Chemical composition, digestibility and protein quality of 12 sunflower (Helianthus annuus L) cultivars

Twelve sunflower (Helianthus annuus L) cultivars grown in Spain were analys ed and tested in experiments with rats. The dehulled seeds contained an ave rage of 32.2 MJkg(-1) dry matter (DM) gross energy, 653 g kg(-1) DM fat, 60 g kg(-1) DM total non-starch polysaccharides (NSP) and 6 g kg(-1) DM Klaso n lignin. The sunflower seed hulls contained 20.2 MJkg(-1) DM gross energy, 53 g kg(-1) DM fat, 562 g kg(-1) DM total NSPs and 239 g kg(-1) DM Klason lignin. The sunflower samples were dehulled and partially defatted (to simi lar to 17% fat) and included in diets for rats. The dehulled, partially def atted samples contained on average 74.6g nitrogen kg(-1) DM and 1.409 mg g( -1) phenolic compounds (chlorogenic acid+caffeic acid+derivative 1+derivati ve 2) varying from 0.677 to 2.847 mg g(-1). Groups of five growing rats wer e fed diets (9.38% crude protein) containing one of the sunflower cultivars as the only source of protein. Apparent heal and faecal digestibilities we re determined by using an indigestible marker (Cr2O3) and faecal digestibil ity based on total faecal collections. Apparent ileal, caecal and faecal di gestibilities of organic matter were 81.2-91.5% (P = 0.05), 95.8-97.1% (P = 0.005) and 94.7-95.3% (P = 0.94) respectively. The apparent faecal digesti bilities of DM, energy and protein (N x 6.25) were 93.2-93.8%, 93.5-94.3% a nd 81.6-83.3% respectively with no differences among cultivars. Biological value (BV) ranged between 63.8 and 73.2% (P = 0.0001) and net protein utili sation (NPU) between 59.9 and 69.5% (P = 0.0001). BV and NPU were positivel y correlated with lysine and threonine contents, but no correlation with th e analysed phenolic compounds was detected. (C) 1999 Society of Chemical In dustry.