A COMPARISON OF SOYBEAN MEAL AND TOWER RAPESEED MEAL AS SUPPLEMENTS TO CORN IN DIETS OF GROWING-FINISHING AND HEAVY WEIGHT PIGS

Abstract

Ninety-six Yorkshire barrows and gilts were used in each of two experiments conducted in the spring-summer (exp. 1), and fall-winter (exp. 2) months, respectively, to evaluate 15% Tower rapeseed meal (RSM) as a partial replacement for soybean meal (SBM) on an isonitrogenous basis in corn-based diets for pigs from 23 to 91 kg body weight. At 91 kg, half the number of pigs in each dietary group were slaughtered. Then, three levels of protein (12, 14 and 16%) in both corn-SBM and corn-SBM-RSM diets were fed to the remaining pigs in each group up to a final body weight of 125 kg. The energy level in the RSM diets was not adjusted to equal that in the SBM diets. In the 23- to 91-kg gain period, average daily gain (ADG) (P < 0.01) and backfat (P < 0.05) were lower in the RSM-fed pigs compared to SBM-fed pigs only in exp. 2. From 91 to 125 kg body weight, ADG (P < 0.05), feed intake (P < 0.01) and backfat (P < 0.01) were lower for RSM-fed pigs only in exp. 2. The heavy weight pigs fed RSM diets had a lower (P < 0.01) dressing percentage than SBM fed pigs in exp. 1. Reduction of dietary protein from the 16% fed up to 91 kg body weight to either 14 or 12% in the 91- to 125-kg gain period did not affect performance.