Nutritional evaluation of sunflower seed and products derived from them. Effect of oil extraction

1. Apparent MEn and oil digestibility of hulled sunflower seed (SFS) and th e products derived from the oil extraction process: press extracted SFS (PE SFS), sunflower seed meal (SFSM), and press and solvent oils (PO and SO)-we re determined with 198 cockerels. Recombined products (mix of meal and oil) were also evaluated to study the effect of the 2 consecutive oil extractio n steps. Each foodstuff was included in a basal diet? according to the prop ortions resulting from processing, at 100, 200, and 300 g SFS/kg. 2. Dietary energy value and digestible fat content were linearly related to rate of inclusion of test ingredients. Extrapolation values for AME(n) (MJ /kg DM) were: SFS, 16.20; PESFS, 9.46; SFSM, 7.62. A decreasing quadratic t rend was also found in the AME(n) of PESFS, with interpolation values rangi ng from 11.77 to 9.33 MJ/kg DM between 70 and 210 g/kg DM of inclusion. No differences were observed between PO and SO. The AME(n) of of sunflower oil , calculated from its digestibility, was 33.70 MJ/kg DM. 3. The oil extraction process affected the nutritional value of sunflower p roducts. Recombined materials shelved gl-Pater values than original foodstu ffs: R-SFS, 17.41; R-PESFS, 11.49 MJ/kg DM. The increase in oil digestibili ty (from 0.814 to 0.862 g/kg DM in SFS; from 0.778 to 0.892 in PESFS) accou nted for most of the increase observed in AME(n) values. 4. As the form in which oil is incorporated in diets (released or within SF S or PESFS) affects the utilisation of sunflower products, their nutritiona l value is less than maximal and should not be calculated from their ingred ients. Solvent oil seems to be the less available fraction of sunflower oil within SFS as the effect of the 2nd extraction proved to be greater than t hat of the previous press extraction.