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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #229722
Title: EFFECTS OF INGREDIENTS AND EXTRUSION PARAMETERS ON AQUAFEEDS CONTAINING DDGS AND CASSAVA STARCH

Author
item KANNADHASON, S - SOUTH DAKOTA STATE UNIV
item MUTHUKUMARAPPAN, K - SOUTH DAKOTA STATE UNIV
item Rosentrater, Kurt

Submitted to: Journal of Aquaculture Feed Science and Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2008
Publication Date: 12/13/2008
Citation: Kannadhason, S., Muthukumarappan, K., Rosentrater, K.A. 2008. Effects of ingredients and extrusion parameters on aquafeeds containing ddgs and cassava starch. Journal of Aquaculture Feed Science and Nutrition. 1(1):6-21.

Interpretive Summary: Distillers dried grains with solubles (also known as DDGS) is a potential protein source for aquaculture feeds, but much work remains in order to effectively process this ingredient into a complete feed. Twenty-seven ingredient blends were formulated using three levels each of DDGS (20, 25, and 30% db), protein (30, 32.5, and 35% db), and feed moisture content (25, 35, and 45% db), along with cassava starch, soybean meal, fish meal, whey, vitamin and mineral mix to produce a balanced feed for tilapia. The ingredient blends were extruded using a laboratory-scale single screw extruder with varying screw speeds (100, 150, and 200 rpm) and extruder barrel temperatures (100, 125, and 150 oC). The resulting extrudates were subjected to extensive physical property analyses, including moisture content, unit density, bulk density, expansion ratio, sinking velocity, water absorption, water solubility, color (L*, a*, and b*), and pellet durability indices. Extruder parameters, including moisture content at the die, apparent viscosity, specific mechanical energy, mass flow rate, net torque, and die pressure were measured to quantify the extruder behavior during processing. All process settings used produced viable extrudates, but some were of better quality than others. For example, increasing the DDGS levels from 20 to 30% db, protein content from 30 to 35% db, feed moisture content from 25 to 45% db, and processing temperature from 100 to 150 oC decreased the PDI values by 7.50, 16.2, 17.2, and 16.6%, respectively. Increasing the feed moisture content from 25 to 45% db resulted in a substantial increase in SME values by 256.2%. On the other hand, increasing the screw speed from 100 to 200 rpm decreased the SME values by 33.7%. Results from this study show the importance of experimentally determining the effects of feed ingredients and process variables when developing aquafeeds from various materials. Even though this study has provided information about extrusion processing of DDGS with feed ingredients, work still remains in order to optimize aquafeeds from this protein source.

Technical Abstract: Twenty seven isocaloric (3.05 kcal/g) ingredient blends were factorially formulated using three levels each of DDGS (20, 25, and 30% db), protein (30, 32.5, and 35% db), and feed moisture content (25, 35, and 45% db), along with appropriate quantities of cassava starch, soybean meal, fish meal, whey, vitamin, and mineral mix to produce a balanced diet for tilapia feed. The ingredient blends were extruded using a laboratory-scale single screw extruder with varying screw speeds (100, 150, and 200 rpm) and extruder barrel temperatures (100, 125, and 150 oC). The resulting extrudates were subjected to extensive analyses of physical properties, which included moisture content, unit density, bulk density, expansion ratio, sinking velocity, water absorption, water solubility, color (L*, a*, and b*), and pellet durability indices. Several extruder parameters, including moisture content at the die, apparent viscosity, specific mechanical energy, mass flow rate, net torque, and die pressure were measured to quantify the extruder behavior during processing. All process settings used produced viable extrudates, but some were of better quality than others. For example, increasing the DDGS levels from 20 to 30% db, protein content from 30 to 35% db, feed moisture content from 25 to 45% db, and processing temperature from 100 to 150 oC significantly decreased the PDI values by 7.50, 16.2, 17.2, and 16.6%, respectively. Increasing the feed moisture content from 25 to 45% db resulted in a substantial increase in SME values by 256.2%. On the other hand, increasing the screw speed from 100 to 200 rpm significantly decreased the SME values by 33.7%. This study highlights the importance of experimentally determining the effects of feed ingredients and process variables when developing aquafeeds from novel materials.