[Joint research on the precise determination of the energy and protein requirements of fattening pigs. 8. The effect of various protein levels on the performance and feed expenditure of fattening pigs].

Live weight development and feed expenditure were investigated on 3 levels of protein supply and isocaloric rations in scientific feeding experiments with 10 castrated male pigs each of the genetic origin land race pig X large white fed individually in the live weight range between 30 and 100 kg with a subdivision at 60 kg. In the air-dried matter the crude protein content of the feed mixtures used in the first fattening period was 17.6; 15.7 and 13.7% resp. and in the second fattening period from 60 kg live weight onwards 14.9; 12.8 and 11.4% resp. for the 3 test groups. In both fattening periods the digestibility of the rations and the N-balance were determined at 3 representative animals from each of the 3 groups. The following average live weight gains were achieved in the 3 test groups: 1st fattening period: 662; 592 and 539 g resp.; 2nd X fattening period: 709; 676 and 644 g resp. Feed expenditure over the complete fattening period was 4.2; 4.5 and 5.2 kg air-dried matter per kg live weight gain. The highest protein supply resulted in the best live weight gain performance and the lowest expenditure.