Because of the presence of antinutritional factors, the use of soybean meal in weanling pig diets is limited. Animal protein sources can be used, but their cost is high relative to plant protein sources. Therefore, it is economically advantageous to find high quality plant protein sources that weanling pigs can tolerate.

Soybean meal can be processed in various ways to remove or reduce antinutritional factors. One way is to use an alcohol extraction process to remove water-soluble carbohydrates, followed by heat treatment. This process produces soy protein concentrate. An experiment was conducted to determine effects of feeding a soy protein concentrate product called X-SOY 200 on growth performance and blood parameters in weanling pigs.

A total of 160 pigs with an average initial body weight of 7.06 kg were used in this study. The experiment was conducted during two phases of two weeks each. Pigs were fed one of four corn-soybean meal based diets during phase 1. The control diet contained 5% spray dried protein plasma, 5% fish meal, and no X-SOY 200; the second diet contained 5% plasma, no fish meal, and 5.25% X-SOY 200; the third diet contained no plasma, 5% fish meal, and 8% X-SOY 200; and the fourth diet contained no plasma, no fish meal, and 13.25% X-SOY 200. The phase 1 diets were formulated to contain equal amounts of digestible amino acids. All pigs were fed a common diet based on corn and soybean meal during phase 2.

Pigs were weighed at the beginning of the experiment and at the conclusion of each phase. Average daily gain, average daily feed intake, and average gain:feed ratio were calculated for each treatment group.

On the last day of the experiment, blood was collected from the pig in each pen with a body weight that was closest to the pen average. The blood samples were analyzed for tumor necrosis factor-α, immunoglobulin G (IgG), peptide YY (PYY), blood urea nitrogen (BUN), albumin, and total protein.

There was no difference in final body weight, average daily feed intake, average daily gain, or gain:feed ratio among pigs fed the control diet or any of the X-SOY diets in phase 1 (Table 1). In addition, there was no difference in growth parameters in phase 2 or over the entire experimental period.

The concentrations of TNF-α, PYY, IgG and BUN in the blood were not different in pigs fed any of the four diets (Table 2). There was a tendency for total protein (P = 0.078) and albumin (P = 0.08.2) to increase as the inclusion rate of X-SOY200 increased.

• X-SOY 200 may be substituted for blood plasma, fish meal, or both in diets fed to weanling pigs at an inclusion rate of up to 13.25% without affecting growth performance.
• Substituting X-SOY 200 for blood plasma or fish meal in weanling pig diets does not affect indicators for proinflamatory immune parameters or general metabolism.

Table 1. Growth performance of pigs fed the control diet or diets containing X-SOY200

Table 2. Blood parameters in pigs fed control diet and diets containing X-SOY200

This report is based on unpublished research by Gloria A. Casas and Hans H. Stein.