Dr. Güvenç İnan
R&D Director 
Erişler  Yem Sanayi A.Ş. 

Applying high heat and pressure via expander technology significantly enhances starch gelatinization, bypass protein levels, and overall nutrient digestibility in ruminant feeds. Beyond delivering 50–70 kcal/kg gains in metabolizable energy and improving herd productivity, advanced expander processing optimizes pellet durability and operational throughput for industrial feed mills.

WHAT IS EXPANDED PRODUCTION?

It is the process in which a raw material or feed ingredient is exposed to moisture, pressure, and temperature to gelatinize its starch content, followed by a sudden pressure drop that increases the volume of the material (Svihus et al., 2005).

An expander consists of a thick-walled metal line resistant to high pressure and temperature (Thomas & van der Poel, 1996). Conveyed along the line via an electric motor and gears, the feed mixture is subjected to high heat and pressure. As the feed moves through the line, it is mixed to obtain a homogeneous structure. Depending on the feed ingredients, pressure ranges between 50–70 bar and temperature between 90–130°C.

Under high heat and pressure, the starch content of the feed mixture gelatinizes. The discharge end of the expander features a hydraulically adjustable conical gap (Heidenreich, 2004). Upon reaching this gap, the feed mixture (having been exposed to high heat and pressure) expands volumetrically when it suddenly encounters ambient temperature and atmospheric pressure. This process is referred to as “expanding.” The equipment derives its name, expander, from this concept. It takes about 10 seconds for the feed mixture to pass through the expander.

WHAT ARE THE BENEFITS OF EXPANDED FEED PRODUCTION? 

The volumetric expansion of feed raw materials provides several advantages in ruminant nutrition. The digestibility of starch, fat, and fiber in expanded feed increases, thereby elevating the feed’s metabolizable energy level (Lund, 2002).

The most pronounced change and beneficial effect in expanded grains stems from starch gelatinization (Svihus et al., 2005). Higher starch gelatinization enhances the digestibility of the starch contained within the grains. Grains such as corn and barley thus become highly digestible when expanded, preventing the issue of undigested grains being excreted in manure, which is particularly observed in dairy and beef cattle (Owens et al., 1997).

Figure 1: Expander Production Line

Because expanded feeds exhibit higher digestibility than pelleted or mash feeds, they yield higher energy values in practice than those mathematically calculated in the laboratory. Thanks to expander processing, the increase in metabolizable energy value for high-starch and high-fat feeds can reach up to 50–70 kcal/kg (Lund, 2002).

Expanded feeds are more hygienic than pelleted feeds. The high temperature and pressure applied during expanded production ensure the elimination of anti-nutritional factors and pathogenic microorganisms in the feed (Peisker, 2006). Expanded feeds are also more palatable compared to pelleted feeds of the same composition. Higher feed intake and increased dry matter consumption positively impact milk and meat yields.

Expanding feeds also induces changes in protein structure. Expanded feeds contain a higher proportion of bypass protein compared to pelleted feeds with identical formulations (Aldrich et al., 1995). An increased bypass protein ratio allows for higher milk production, particularly in high-yielding cows during early and mid-lactation.

Beyond nutritional advantages, expander feed production offers operational benefits within feed mills. Expanded feed production positively affects pellet quality and press throughput capacity (Thomas & van der Poel, 1996). It allows for higher inclusion rates of liquid raw materials in feed formulations.

Figure 3: Crown Expander Product Discharge Section

CROWN EXPANDER:

The Crown expander is a novel technology that not only expands feed mixtures or grains but also shapes them into products with the desired physical structure (Amandus Kahl, 2018).

Compared to standard expander production, the Crown expander generally enables the application of higher temperatures and pressures, leading to even higher digestibility levels of the processed raw material or feed mixture. In the Crown expander process, the outlet temperature reaches up to 140°C (Heidenreich, 2004).

Commonly used raw materials in ruminant nutrition, such as corn, barley, and soybean meal, can be processed on the Crown expander line. When corn and barley are processed via the Crown expander, high starch gelatinization is achieved through high heat and pressure, maximizing the digestibility of these grains. Any application that improves grain digestion allows animals to yield more milk and meat per unit of corn or barley consumed. During Crown corn production, higher starch gelatinization is achieved compared to flaked corn (Owens et al., 1997; Zinn et al., 2002; Heidenreich, 2004; Svihus et al., 2005). This improves digestibility, enabling increased milk and meat yields.

Along with starch digestion, Crown expander production also improves the digestibility of fat and fibrous material in grains. Consequently, the digestible energy level of processed corn or barley is maximized.

Figure 2: Expanded feed

Processing soybean meal under high temperature and pressure in the Crown expander line yields a product with a high bypass protein content. Analysis results indicate an increase of nearly 30% in bypass protein levels (Aldrich et al., 1995). In the resulting product, named Crown Soya, heat damage (Maillard reaction) is prevented due to controlled temperatures and retention times, ensuring no adverse effect on total protein digestibility in the small intestine.

While analytical reports indicate that the protein in standard soybean meal is predominantly degraded in the rumen, Crown Soya exhibits reduced rumen degradation, shifting digestion primarily to the intestines as bypass protein (Aldrich et al., 1995). This is particularly critical for feeding high-yielding animals in early lactation. Supplementing rations with rich bypass protein sources during these periods can yield additional gains in milk output.

Figure 4: Crown corn

Widely used feedstuffs in ruminant nutrition, such as corn, barley, and soybean meal, can be processed individually through the Crown expander line. Alternatively, depending on operational needs, formulations such as corn-barley mixtures, corn-soybean meal mixtures, or a combination of all three raw materials can be produced.

Expanded feed production and its advanced form, Crown expanded production, delivers significant advantages in ruminant nutrition, making positive contributions to herd health and overall operational efficiency.