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.