In 1978, the length of a 6-month-old gilt was about 110 cm (~ 43 in) and weighed about 100 – 110 kg (220-242 lb). Weaning efficiency was around 18-21 pigs per sow per year. Piglets were weaned at 40-45 days to maximize milk production of the lactating sows.
Today, modern sows can produce 35-40 pigs per sow per year – almost double the performance of sows 39 years ago. Body length, growth rate, feed intake, and milk production of lactating sows were pushed forward through genetic development and nutrient density.
However, the selection of superior genetics has affected other traits. For example, modern sows are highly sensitive to heat, resulting in the reduction of their daily feed intake, which affects reproductive performance and milk production in lactating sows. As a solution, feeding specific levels of energy and lysine can counteract heat stress effects on the volume of sow milk production.
An effective and inexpensive source of energy and amino acids for modern sow feed is protein-rich soybeans. However, soybeans cannot be fed raw because anti-nutritional factors like trypsin inhibitors, urease, and lectins are not inactivated unless the soybean is processed. Anti-nutritional factors adversely affect the digestive efficiency. Thus, there is a need to process or cook the raw soybeans.
There are several methods of processing or cooking soybeans, including: toasting, micronization, expansion, solvent extraction, high shear dry extrusion, and wet extrusion. One research study by McNab and colleagues (1985) showed amino acid digestibility using different processing methods. The authors concluded that high shear dry extrusion was an efficient way to process soybeans by inactivating anti-nutritional factors and improving protein digestibility in chicks.
When processing soybeans for feeding modern sows, proper processing temperature is critical to inactive anti-nutritional factors, while increasing protein digestibility. It has been scientifically concluded that high shear dry extrusion of soybeans should reach the minimum processing temperature that we recommend to our customers. Recently, Dr. Carl Parsons from the University of Illinois (Urbana-Champaign) showed the following data for amino acid digestibility and metabolizable energy of high shear dry extruded full-fat soy (EFFS) at proper processing temperature. When EFFS was fed to chickens, the digestibility of cysteine and threonine increased, while methionine and lysine remained similar when compared with solvent extracted soybean meal. Additionally, birds fed EFFS had 68% more metabolizable energy than birds fed solvent extracted soybean meal.
In conclusion, high shear dry extrusion under proper processing temperatures improves the nutrient value of EFFS providing an excellent source of palatable fat and energy in the diets of modern sows. Additionally, EFFS contains highly digestible protein and amino acids allowing for improved digestibility. Overall, there are many advantages to high shear dry extrusion processing of soybeans over other processing methods.