Nutritional value of yellow-seeded winter rapeseed cakes for growing pigs
Objective of the study was to compare the composition and nutritional value of a winter brown- (BRC) and three yellow-seeded (YRC) cold-pressed rapeseed cakes as the components of pigs’ diets, and to assess their effects on colonic bacterial fermentation and the relative weight of organs. In experiment 1, the standardised ileal digestibility (SID) of protein and amino acids (AA) of cakes was determined in 12 male cannulated pigs. Each diet was fed to six pigs during three seven-day periods. Ileal digesta was collected during the last three days of the period. In experiment 2, five groups each containing six female pigs with initial body weights (BW) of 20 kg were fed on diets containing BRC, YRC, or soyabean oil meal (SBM) as the main protein source. The apparent total tract digestibility (ATTD) of nutrients and growth performance were measured untill 60 kg BW was reached, and short chain fatty acids (SCFA) concentrations in the colon, as well as the weight of the liver, kidney, heart, and thyroid, were recorded. The main differences between BRC and YRC were found in higher content of fat and protein, lower amounts of fibre and glucosinolates (Gls), and higher ATTD of fibre in YRC. Protein and AA SID, ATTD of nutrients, total SCFA colonic concentration, and growth performance did not significantly differ. The chemical composition of the three YRC was not uniform, the greatest differences were found among the amounts of Gls. The relative weights of the thyroid and heart were greater in pigs fed BRC than in YRC and SBM diets. Thyroid weight was positively correlated with dietary progoitrin, alkenyl Gls, and total Gls, whereas heart weight was positively correlated with progoitrin and alkenyl Gls. It was concluded that winter yellow-seeded rapeseed is a better raw material for cold-pressing than brown-seeded due to having lower Gls and fibre content.