Field peas are considered to be a relatively problem-free ingredient in poultry diets when peas are included at recommended levels. Field peas contain relatively low levels of trypsin inhibitors and spring-seeded cultivars contain less than one-half of the inhibitor levels in winter-seeded varieties. White-flowered cultivars are usually preferred for feeding to animals.

Protein content is influenced by a number of factors and amino acid content may be predicted using linear equations when crude protein (nitrogen) content is known.

Two extensive reviews of the literature on feeding peas to poultry are available (Castell et al., 1996; Fleury, 1998) and relatively little new information is available. As a result of these two reviews, information in this review has been typically limited to references containing publication dates of 1997 or more recent.

Introduction

The short digestive tract of poultry and the sequence in which ingesta is exposed to enzymatic processes and to mastication (reduction in particle size) are unique among the species discussed in this publication. The short transit time (short residence time in the digestive tract) places a premium on feedstuffs that are rapidly digested to permit absorption of the nutrients that are released.

The production of table eggs brings an emphasis on external and internal visual quality of the product. Examples of desirable visual characteristics for table eggs include color of the yolk and albumin, absence of inclusion bodies in the albumin, durable shells, and shells devoid of undesired pigmentation. When diets are fed to breeder hens, fertility of the egg becomes the major factor.

Pigmentation of body fat, skin, and shanks in broilers is a consideration that is influenced by the region where the product is consumed. Yellow pigmentation is preferred in the U.S. while other regions may prefer non-pigmented broiler products.

Skeletal soundness is desired in broilers and in turkeys to maintain value of the product. Turkeys, however, are often fed diets containing a number of ingredients that would not typically be present in the diets of broilers of laying hens. Nutritional management of broilers and turkeys may include moderate limitation of rate of gain during early growth to promote skeletal soundness. Early restriction of protein content of diets to permit subsequent compensatory growth is more widely practiced with turkeys than with broilers.

More is known about the nutritional requirements of poultry than other species. As a result, large breeding companies may provide information on recommended nutrient allowances or nutrient concentrations for birds of the various strains that they produce. If available, these nutritional recommendations should be consulted in formulating diets for poultry.

Laying hens

Yellow-, green-, and brown-seeded peas were fed at levels of 0%, 20%, 40% and 60% of the diet as substitutes for wheat and soybean meal by Igbasan and Gunter (1997a). When peas were fed at 20% of the diet, egg production, production of egg mass and feed conversion were increased relative to the wheat-soy control diet. At 40% of the diet, diets containing peas produced performance similar to that of the control diet. When diets contained 60% peas (total replacement of soybean meal), egg production, production of egg mass, and feed conversion were not equivalent to the control diet. Egg yolk color was improved as the level of peas was increased in these wheat-based diets. Shell quality was reduced by increasing levels of yellow- and brown-seeded peas but not by green-seeded peas. These authors concluded that yellow-, green-, or brown-seeded peas could be included at levels up to 40% of the diet without influencing production performance.

These authors (Igbasan and Gunter, 1997b) have reported that micronization, an infrared heat treatment, improved the feeding value of peas for laying hens but that dehulling or a crude pectinase enzyme supplement were not effective in improving hen performance. Perez-Maldonado et al (1999) reported that the viscosity of intestinal contents from hens fed diets containing 25% field peas was higher than when 25% faba beans or chickpeas were fed but lower than when the diets contained 25% lupins.

Broilers

Richter et al. (1999) reported that enzyme mixtures improved weight gain by 2.5% when broiler starter and finisher diets contained 29% peas. In contrast, Igbasan et al. (1997) reported that pectinase or a combination of pectinase and alpha-galactosidase enzymes did not significantly improve growth rate, feed intake, or feed conversion in a two-week study. Nimruzi (1998) reported that fig powder acted as a source of enzymes that reduced intestinal viscosity and improved digestibility when diets containing peas were fed to broilers.

Apparent ileal digestibility of protein from "coarse" peas was less than that of "fine" peas (70.2% vs 89.5%, respectively), although a decrease in protein digestibility between the ileum and excreta was noted for diets containing peas of the smaller particle size (Crevieu et al., 1997a). Crevieu et al. (1997b) detected small amounts of proteins that were resistant to hydrolysis but concluded that these represented only a small amount of the material present in the terminal ileum. Incorporation of dehulled peas at 70% of the diet resulted in acceptable performance of broilers (Daveby et al., 1998) and a response to alpha-galactosidase was observed with a small particle size produced by grinding. No response to the enzyme addition was obtained with the larger particle size of crushed peas.

