Soybean meal is a high quality source of protein for swine diets. Due to the growth in global production of pigs and poultry, demand for soybeans is increasing rapidly, outpacing production. Therefore, other sources of plant protein are being sought to lower feed costs.

The most abundant oilseeds produced in the world, aside from soybeans, are cottonseed, canola seed (rapeseed), and sunflower seed. These may be fed as de-oiled meals, or the full fat seeds can be fed to increase the energy concentration of the diet.

These other oilseeds have less favorable amino acid profiles and lower apparent digestibility of amino acids than soybean meal. However, for more accurate comparisons of feed ingredients, standardized digestibility should be determined. This experiment was performed to find standardized ileal digestibility (SID) values for seven oilseed products fed to finishing pigs.

In this experiment, pigs were fed diets containing canola seeds (CS), and canola meal (CM), cottonseed meal (CSM), sunflower seeds (SFS), sunflower meal (SFM), dehulled sunflower meal (SFM-DH), and dehulled soybean meal (SBM). In addition, an N-free diet was used to estimate basal endogenous losses of crude protein and amino acids.

Crude protein and amino acid content of oilseed-based feed ingredients

Of the oilseed-based feed ingredients studied, SBM had the greatest concentrations (P < 0.01) of crude protein, total indispensable amino acids, and most individual amino acids (Table 1). The concentration of methionine was greatest (P < 0.01) in SFM-DH. After soybean meal, canola meal and cottonseed meal contained the greatest concentrations of crude protein and total indispensable amino acids.

Among canola products, the concentrations of crude protein and all amino acids were greater (P < 0.01) in CM than in CS.  Similarly, among sunflower products, the concentrations of crude protein and all amino acids were greater (P < 0.01) in SFM-DH than in SFS and SFM. The concentrations of crude protein and all amino acids, except arginine and tyrosine, were greater (P < 0.01) in SFM than in SFS.

Standardized ileal digestibility of crude protein and amino acids

Soybean meal had greater (P < 0.05) SID of crude protein and all indispensable amino acids (except tryptophan, for which no conclusions could be drawn) than all other oilseed products (Table 2). Soybean meal, sunflower seeds, and sunflower meal had the greatest values for standardized ileal digestibility of crude protein and most amino acids. For total indispensable amino acids as well as most individual indispensable amino acids, no difference in SID between SBM, SFS, and SFM was observed.

Among sunflower products, no differences among SFS, SFM, and SFM-DH were observed for the SID of crude protein, arginine, tryptophan, and lysine. For all other indispensable amino acids (except tryptophan), SID was less in SFM-DH than in one or both of SFS and SFM. Among canola products, CM had greater SID of most indispensable amino acids than CS.

Key points

• Increasing global demand for soybeans is pushing up the price of soybean meal, which in turn could make the use of other oilseeds in swine diets economically attractive.
• Of the oilseed products studied, canola meal and cottonseed meal contain the greatest concentrations of crude protein and indispensable amino acids after soybean meal.
• Soybean meal, sunflower seeds, and sunflower meal had the greatest values for standardized ileal digestibility of crude protein and most amino acids.

Table 1. Analyzed protein composition of canola seeds (CS), canola meal (CM), cottonseed meal (CSM), sunflower seeds (SFS), sunflower meal (SFM), dehulled sunflower meal (SFM-DH), and soybean meal (SBM), as-fed basis

Table 2. Standardized ileal digestibility of CP and AA in canola seeds (CS) , canola meal (CM), cottonseed meal (CSM), sunflower seeds (SFS), sunflower meal (SFM), dehulled sunflower meal (SFM-DH), and soybean meal (SBM)

This research report is based on unpublished research by J. C. González-Vega and H. H. Stein.