Almeida, F. N., J. K. Htoo, J. Thomson, and H. H. Stein. 2014. Digestibility by growing pigs of amino acids in heat-damaged sunflower meal and cottonseed meal. J. Anim. Sci. 92:585-593. Link to full text (.pdf)

Rodríguez, D. A., R. C. Sulabo, J. C. González-Vega, and H. H. Stein. 2013. Energy concentration and phosphorus digestibility in canola, cottonseed, and sunflower products fed to growing pigs. J. Anim. Sci. 91(Suppl. 2):116-117 (Abstr.) Link to abstract (.pdf)

Sunflower meal and cottonseed meal can be used in place of soybean meal as protein sources for swine diets. The production of both involves heat treatment, to extract oil from sunflower seeds and cottonseeds and to reduce antinutritional factors. When heat is applied to feed ingredients in the presence of moisture, a series of chemical reactions known as the Maillard reaction may be initiated.  In the Maillard reaction, amino acids and reducing sugars combine to form indigestible compounds known as Amadori compounds. These amino acids are therefore not available to the pigs. Lysine is particularly susceptible to the Maillard reaction. It is important to know the extent of heat damage in feed ingredients so that diets may be formulated that supply the appropriate amounts of digestible amino acids to pigs.

Little information is available about the effects of heat processing on amino acid digestibility in sunflower meal and cottonseed meal. Furthermore, equations to predict the concentration of digestible amino acids in sunflower meal and cottonseed meal from the analyzed nutrient composition have not been reported. Two experiments were conducted to determine the standardized ileal digestibility (SID) of amino acids in sunflower meal and in cottonseed meal fed to growing pigs, and to test if regression equations could be developed to predict the concentration of SID lysine in sunflower meal and cottonseed meal.

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

Oilseeds and oilseed meals also provide phosphorus to the diet. However, most of the phosphorus in these sources is bound to phytate, and is not available to pigs. An experiment was performed to determine the standardized total tract digestibility (STTD) of phosphorus in canola, cottonseed, and sunflower products, and to discover how the addition of phytase influences the STTD of phosphorus. The apparent total tract digestibility (ATTD) of calcium and the effect of adding phytase on ATTD of calcium were also measured.

González, J. C. and H. H. Stein. 2011. Digestibility of AA in canola-, cotton-, and sunflower-products fed to finishing pigs. J. Anim. Sci. 89(E-Suppl. 2):100 (Abstr.) Link to abstract (.pdf)