[Utilization of feed rations of varying protein content by growing pigs].

In a total of 134 experiments concerning the general metabolism of growing pigs in a live weight range of 10 to 30 kg the nutrient and energy retention were investigated under the conditions of ad libitum feeding and feeding on the maintenance level including two fasting days, providing four rations with different protein concentration (16 to 22%). N-utilisation was ascertained as 81.2 +/- 4.2% and N-maintenance requirement as 0.199 g N per kg live weight0.75. The utilisation level of metabolisable energy (ME) was independent of the protein level but dependent on the method of calculation. The utilisation value of 73.8 +/- 3.0% was calculated as the best adaptation to the balance experiments altogether. It corresponds to the energy maintenance requirement of 434 kJ ME/kg live weight0.75. The standards of the energy requirement of growing pigs in the live weight range of 10 to 50 kg are derived from this results and earlier experiments and put up for discussion.