Extruded-expeller soybean meal: An opportunity for Indian poultry Industry

Pashu Sandesh, 27 August 2021

Dr Sandeep Gupta Ph. D. (Animal Nutrition)

Soybean meal (SBM) has been recognized for decades as a major protein source for chickens. Although the poultry industry continues to face some difficulties in every quarter in which feed cost is one of the major constraints every year. This year, the main reason is rising SBM prices. There are many reasons for the increasing prices of SBM. In the last two years, the consumption of soybean seed has been increased tremendously in the food industry as well as extruded-expeller soymeal (EESBM). In a soybean-producing area like Indore, 80 to 100 extruder machines are used only for EESBM, the capacity of one machine is about 20 tons per day and about 6.5 lakh tons of EESBM are produced in a year from Indore only. And this is one of the reasons for an increase in soybean prices. Perhaps, India is not getting the benefit of EESBM because all production of EESBM is completely exporting since starting of this new process. Here the question is raised, can we use EESBM in poultry feed or can we replace soymeal or hipro soymeal full or partially? For getting answers to these questions, first, we would have to understand the nutritional values ​​of EESBM.

What is EESBM?

EESBM is the co-product of soybean seed produced by extruder and expeller process in which a dry extrusion process generates mechanical energy which is the only energy used to process the soybeans. This is the chemical-free process requires a certain temperature and pressure for the gelatinization of nutrients. Usually, 150-154 ⁰C temperature for 15-20 sec. require for gelatinization process and to deactivate antinutritional factors such as trypsin inhibitors, lectins, urease activities.

SBM Vs EESBM 

SBM is the primary protein source throughout the world for poultry and livestock diets (de Coca-Sinova et al., 2008). This most widely used protein supplement accounts for more than 50% of the world’s protein meals (Kohlmeier, 1990). Of the SBM produced in the United States, over 50% is fed to poultry (Loeffler et al., 2013). This plant protein is a good protein source due to its high protein content (44 or 48.5%; NRC, 1994) and consistent amino acid (AA) profile. Most tables on nutrient composition of ingredients (NRC, 1994; Institute National Recherche Agronomique, 2002; Fundación Española Desarrollo Nutrición Animal, 2003) include only 2 types of SBM based on the CP content: regular SBM with approximately 44-46% CP and dehulled SBM (Hipro soymeal) with approximately 48-50% CP. Usually, the amino acid (AA) profile and N digestibility reported is similar for the two SBM. In fact, the feed compound industry accepts that the digestible AA content of SBM per unit of protein is constant, irrespective of variables such as origin, genotype, processing, and storage conditions. However, the AA profile and nutritive value of available SBM might not be as uniform and predictable as it is believed (Irish and Balnave, 1993; Dudley-Cash, 1997; Douglas et al., 2000). In addition, the conditions applied during heat-processing (HP) of the beans add further variability to the quality of the resultant SBM (Waldroup et al., 1985; Parsons et al., 1991b). The nutritional value of SBM for poultry, however, is limited by several anti-nutritional factors (ANF) that interfere with feed intake and nutrient metabolism. A high content of protease inhibitors, especially trypsin inhibitors (TI), adversely affects protein digestibility and AA availability. Moreover, high amounts of protease inhibitors in a diet will cause pancreatic hypertrophy/hyperplasia, leading to poor growth performance (Applegarth et al., 1964; Rackis, 1965). Pancreatic hypertrophy is due to the stimulation of pancreatic secretions as the pancreas compensates for the increased amount of inhibitors within the intestinal tract. It was documented that heat processing counteracts most of these adverse effects (Liener, 1994; de Coca-Sinova et al., 2008). However, the methods of processing will have marked impacts on the nutritive value of soy products, as well as the overall digestibility of the diet. An excess of heat increases Maillard reactions between the amino group of the AA and the reducing sugars (such as glucose and galactose) and consequently, decreases energy and AA digestibility (Araba and Dale, 1990; Marsman et al., 1995; Qin et al., 1998). On the other hand, under processing may have negative effects because adequate processing is needed to remove the most ANF from soy products. Therefore, the conditions applied during heat processing are a compromise between the inactivation of ANF and the destruction of essential available nutrients. 

One of the effective heat treatments is extrusion technology, where the feed is exposed to a high temperature for a relatively short period of time with high pressure (Bj¨ork and Asp, 1983). The extrusion process may be a method to improve enzyme susceptibility and digestion of feed ingredients, resulting in an increased starch and protein digestion (Amornthewaphat et al., 2005). Bj¨ork et al. (1985) and Hancock and Behnke (2001) suggested that extrusion improved energy utilization and diet palatability.

Variations in AA digestibility coefficients and growth performance of animals fed on ESBM versus SBM were reported by different research groups (Woodworth et al., 2001; Lawerence et al., 2003; Opapeju et al., 2006; Baker and Stein, 2009). Different batches of SBM were obtained from a commercial market. The samples of SBM were analyzed for ANF contents, including TI and urease activities, according to the standard methods of the American Oil Chemists Society (1980). Among different samples, one SBM batch (solvent-extracted with hulls; origin Argentina) was selected because it seemed that this batch had not been properly processed based on its ANF content. Urease and TI activities of this SBM batch were 16,800 units/g and 0.23 Δ pH units, respectively (Table 1)(Jahanian et al., 2016). A part of this SBM was wet extruded at a high temperature (150 ± 2◦C) with high pressure for a short period of time (15 s) using a single screw (speed of 450 rpm, diameter of 10 cm), double conditioner extruder system (Amandus Kahl, Expander, OEE 32, GmbH & Co., KG, Germany). Standard temperature and duration time were 155◦C and 15 to 20 s for soy extrusion to maintain an optimum balance between degradation of ANF on the one hand and maintenance of some vitamins and bioavailability of essential AA on the other hand.

Economics to use EESBM in India:

EESBM is food grade co-product of soybean with almost similar digestible protein and amino acids and lesser ANF compared to SBM. Possibilities of inclusion of foreign material and adulteration are negligible in EESBM due to the dry extrusion process. A nutritionist can replace totally or partially SBM according to their requirement in the formulation.

Since July 2021 the export of EESBM has been stopped due to unknown reasons and manufacturers have enough stock of soybean seed at a higher price. Some of the manufacturers that have ready stock of EESBM that cannot store for a long period due to the fat content of EESBM. From October of every year, a new crop of soybean comes into the market which will reduce soybean prices up to 50 % of the current price and due to this most manufacturers must clear their stock until a new crop comes into the market. Hence, EESBM can fulfil the requirement of SBM at a very competitive price for the next two months. Although, 6-7 % higher price of EESBM than hipro SBM can absorb in the initial cost of poultry feed for a partial replacement.

“Every problem has a solution. You just have to be creative enough to find it.” Using partially EESBM can heal our wound by reducing feed cost to some extent in the current situation.

Compiled by: 

Dr Sandeep Gupta Ph. D. (Animal Nutrition), GMPE, IIM-I

For any query or advice: sandeep.gupta@dsandindia.com