Soy protein concentrate is produced by extracting some of the non-protein components of soybean meal, including soluble carbohydrates, from soybean meal. These soluble carbohydrates include oligosaccharides, which reduce the tolerance of young pigs to conventional soybean meal. With the oligosaccharides removed, soy protein concentrate can be used as a source of protein in diets for weanling pigs.

Most soy protein concentrate is produced using an alcohol extraction process. However, a new source of soy protein concentrate called Nutrivance (Midwest Ag Enterprises Inc., Marshall, MN) has recently been introduced, which uses a process combining non-alcohol extraction and enzymatic treatment of soybean meal. An experiment was conducted to determine the apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of phosphorus in this new ingredient.

Forty weanling barrows with an average initial body weight of 14.12 kg were fed one of four diets. Two diets contained soy protein concentrate and soybean meal, respectively, as the sole sources of phosphorus. The diets were formulated to contain the same concentration of phosphorus. Two additional diets were identical to the first two diets with the exception that 2000 FTU of microbial phytase/kg were added.

After a five day adaptation period to the diets, fecal samples were collected to determine the amount of phosphorus excreted and to calculate the ATTD of phosphorus. Using the value for the endogenous loss of phosphorus published in the 2012 NRC (190 mg/kg DMI), the ATTD was corrected for endogenous loss to calculate STTD.

The phosphorus concentration, as well as the proportion of phytate bound phosphorus, was similar in soybean meal and soy protein concentrate (Table 1). Because the process used to create soy protein concentrate removes carbohydrates from soybean meal, it was expected that the concentrations of remaining components, including phosphorus, would be greater than in soybean meal. That this was not the case may indicate that the process used to create this particular source of soy protein concentrate may also have resulted in removal of some phosphorus.

Both intake and excretion of phosphorus were greater (P < 0.01) for soybean meal than for soy protein concentrate. However, ATTD and STTD of phosphorus did not differ between pigs fed soybean meal and pigs fed soy protein concentrate with no added phytase.

When phytase was added to the diets, the ATTD and STTD of phosphorus increased (P < 0.01) in both soybean meal and soy protein concentrate. There was no difference between the two ingredients in response to phytase.

• There was no difference in phosphorus digestibility between soybean meal and Nutrivance soy protein concentrate.
• Addition of microbial phytase to diets containing soy protein concentrate increase the digestibility of phosphorus.
• Soy protein concentrate, like soybean meal, is a rich source of digestible phosphorus.

Table 1. Mineral composition of soybean meal (SBM) and soy protein concentrate (SPC), as fed-basis

Table 2. Apparent total tract digestibility (ATTD) and the standardized total tract digestibility (STTD) of phosphorus in soy protein concentrate (SPC) and soybean meal (SBM) with 0 FTU¹/kg or 2000 FTU/kg microbial phytase added

^a-dLeast squares within a row lacking a common superscript letter are different (P < 0.05).

¹FTU= phytase units. The phytase used was Optiphos 1000 (1,000 FTU/g; Enzyvia, Sheridan, In).

This report is based on unpublished research by Maryane Sespere Oliveira and Hans H. Stein.