Processing Sorghum for Feed Manufacturing

Post on June 22, 2026

Processing Sorghum for Feed Manufacturing

Carlos Campabadal, PhD, IGP Institute, Department of Grain and Food Science, Kansas State University

Sorghum is an important cereal grain used in livestock, poultry, aquaculture and pet food diets worldwide. It provides a valuable source of energy, and moderate protein levels typical of other cereal grains.

Typical Nutrient Composition (Dry Matter Basis)

Crude Protein: 9-13%
Starch: 65-75%
Crude Fat: 2-4%
Crude Fiber: 2-4%
Metabolizable Energy: Similar to 90-98% of corn depending on variety and processing

Tannin Considerations

Sorghum varieties that are free of condensed tannins, such as those produced in the United States are preferred for feed manufacturing. The absence of tannins improves protein digestibility, feed intake and animal performance.

Quality Control during Receiving and Storage

It's important to measure moisture content, foreign material, mold presence, insects, heat damage, test weight and mycotoxins. One advantage of sorghum is its hard endosperm, which generally makes it less susceptible to insect attacks than other cereal grains.

Storage Recommendations

• For short term storage, the recommended moisture content is ≤14 - 15%.
• For long-term storage (6+ months depending on weather and location) recommended moisture content is ≤13%.
• Maintain grain temperature below 28°C (82°F) or lower to avoid mold growth and insect activity, especially in warmer and humid locations.
• Grain silo floor or pressurized ducts should have opening for air flow movement smaller than 5/32 in to avoid kernels passing through.
• For aeration, use airflow rates between 0.1 cfm/bu (equal 0.1 m^3/min/MT) which is like the ones used for other cereal grains. Static pressure will be 10 to 20% higher compared to corn due to sorghum smaller size.

Grinding Sorghum

Grinding is the most critical processing step because sorghum kernels are harder than corn and have stronger starch-protein interactions.

Recommended Particle Sizes:
Broilers: 500-700 μm
Layers: 700-1,000 μm
Nursery pigs: 400-600 μm
Grow-finish swine: 500-700 μm
Dairy cattle: 800-1,500 μm
Beef feedlot cattle: 1,000-2,000 μm

Hammer Mill Screen Recommendations

The practical maximum screen size for sorghum is 5/32 inch (4.0 mm). Larger screens increase the risk of whole kernels passing through.

Recommended screen sizes:
3/32 in (2.4 mm): Very low risk
1/8 in (3.2 mm): Low risk
5/32 in (4.0 mm): Acceptable maximum
3/16 in (4.8 mm): Moderate risk
1/4 in (6.4 mm): High risk

To minimize whole kernels, maintain hammer tip speed above 16,000-18,000 ft/min (80-90 m/s), keep hammers with minimal wear, use adequate screen open area, avoid excessive feed rates and routinely inspect ground grain.

Conditioning And Pelleting

Recommended conditioning temperature between 78-85°C (172-185°F) when using feed ingredients that are not heat sensitive. Use typical retention times between 30-45 seconds. Typical moisture addition is between 1-4% which similar conditions used for other cereal grains.

Pelleting Sorghum-Based Diets

• Proper conditioning improves pellet durability and starch digestibility.
• Typical die compression ratios:
  • Poultry: 8:1-12:1
  • Swine: 6:1-10:1
  • Dairy: 5:1-8:1
• Higher compression ratios result in higher pellet quality, and lower ones result in higher pelleting throughput.

Steam Flaking And Extrusion

For steam flaking, common operating conditions include:

• Steam chest temperature: 95-100°C
• Retention time: 20-40 minutes
• Target flake density: 22-28 lb/bu (283-360 kg/m³).

For extrusion applications such as aquaculture and pet food:

• Preconditioner moisture: 20-28%
• Product temperature: 110-150°C
• Retention time: 15-60 seconds

Processing conditions should be adjusted based on the desired final product.

Use of Enzymes

Common enzymes include xylanase, beta-glucanase, protease and phytase to improve nutrient utilization.

Quality Control during Feed Processing

• For all types of feeds, monitor moisture content, mycotoxin (when needed), particle size and mixing uniformity.
• For pelleting, monitor moisture content, temperature, pellet durability index (PDI), fines and in some cases pellet hardness.
• For extruded aquaculture feed, monitor moisture content, temperature, floatability and/or sink rate, size, bulk density, fines, water stability, starch gelatinization, etc.
• For extruded pet food, monitor moisture content, temperature, fines, starch gelatinization, bulk density, size, expansion ratio, palatability, etc.
• For steam flakes, monitor moisture content, temperature, flake density and thickness, fines, start gelatinization, etc.

Processing Challenges

Sorghum has a hard, dense endosperm and smaller kernel size.

Summary

Successful sorghum processing starts with selecting tannin-free sorghum varieties, maintaining proper storage conditions, grinding finer than corn for monogastric diets, and conditioning adequately before pelleting, and monitoring quality regularly. When processed correctly, sorghum can be an effective and economical ingredient across a wide range of animal feed applications.