Research: Feeding Peas to Poultry

Pea production on the Prairies has increased dramatically in recent years but the use of peas in poultry diets has been limited. One of the problems faced by producers and feed mills is the variability in the feeding value of this crop for poultry. Because of this variation, people are unsure of how birds will perform on pea-based rations and reluctant to include high levels of peas in poultry feed.

With the support of funding from Manitoba Egg Producers, Dr. Bill Guenter and Dr. Francis Igbasan at the University of Manitoba have conducted research that will allow producers and feed mills to better predict the feeding value of peas. In a series of trials at the university, these researchers investigated the effect of growing conditions, pea variety and seed colour on the feeding value of the protein and energy in peas.


Fertilizer, Crude Protein Content and Total Amino Acids

Growing conditions have a strong impact on the crude protein level in peas. In a trial at the University, peas ranging from 22% to 26% crude protein content on a dry matter basis were produced by varying the level of nitrogen fertilizer applied to the crop. As more fertilizer was applied to the fields, the arginine and non-essential amino acids in the peas also increased. These amino acids make up the majority of the amino acids found in the storage proteins in peas. Most of the essential amino acids such as lysine only increased slightly as crude protein level increased. Methionine, the most limiting amino acid in peas, did not increase at all. When formulating pea diets, the estimated methionine values should not be increased even when feeding peas that test high in crude protein content.

Effect of Variety and Seed Colour on Nutrient Content and Availability

Samples of twelve different varieties of peas (eight yellow seed, two green seed and two brown seed varieties) were collected. Each sample was tested for crude protein and total amino acids. The amino availability and nitgrogen corrected true metabolizable energy (T.M.E.n) content of each sample was measured using the precision-feeding technique with fasted, adult cockerels. The samples were not all grown in the same location and some of the variety differences could have been due to different growing conditions. The results of the survey are presented in Table 1.


Table 1. Crude Protein & Amino Acids in Twelve Pea Varieties



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The crude protein content of the peas varied considerably with pea variety but was not related to seed colour. The total lysine content was slightly higher in pea varieties containing high levels of crude protein but total sulphur amino acids did not vary noticeably from one variety to the next.

The availability of the lysine and total sulphur amino acids was noticeably depressed in the brown seed varieties (Carman and Sirius). These varieties contained much higher levels of tannins than any of the other varieties. Further research with one variety each of yellow, green and brown coloured peas (Impala, Radley and Sirius varieties) demonstrated that apparent protein digestibility was 75% and 73% for the yellow and green varieties respectively but only 60% for the brown variety. Because tannins interfere with protein digestibility, the availability of amino acids and protein digestibility in brown seeded varieties of peas should be discounted.

The average T.M.E.n value for the twelve varieties was 2920 kcal/kg d.m. and most varieties were in the 2800 to 3010 kcal/kg d.m. range. The Trump and Sirius varieties had very low T.M.E.n values (2720 and 2630 kcal/kg d.m. respectively). Unlike amino acid availability, the T.M.E.n was not strongly related to seed colour or tannin content of the peas. Further work was conducted with the Sirius variety and its apparent metabolizable energy and apparent starch digestibility were determined to be significantly lower than in other pea varieties. When formulating poultry rations, the energy values estimated for the peas should be altered according to the variety and not just the seed colour of the peas used.


Recommendations on Feeding Peas to Poultry

1) Young birds can be readily fed up to 20% peas in their diet. When feeding above this level, it is imperative to consider the protein content, seed colour and variety of the peas. If all of these factors are taken into consideration, it may be possible to include up to 40% peas in the feed and obtain results similar to those on wheat-soy bean diets.

2) Under research conditions, laying hens can be fed 40% peas and have the same performance as birds fed a wheat-soy diet. Above this level, egg production decreases, feed per dozen eggs increases and egg shells become thinner. Adding extra protein or amino sources to diets containing over 40% peas does not appear to improve bird performance. Including 20% or more peas in the feed will darken the yolks and yolk colour may not be acceptable to consumers on the Prairies. The production response of laying hens to different levels of peas in research at the university is displayed in Table 2 below. As a safe guideline for maintaining egg production, it is suggested that up to 30% peas can be included in rations used on commercial farms.


Table 2. Influence of Feeding Varying Levels of Peas on Egg Production, Feed Intake, Feed Conversion and Egg Size from 24 to 40 Weeks of Age