Vegetal protein sources in poultry: peas and rapeseed

Vegetal protein sources

Protein sources are expensive, making it convenient to use the exact amount of these ingredients to avoid unnecessary production costs. These protein sources can have a plant or an animal origin. The former are, generally, more affordable than the latter. Besides, while some countries banned the use of animal protein sources for poultry feeds, there are no legal limitations regarding the use of vegetal sources.

Plant-based protein ingredients have a relatively high protein content, such as leguminous species. The most frequently used in soy (FAO 2013); in spite of this, due to its seldom available in some regions and its high price, producers look for cheaper alternatives such as peas (Pisum sativum Hortense) or rapeseed (Brassica napus and B. campestris).

Peas and rapeseed: What to consider when using these ingredients in the feed formula?

When peas and rapeseed are used as a protein source in poultry diets, two main factors need to be considered: the amino acid profile and the presence of antinutritional factor or ANFs.

Amino acid profile

As mentioned in previous articles (GVL 2021), it is vital to design the feed formulas based on the ideal protein, which means to consider the exact amounts of each amino acid of the ingredients instead of their crude protein content. This way, the formula can be better adjusted to the birds’ requirements.

The following table shows the amino acid profile of peas and rapeseed. Their profile varies depending on the procedures applied to these ingredients, and, generally, it improves after temperature treatments. That is because they contain thermolabile antinutritional factors, which are described below. Despite this fact, it is difficult to eliminate all ANFs, since high and long temperature treatments can also decrease the ingredients’ nutritional quality and lead to the formation of toxic compounds.

Antinutritional factors (ANFs)

ANFs are the second factor to consider, since they are substances that, whether by themselves or through their metabolites, decrease the availability of nutrients and impair health and performance results (Makkar 1993). The presence of these factors in ingredients such as peas and rapeseed can limit their inclusion in the feed.

ANFs concentration in higher in ingredients rapeseed and peas than in other protein-rich ingredients like soy and is a constant challenge for the intestinal health and welfare of birds.

Peas contain different ANFs (Vidal-Valverde et al. 2003):

  • Α-galactosides, sugars with low molecular weight that are fermented in the digestive tract causing gas accumulation, which impairs gut peristalsis, the digestion of other compounds and the obtention of energy. They also cause an increase of the secretion of water in the intestinal lumen, leading to the presence of wet feces (Martínez-Villaluenga, Frias, and Vidal-Valverde 2008).
  • Trypsin inhibitors inactivate the enzymes necessary for protein digestion (Fekadu Gemede 2014). These ANFs are partially denaturalized after the heat treatment and, because of it, processed peas have greater amino acid availability.
  • Phytates are phytic acid salts that act as metal ion scavengers. They negatively impact minerals’ availability like calcium, magnesium, copper or zinc (Fekadu Gemede 2014).

Rapeseed contains glucosinolates, which limit the inclusion of this ingredient in feed. Despite not being toxic by themselves, the enzyme myrosinase, present in grain or synthesized by microorganisms in the digestive tract, hydrolyzes it and forms toxic compounds. They worsen performance and can cause death by liver hemorrhages (Brand, Smith, and Hoffman 2007). Rapeseed contains erucic acid, too, a cardiotoxic compounds. That is why it is recommended to use Canadian varieties, also called 00 varieties, as they contain low amounts of these ANFs (<1% of erucic acid and <15 µmols/g of glucosinolates) (Blas et al. 2019).

Other ANFs of rapeseed that limit its use in monogastrics are lignin (fiber) and tannins. The latter bind proteins and reduce their availability. They are thermostable (Fekadu Gemede 2014).

Use of enzymes to counteract the negative effects of ANFs and improve the nutritional quality of peas and rapeseed

Enzymes are an effective solution to improve the efficiency of diets containing peas and rapeseed. Enzymes can inactivate and/or eliminate some ANFs, improving digestive processes and the availability of the nutrients affected by the presence of these factors (Goodarzi Boroojeni et al. 2017).

The most recommended enzymes are designed based on the diet’s composition and the needs of birds in each growing stage. If the diet contains peas, products with α-galactosidae and proteases such as subtilisin and phytases are recommended.

For rapeseed, the recommended enzymes are proteases that counteract tannins’ effects, and enzymes that degrade non-starch polysaccharides, like cellulase, glucanase and chitinase. In addition, temperature treatments are advisable in order to inactive myrosinase.

How can we help you?

In Global Vet’s Lab, we offer the feed formulation and analysis service to optimize feed composition and adjust it to the requirements of the target species, as well as to prevent problems derived from the inclusion of vegetal protein sources thanks to using the most suitable enzymes.

To use the service, please contact us through our webpage or email at


Blas, C. de, P. Carcía-Rebollar, M. Gorrachategui, and G.G. Mateos. 2019. Tablas FEDNA de composición y valor nutritivo de alimentos para la fabricación de piensos compuestos FEDNA (Fundación Española Para El Desarrollo de La Nutrición Animal). 4th ed. Madrid.

Brand, T. S., N. Smith, and L. C. Hoffman. 2007. “Anti-Nutritional Factors in Canola Produced in the Western and Southern Cape Areas of South Africa.” South African Journal of Animal Sciences 37(1): 45–50.

FAO. 2013. “Disponibilidad de Piensos y Nutrición de Aves de Corral En Países En Desarrollo Principales Ingredientes Utilizados En Las Formulaciones de Alimentos Para Aves de Corral.” Revisión Del Desarrollo Avícola: 3.

Fekadu Gemede, Habtamu. 2014. “Antinutritional Factors in Plant Foods: Potential Health Benefits and Adverse Effects.” International Journal of Nutrition and Food Sciences 3(4): 284.

Goodarzi Boroojeni, F. et al. 2017. “The Effects of Fermentation and Enzymatic Treatment of Pea on Nutrient Digestibility and Growth Performance of Broilers.” Animal 11(10): 1698–1707.

GVL. 2021. Uso de Aminoácidos En Dietas Para Pollos de Engorde. Constantí.

Makkar, H. P. S. 1993. “Antinutritional Factors in Foods for Livestock.” BSAP Occasional Publication 16(16): 69–85.

Martínez-Villaluenga, Cristina, Juana Frias, and Concepción Vidal-Valverde. 2008. “Alpha-Galactosides: Antinutritional Factors or Functional Ingredients?” Critical Reviews in Food Science and Nutrition 48(4): 301–16.

Vidal-Valverde, Concepción et al. 2003. “Assessment of Nutritional Compounds and Antinutritional Factors in Pea (Pisum Sativum) Seeds.” Journal of the Science of Food and Agriculture 83(4): 298–306.

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