Combining equal parts, by weight, of whole canola seeds with peas resulted in a linear reduction in weight gain of broilers (0 - 20 days or 20 - 40 days) when levels of 0%, 10%, 20%, or 30% were fed (Fasina and Canpbell, 1997b). This effect was presumably due to a curvilinear decrease in intake with increasing levels of the whole canola/pea blend. Pelleting the whole canola/pea blend improved performance (Fasina et al., 1997). Farrell et al. (1999) reported that steam pelleting of field peas improved growth rate and feed conversion of broilers and recommended an upper inclusion rate of 30% of the diet for broilers.

Turkeys

Czech workers (Mikulski et al., 1997) reported that 20 - 24% peas could be used to replace part of the soybean meal in diets for growing turkeys without adversely affecting performance, dressing percentage, or meat quality. These values are similar to the recommendations of Castell et al. (1996) of the use of peas as 25% of the diet for turkeys.

Practical experience

Field peas may be considered to be an energy source containing moderately high levels of crude protein rather than a protein feedstuff because the protein content approximates the protein requirement for most classes of poultry, except laying hens.

The use of high levels of field peas (20% - 30%) may result in a slight increase in viscosity of the digesta, but this increase is considerably lower than that associated with feeding several other feedstuffs. Some commercial enzyme supplements containing xylanases and beta-glucanases have been reported to reduce the viscosity of intestinal contents and increase protein digestibility when diets containing high levels of peas have been fed. At the highest levels of recommended use, litter in the poultry house may contain slightly more moisture than when conventional feedstuffs are fed without enzyme supplementation. Management practices may dictate whether or not this is a factor to be considered in individual poultry enterprises.

Levels Recommended in Diets for:

Layers

Diets for layers frequently contain up to 10% field peas as a slight decrease in the rate of lay (typically 2.5% to 3%) is observed when higher levels of peas are fed. Dietary levels of peas greater than 10% may be used when economic conditions favor the use of lower cost diets and the slight reduction in rate of lay results in comparable or reduced feed cost per dozen eggs produced. Under favorable economic conditions, layer diets may contain up to 30% peas (Castell et al., 1996).

Broilers

Diets for broilers often contain up to 30% field peas without effect on performance when equivalent nutrient concentrations are fed. However, an upper limit of 20% field peas in diets for broilers was suggested by Castell et al. (1996).

Turkeys

Diets for turkeys may contain higher levels of field peas as the birds mature and approach market weights. Little research is available on feeding field peas to turkeys. Birds weighing more than 12 to 16 pounds could receive diets containing at least 30% field peas when economic conditions are favorable, although Castell et al. (1996) suggested an upper limit of 25% of the diet. Upper limits of inclusion may be influenced by management conditions if moist droppings are encountered.

Variations in Energy Available Compared to Other species

The energy content of field peas for poultry, as for other ingredients, is lower than that of other species discussed in this publication because of the shorter length of the digestive tract and the more rapid rate of passage. As a point of reference, field peas contain available energy levels comparable to those of barley and cottonseed meal.

Variations in energy content have been attributed to color of inflorescence, color of seed, season of seeding (spring vs winter) and variety. The available literature suggests that white-flowered, yellow-seeded cultivars may be preferred, when available. Smooth-seeded varieties contain more digestible or metabolizable energy but less crude protein and amino acids than wrinkled-seeded varieties.

When field peas are fed in combination with feedstuffs containing restricted levels of energy, supplementation with fats or oils is suggested to increase the energy content of the diets and produce improved feed conversion ratios.

Amino Acid Supplementation

Field peas, like other legume seeds, are first-limiting in methionine and the sequence of limiting amino acids in diets containing peas will be influenced by the other ingredients in each diet. When formulating diets for poultry, the use of diet formulation software or a spreadsheet containing analytical information for all amino acids required by poultry is suggested to avoid neglecting or ignoring consideration of all amino acids required by poultry. In the absence of accurate analytical information for the field peas to be fed to poultry, standard reference tables (NRC, 1994) may be used to provide estimated analyses.

Processing

Feed intake in poultry is acutely influenced by particle size and the production of "fines" is to be avoided during grinding unless the diets are to be pelleted. Field peas are a low-fiber ingredient and should be easily ground in well-maintained equipment and at moisture levels where storage is not a problem. Grinding to an extremely small particle size is not economical and may lead to interference with feed intake due to buildup of material in the beak. Beak necrosis has been suggested to be one result of impaction of small particles in the beak.

