Ferouz Y. Ayadi

Twin-Screw Extrusion Processing of Rainbow Trout (Oncorhynchus mykiss) Feeds Using Various Levels of Corn-Based Distillers Dried Grains with Solubles (DDGS)

ABSTRACT Increasing demand for seafood products and rising demand for fish meal for commercial fish feeds is driving the search for effective alternative protein sources. Twin-screw extrusion trials were conducted to study the production of nutritionally balanced feeds for rainbow trout fingerlings (Oncorhynchus mykiss). Six isocaloric (≈4.61 kcal/g) ingredient blends with a target protein content of >45% db were formulated with 0, 10, 20, 30, 40, and 50% distillers dried grains with solubles (DDGS) and other feed ingredients. The moisture contents of the diets were initially adjusted to 5–7% db, and then extruded at 250 rpm using dual 1.9 mm dies with varying amounts of steam (7.2–7.7 kg/hr) injected into the conditioner and water (4.3–6.5 kg/hr) into the extruder. Mass flow rates, moisture contents, and temperatures were measured during processing and moisture content, water activity, unit density, bulk density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water s...

Twin-Screw Extrusion Processing of Distillers Dried Grains with Solubles (DDGS)-Based Yellow Perch (Perca flavescens) Feeds

Increases in global aquaculture production, com- pounded with limited availabilities of fish meal for fish feed, has created the need for alternative protein sources. Twin- screw extrusion studies were performed to investigate the production of nutritionally balanced feeds for juvenile yellow perch (Perca flavescens). Five isocaloric (~3.06 kcal/g) ingredient blends, adjusted to a target protein content of 36.7% db, were formulated with 0%, 10%, 20%, 30%, and 40% distillers dried grains with solubles (DDGS) at an initial moisture content of 5-7%db, with appropriate amounts of fish meal, fish oil, whole wheat flour, corn gluten meal, and vitamin and mineral premixes. During processing, varying amounts of steam (6.9-9.7 kg/h) were injected into the conditioner and water (6.7-13.1 kg/h) into the extruder to modulate the cohesiveness of the final extrudates. Extrusion cooking was performed at 226-298 rpm using a 1.9 mm die. Mass flow rate and processing temperatures generally decreased with progressively higher DDGS content. Mois- ture content, water activity, unit density, bulk density, expansion ratio, compressive strength and modulus, pellet durability index, water stability, angle of repose, and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) among the blends were observed for color and bulk density for both the raw and extruded material, respectively, and for the unit density of the extruded product. There were also significant changes in brightness (L), redness (a), and yellowness (b) among the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low. On the other hand, all extruded diets resulted in very good water stability properties and nearly all blends achieved high pellet durability indices. In summary, each of the ingredient blends resulted in viable extrudates.

Single-screw extrusion modeling effects on extrusion processing parameters and physical properties of DDGS-based Nile tilapia (Oreochromis niloticus) feeds

A single-screw laboratory extruder was used to conduct an L18 (22 X 36) Taguchi fractional factorial study of aquafeed processing. The ingredients were based on a formulation for nutritionally-balanced Nile tilapia diets containing distillers dried grains with solubles (DDGS) and soybean meal as the main protein sources, in addition to constant amounts of corn flour, whey, and fish meal. The effects of three levels of DDGS (20, 30 and 40%), soybean meal (30, 40 and 50%), ingredient moisture content (20, 30 and 40% db), screw speed (100, 150 and 200 rpm), barrel temperatures (80-100-100°C, 80-120-120°C and 80-140-140°C), and die dimensions (L/D ratios of 5, 9 and 13), and two levels of screw configuration (compression ratios of 2:1 and 3:1) on extrudate physical properties (moisture content, water activity, color, bulk density, unit density, pellet durability index, expansion ratio, water stability, water absorption and solubility indices) and extruder processing parameters (resulting temperatures, extruder torque, die pressure, mass flow rate, and specific mechanical energy) were determined. Data from raw materials, processing conditions, and extrudate properties were used to develop surface response curves and equations. However, predominantly low R2 values (< 0.5) only permitted linear relationships between some independent parameters and response variables. Regarding main effects, die pressure significantly decreased with higher DDGS levels, moisture content, temperature, lower die L/D, and higher screw compression. Significant differences in color were caused by changes in DDGS levels and moisture content. Expansion ratio decreased significantly with higher moisture content and lower die L/D. In summary, DDGS, moisture content, die dimension, and the extruder had the biggest impact on most of the extrudate physical properties and processing conditions. Different combinations of these independent factors can be used to achieve desired extrudate physical properties and processing conditions.

Twin-Screw Extrusion Processing of Distillers Dried Grains with Solubles (DDGS)-Based Rainbow Trout (Oncorhynchus Mykiss) Feeds

The world’s increasing demand for seafood products has resulted in rising demands for fish meal for fish feed, which must be compensated for by searching for effective alternative protein sources. In this study, twin-screw extrusion trials were conducted to study the production of nutritionally-balanced feeds for rainbow trout fingerlings (Oncorhynchus mykiss). Six isocaloric (~ 4.61 kcal/g) ingredient blends with a similar protein content of 52.8% db were formulated with 0, 10, 20, 30, 40 and 50% distillers dried grains with solubles (DDGS) and other ingredients (i.e. fish meal, fish oil, whole wheat flour, corn gluten meal, and vitamin and mineral mix). The moisture contents of the diets were initially adjusted to 5-7% db, and then extruded at 250 rpm using dual dies of 1.9 mm die with varying amounts of steam (7.2-7.7 kg/h) injected into the conditioner and water (4.3-6.5 kg/h) into the extruder. The mass flow rates, moisture contents, and temperatures were measured during processing. Additionally, moisture content, water activity, unit density, bulk density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water stability, angle of repose, and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) among the blends were observed for color and bulk density for both the raw and extruded materials, respectively, and for the unit density and pellet durability index of the extruded products. There were also significant changes in redness (a) and yellowness (b), but only minor changes in brightness (L), among the final products when increasing the DDGS content of the blends. The compressive strength of the extrudates increased significantly with rising amounts of DDGS. Expansion ratio of all pellets was low. All extruded diets achieved very good water stability. Overall, each of the ingredient blends resulted in viable extrudates.

