Development of a Co-Extruded Canola Meal and Pea Starch Product to Replace Dietary Soybean Meal

Term: 3 years, beginning 2024
Status: Ongoing
Researcher(s): Rex Newkirk, U of S
SaskCanola Investment: $107,692
Total Project Cost: $402,690
Funding Partners: ADF, SPG

Objective

1.        Optimization of pelleting and extrusion parameters (co-extrusion of canola meal and pea starch).

2.        Determination of chemical composition and digestibility of a processed air classified pea starch/canola meal product.

3.        Determination of the impact of an air classified pea starch/canola meal product on poultry growth performance and feeding behavior.

4.        Determination of the effects of an air classified pea starch/canola meal product on egg production.

5.        Economic evaluation of the new processed product using least cost formulation modeling.

Project Description

Canola meal is a concentrated source of protein and has well-balanced amino acid composition especially methionine. Globally canola meal is the second most common source protein source used in animal diets with soybean meal being the most common. In western Canada, most of the soybean meal is imported and therefore costly. Canola meal has lower metabolizable energy than soybean meal limiting its use in some higher-density diets necessitating producers to use soybean meal despite its high cost. Canola meal contains elevated levels of fibre and antinutritive factors that reduce nutrient digestibility and concentration. Investigating ways to increase the energy level of solvent-extracted canola meal and reduced antinutritional factors is necessary to increase its market competitiveness, especially considering the rapid increase in production in Saskatchewan.

Canada is a significant producer of field peas and Saskatchewan accounts for approximately 51% of that production. There has been a major growth in the local fractionation of peas in response to a demand for high-value pea protein concentrate for the food and pet industry. When the seed is fractionated much of the product stream is air-classified pea starch. The production of starch has outstripped traditional markets for starch prompting the feed industry to consider using this energy-rich ingredient. However, classified pea is very finely ground (20-40 μm particle size) and therefore a product that is very difficult to handle in a standard feed mill. The applicant is currently studying the use of Air Classified Pea starch in Pig diets (ADF project # 20190261). The product results in excellent growth rate and feed conversion and is cost-effective as a feed ingredient, however, the fine particle size appears to negatively affect gut health (increases the occurrence and severity of gastric ulcers). In addition, the addition of pea starch impacts the handling properties of mixed diets in the feed mill. The fine particles interact physically with other more coarsely ground ingredients resulting in excessive bridging in grain handling systems.

Canola meal and air-classified pea starch complement each other nutritionally. Air-classified pea starch is high in starch, a good source of energy, and low in fibre complimenting the low energy, high fibre concentration of canola meal. In addition, canola meal contains high levels of sulfur amino acids (Methionine and Cysteine) which compliments air-classified pea starch which is deficient in these essential amino acids. The digestibility of both ingredients is lower than other common ingredients but processing methods such as high-temperature pelleting or co-extrusion can increase the digestibility of the starch and reduce antinutritional factors. Increasing the particle size and improving the handling by extrusion or high temperature pelleting could be a solution. Extrusion and pelleting are common feed thermal processes for producing ruminant, monogastric, pet food, and aquaculture feed. These processes increase particle size significantly. It is also well-established that heat treatment can reduce antinutritional factors and improve the digestibility of feeds and animal performance. Extrusion of canola meal significantly increases AME from 2242 to 2596 kcal/kg, and increases ileal digestibility of CP and Asp, Glu, Ser, Thr, and Try in broiler chickens. Similarly, the extrusion of peas reduces phytic P, NDF, ADF, and resistant starch, increases AMEn from 2161 to 2698 kcal/kg as well as ileal amino acid and CP digestibility. To our knowledge, no study investigated the effects of co-extrusion and pelleting of canola meal and pea starch products on the changes in nutrient composition, antinutritional factors levels, and particle sizes.

It is widely recognized that fine particles improve the exposure of the feed substrates to endogenous enzymes, leading to improved digestion and absorption of nutrients. However, the coarse physical structure is needed for the development and functionality of the gizzard and intestinal morphology, functionality, and gut microbiota profile in poultry. A researcher reviewed 15 studies on the effects of feed particle size on the relative weight of gastrointestinal segments. The gizzard weight is consistent with being lighter in the fine ground feed groups compared to coarse ground feed. A well-developed gizzard is needed for particle size reduction, nutrient degradation, and feed flow regulation and acts as the first line of pathogen defense. Subclinical gastrointestinal tract dysfunction may not be sensitive to be measured by commonly used growth performance parameters. However, meal frequency and length could be effective tools for examining the changes. There is limited research on the impact of fine (40μm) and enlarged particle size via thermal process of pea starch on gastrointestinal development, feeding behavior, and growth performance in broiler and layer.