The effect of different grinding and thermal treatment procedures of rapeseed on feed value for growing pigs

Digestibility experiments with pigs at 60-70 kg live weight were conducted according to the difference method to study the effects of different grindi ng methods on digestibility of nutrients and metabolizable energy content o f full fat rapeseed. Rapeseed was ground on a roller mill with a coarse or fine adjustment or ground on a flake mill to give meals with average partic le diameters of 1.04 0.39 or 0.56 mm, respectively. Furthermore, the influe nce of different thermal treatments (micronizer, 105 degrees C and 125 degr ees C, jet sploder, 105 degrees C and 125 degrees C, hydrothermal condition ing, 98 degrees C and 105 degrees C) on reduction of glucosinolates and on digestibility of nutrients of rapeseed was tested. Digestibility of organic matter of 78 % and metabolizable energy contents of 19.2 and 20.4 MJ ME/kg dry matter were attained by feeding of thoroughly ground rapeseed (flake m ill and fine adjusted roller mill, respectively). Digestibility was decreas ed by 13 % units and ME content by approximately 3 MJ/kg dry matter by coar se adjusted roller mill. The thermal treatments, especially the hydrotherma l procedure, reduced the glucosinolate content bur the effects on nutrient digestibility and ME content were not always consistent. Rapeseed treated w ith the micronizer at 105 degrees C tended to increase the feed value.