NUTRITIVE-VALUE OF TOWER RAPESEED MEAL FOR SWINE

Two experiments were conducted involving 144 Yorkshire .times. Lacombe gilts, with an average initial weight of 20 kg. In experiment 1 the gilts were allotted to a control diet containing soybean meal (SBM) or to diets in which either 50% or all of the supplementary protein was provided by Tower rapeseed [Brassica napus] meal (RSM). In the 2nd experiment the 2 diets had either SBM or Tower RSM as the supplementary protein source. In a 3rd diet Tower RSM was supplemented with sufficient lysine to equal the calculated available lysine level of the SBM control diet. Gilts given the SBM diet grew from 20-60 kg significantly faster (P < 0.01), and had better feed conversion efficiency (P < 0.01), than those given the RSM diets. A 50% replacement of SBM by Tower RSM gave intermediate results. Partial or total replacement of SBM by Tower did not significantly affect the growth rate or feed conversion efficiency of the gilts when growing from 60 to 100 kg live wt. Serum triiodothyronine (T3) and thyroxine (T4) concentrations of the gilts at 100 kg were lower in pigs fed on the RSM diets but the differences were not significant. Total replacement of SBM by Tower RSM, with or without the addition of lysine, significantly (P < 0.001) reduced growth rate and feed conversion efficiency during the growing period (20-60 kg) but did not significantly affect performance during the finishing period (60-90 kg). Serum T3 concentration was not significantly affected by the addition of Tower RSM to the diet but T4 concentrations were significantly reduced (P < 0.01). None of the carcass parameters studied were significantly affected by the addition of Tower RSM to the diets.