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Two experiments were carried out on 48 growing Polish Landrace pigs, from 30 to 60 kg liveweight. Diets were composed of barley supplemented with rapeseed meal (RSM) or milk powder (C). Rapeseed meal contained 6.6 (RSM-7) or 24.3 ^moles (RSM-24) total glucosinolates per gram fat-free dry matter. In each experiment the animals received the same amount of metabolizable energy and lysine. Glucosinolate intake was different, however: 0 or 3.2 moles in experiment 1 and 3.2 or 10.9 moles per day in experiment 2. Energy retention in the body of animals were measured by the comparative slaughter technique. Feeding the mixture containing RSM significantly increased the weight of the liver, kidneys and thyroid. However, there were no unfavourable effects of RSM on the average daily gain and chemical body composition of the pigs. The pigs in group C produced 2.1% more heat in the body (P = 0.07) than those in group RSM-7 (Experiment 1). Increasing the glucosinolate consumption from 3.2 to 10.9 moles/day (Experiment 2) did not significantly affect heat production.

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Twenty-four Polish Landrace pigs (12 gilts and 12 barrows) fattened from 30 to 95 kg body weight were fed diets containing 18% rapeseed meal (RSM) and full-fat rape seeds (RS) in the following amounts: 0 (group RS-0), 10 (group RS-10) or 20% (group RS-20). The pigs were fed on an individual basis with rations having equal energy, protein and lysine contents. Nitrogen balance was determined at 40, 60 and 80 kg liveweight. Metabolizable energy and protein utilization were determined by the slaughter technique. The thyroid gland, liver and kidneys were weighed and plasma T 3 and T 4 levels assayed. Nitrogen retention was on average 12 and 17% lower (P< 0.01) in groups RS-10 and RS-20 than in RS-0; the negative effect of rape seeds on nitrogen utilization intensified as fattening progressed. Metabolizable energy utilization in pigs receiving 20% RS was 2.5 and 3.4% worse (P <0.05) than in groups RS-10 and RS-0, respectively. As glucosinolates intake increased, the weight of the internal organs rose and T 3 and T 4 levels declined. These changes were not, however, proportional to the amount of glucosinolates intake. The combined use of RSM and RS in the diets of growing pigs had an unfavourable effect on protein and energy utilization.

Groups of 12 growing Landrace pigs with an average body weight of 55 ± 1.5 kg were fed a diet containing from 5 to 30% (Expt. 1) or 0 to 25% (Expt. 2) raw rape seeds. The digestibility of the diet was determined by either the indicator method (Expt. 1) or total collection method (Expt. 2). Metabolizability of energy was also determined in experiment 2. The apparent digestibility of crude protein was not dependent on the proportion of rape seeds in the diet, whereas the digestibility and metabolizability of energy decreased after the rape seed content exceeded 15% (Expt. 2) or 20% (Expt. 1). The mean coefficient of digestibility and metabolizability of energy and apparent digestibility of protein determined by multiple equations when the rape seed content equalled to 15 and 20%, were: 76.1 ± 1.8%, 66.4 ± 2.4% and 75.8 ± 3.5%, respectively. The digestible and metabolizable energy contents and digestible protein content in 1 kg DM of seeds were, respectively: 22.4, 20.2 MJ and 156 g.