as using peas as a nurse crop for establishing a legume or seeding peas with a small grain for a feed crop, may be the best utilization for field peas in Iowa.
Although the practice of double-cropping field peas has not been adapted by Iowa farmers because of not being competitive with existing crop rotations, farmers are continuing to investigate the use of field peas in other cropping systems, and are looking into the possibility of purchasing peas for swine rations in parts of the state closer to pea producing regions.
Educational & Outreach Activities
Local producers learned about double cropped field peas at a field day held at the SE Iowa Research Farm near Crawfordsville in 2005 and on Amana Farms in the spring of 2006. Many articles about the project appeared in the mass media, including Iowa Farmer Today, Successful Farming, National Hog Farmer, and local newspapers. Presentations on the project results were presented at the Agronomy Society Association conference in Indianapolis and at the Integrated Crop Management Conference in Ames, IA in November of 2006. The Agronomy Society presentation is archived at http://a-c-s.confex.com/crops/2006am/techprogram/P22847.HTM.
A poster summarizing the results was presented at the Agronomy Society Association conference in New Orleans in 2007. Several copies of the poster were produced to be displayed at field days and other events.
Areas needing additional study
In order for double-cropped field peas to be an economical crop in Iowa there will need to be a great deal of improvements made in available varieties through plant breeding. Short season varieties that are more disease resistant and heat tolerant would increase the likelihood that double cropped field peas could be economical in Iowa. Raising field peas in Iowa currently is probably similar to raising soybeans in Iowa during the 1920’s and 1930’s with much work needing to be done in plant breeding. Further study also is needed to investigate the possibility of using peas as a nurse crop for establishing forages and in intercropping systems with small grains.