Some reports have suggested that attention should be given in the feed mill when diets containing more that 20% field peas are pelleted. In contrast, formulations containing peas as the major source of energy and protein have been pelleted without difficulty (K.B. Koch, personal communication, May 11, 2001).

The experience of the pellet mill operator, operating conditions, and particle size of the ingredients may be factors in successful pelleting of diets containing peas.

References

Castell, A.G., W. Guenter, F.A. Igbasan, and R. Blair. 1996 Nutritive value of peas for nonruminant diets. Animal Feed Sci. Technol. 69(3 - 4):209 - 227.

Crevieu, I., B. Carre, A.M. Chagneau, J. Gueguen, and P. J. Melcion.1997a Effect of particle size of pea (Pisum sativum L.) Flours on the digestion of their proteins in the digestive tract of broilers. J. Sci. Food Agric. 75(2):217 - 226.

Crevieu, I., B. Carre, A.M. Chagneau, L. Quillien, J. Gueguen, and S. Berot. 1997b Identification of resistant pea (Pisum sativum L.) Proteins in the digegstive tract of chickens. J. Ag Food Chem 45(4):1295 - 1300.

Daveby, Y.D., A. Razdan, and P. Aman. 1998 Effect of particle size ans enzyme supplementation of diets based on dehulled peas on the nutritive value for broiler chickens. Animal Feed Sci. Technol. 74(3):229 - 239.

Farrell, D.J., R.A. Perez-Malondano, and P.F. Mannion. 1999 Optimum inclusion of field peas, faba beans, chick peas and sweet lupins in poultry diets. II. Broiler experiments. Brit Poultry Sci. 40(5):674 - 680.

Fasina, Y.O. and G.L. Campbell. 1997 Whole canola/pea and whole canola/meat blends in diets for broiler chickens. 2. Determination of optimum inclusion levels. Canad. J Animal Sci. 77(2):191 - 195.

Fasina, Y.O., G.L. Campbell, and R.T. Tyler. 1997 Whole canola/pea and whole canola/meat blends in diets for broiler chickens. 1. Evaluation of steam-pelleting or expansion processing. Canad. J. Animal Sci. 77(2):185 - 190.

Fleury, M.D. 1998 The use of peas in poultry diets. In: Research Summaries: Canola and Peas in Livestock Diets. Eds.: B. Stefananyshyn - Cote, M. Fleury, and L. Elwood. p. 8 - 23.

Igbassen, F.A. and W. Guenter. 1997a The influence of feeding yellow-, green-, and brown-seeded peas on production performance of laying hens. J. Sci Food Agric. 73(1) 120 - 128.

Igbassen, F.A. and W. Guenter 1997b The influence of micronization, dehulling, and enzyme supplementation on the nutritive value of peas for laying hens. Poultry Sci. 76(2):331 - 337.

Igbassen, F.A., W. Guenter, and B.A. Slominski.1997 The effect of pectinase and alpha-galactosidase supplementation on the nutritive value of peas for broilers.

Canad. J. Animal Sci. 77(3):537 - 539.Mikulski, D., A. Faruga, L. Kriz, and D. Klecker. 1997 The effect of thermal processing of faba beans, peas, and shelled grains on the results of raising turkeys. Zivocisna-Vyroba 42(2):72 - 81.

Nimruzi, R. 1998 The value of field peas and fig powder. World Poultry 14(3):20.

NRC Nutrient Requirements of Poultry, 9^th Ed. 1994. National Academy Press, Washington, D.C.

Perez-Malonado, R.A., P.F. Mannion, and D.J. Farrell. 1999. Optimum inclusion of field peas, faba beans, chick peas and sweet lupine in poultry diets. I. Chemical composition and layer experiments. Brit. Poultry Sci. 40(5):667 - 673.

Richter, G., M. Schurz, W.I. Ochrimenko, H. Kohler, R. Schubert, G. Flachowsky, R. Bitsch, and G. Jahreis. 1999 The effect of NSP-hydrolysing enzymes in diets of laying hens and broilers. Vitamine und Zusatzstoffe in der Ernahrung von Mensch und Tier: 7. Symposium Jena-Thuringen, Germany, p.
519 - 522.

EB-76, May 2002

• Introduction to Field Pea Blaine Schatz
• Field Pea in Beef Cattle Diets Vern Anderson
• Field Peas in Dairy Cattle Diets J.W. Schroeder
• Field Pea in Swine Diets Doug Landblom
• Field Pea in Sheep Diets G.P. Lardy, M.L. Bauer, E.R. Loe