The effects of extrusion processing of distillers dried grains with solubles (DDGS)-based yellow perch (Perca flavescens) feeds

This study was conducted to investigate the production of balanced diets for juvenile yellow perch (Perca flavescens) feeds. Six isocaloric (~ 3.21 kcal/g), isonitrogenous (31.5% db) ingredient blends were formulated with 0, 10, 20, 30, 40, and 50% distillers dried grains with solubles (DDGS) at a feed moisture content of 60-65% db, with appropriate amounts of soybean meal, fish meal, vitamin and mineral mix. Extrusion cooking was performed using a laboratory-scale single screw extruder at a constant barrel temperature profile of 40oC-90oC-100oC, and a constant screw speed of 230 rpm (24.1 rad/s). During processing the mass flow rate was determined, which generally increased with progressively higher DDGS content. Additionally, moisture content, water activity, unit density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water stability and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) between the blends were observed for color and water activity of the raw and extruded material, and for the unit density of the extruded product. There were significant changes in brightness (L), redness (a) and yellowness (b) between the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low. On the other hand, all blends showed high pellet durability indices. Overall, each of the ingredient blends resulted in viable extrudates.

Twin-screw extrusion processing of distillers dried grains with solubles (DDGS)-based yellow perch (Perca flavescens) feeds

Due to tremendous increases in global aquaculture production, compounded with limited availabilities of fish meal for fish feed, the need for alternative protein sources cannot be disregarded. Toward that end, twin-screw extrusion studies were performed to investigate the production of nutritionally-balanced feeds for juvenile yellow perch (Perca flavescens). Five isocaloric (~ 3.06 kcal/g) ingredient blends, adjusted to a similar protein content of 36.7% db, were formulated with 0, 10, 20, 30, and 40% distillers dried grains with solubles (DDGS) at an initial moisture content of 5-7% db, with appropriate amounts of fish meal, fish oil, whole wheat flour, corn gluten meal, and vitamin and mineral mix. During processing, varying amounts of steam (6.9-9.7 kg/h) were injected into the conditioner and water (6.7-13.1 kg/h) into the extruder to modulate the cohesiveness of the final extrudates. Extrusion cooking was performed at 226-298 rpm using a 1.9 mm die. During processing, the mass flow rate and processing temperatures were determined (which generally decreased with progressively higher DDGS content). Additionally, moisture content, water activity, unit density, bulk density, expansion ratio, compressive strength and modulus, pellet durability index, water stability, angle of repose, and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) among the blends were observed for color and bulk density for both the raw and extruded material, respectively, and for the unit density of the extruded product. There were also significant changes in brightness (L), redness (a) and yellowness (b) among the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low. On the other hand, all extruded diets resulted in very good water stability properties and nearly all blends achieved high pellet durability indices. In summary, each of the ingredient blends resulted in viable extrudates.

Nitrification and denitrification activity in simulated beef cattle bedded manure packs

Abstract. Besides significant nitrogen (N) losses through ammonia, N can also be lost as nitrous oxide (N 2 O) via microbial incomplete nitrification and denitrification in the manure. We conducted lab-scale experiments to determine N 2 O, denitrification enzyme activity (DEA) and nitrification activity potential (NAP) in simulated beef cattle bedded manure packs (BP) under different conditions. Thirty-six BP were stored in humidity-controlled chambers at 10°C or 40°C, contained either corn stover or soybean stubble as the bedding material, and were 0-3, 3-6 and 6-9 week old. The DEA and NAP were measured weekly before material addition. Samples were taken from varying depths based on BP age, and incubated at room temperature with different reagents and distilled water. For DEA, subsamples were analyzed for both nitrite N and combined nitrite-nitrate N consumption over 56 h of incubation. For NAP, samples were measured for nitrite production over 144 h. Results showed that NAP (1.22 nmol g bedpack -1 h -1 , SE = 0.10) was much lower (1000 fold) than DEA (1.93 mmol g bedpack -1 h -1 , SE = 0.14). The DEA was similar throughout BP depth, whereas NAP was higher in BP middle section. Nitrifiers are slow growing microorganisms which may explain low NAP in BP, whereas denitrifiers are fast growing communities that can survive in aerobic and anaerobic environments. Surface gas fluxes were measured with static flux chambers (n=2 per treatment). Nitrous oxide concentrations were on average 0.50 ppm (SE = 0.03) with peak concentrations occurring as high pulses right after material addition. Nitrous oxide production was most likely caused by incomplete denitrification from pulse nitrate concentrations available in the dried bedding material. However, future research using specific inhibitors or stable N isotopes should verify which process, nitrification or denitrification, is responsible for N 2 O production.