COMPOSITION AND DIGESTIBILITY BY PIGS OF HULL FRACTIONS FROM RAPESEED CULTIVARS WITH YELLOW OR BROWN SEED COATS

Abstract

Hull fractions from yellow seed (Brassica campestris 'R-500') and brown seed (Brassica napus 'Tower') cultivars of rape were fed to pigs at levels of 0, 15 and 30% of the diet in a digestibility trial. Whole seed, 'meats' (embryo) and hull fractions were analyzed for moisture, protein, ether extract, crude fiber, neutral and acid detergent fiber, lignin, ash, calcium, phosphorus, sinapine, glucosinolates and gross energy. Brown hulls contained more fiber and lignin. The embryo content of the yellow hulls fraction was greater than that of the brown hulls fraction. Increasing dietary levels of hulls depressed digestibility of dry matter, energy, crude fiber and ether extract. Brown hulls had the greatest effect. The effect on ether extract digestibility may have been due to lower digestibility of unextracted oil in embryo fractions adhering to hulls. The digestibility coefficients of Tower and R-500 added oils were 87 and 75%, respectively, and the same oils residing in the meats were 36 and 44% digestible. The energy components of hulls per se were more digestible in R-500 than in Tower. Protein of Tower hulls was indigestible, but R-500 hull protein was about 20% digestible. Key words: Rapeseed hulls, yellow brown, composition, digestibility, pigs