[Effect of protein restriction and refeeding on the nitrogen balance in piglets]

In balance trials the effect of a 50% protein restriction with subsequent realimentation on N balance, endogenous N excretion, digestible and metabolisable energy was tested using 36 piglets. The dietary protein content during the restriction period from 5-12 kg live weight was 22.9 (control) and 12.4% of the dry matter and during the realimentation period from 12-18 kg live weight in both groups 17.2%. Protein quality and energy supply were not changed between the groups. Restricted protein supply proportionally reduced N retention with slightly improved efficiency of digestible N from 67 to 70%. During realimentation the previously reduced N supply did not influence N retention but increased the apparent N digestibility by 2% units. The endogenous N losses as well as digestible and metabolisable energy were not different between the groups. It was concluded that compensatory responses of the N metabolism might require a stronger dietary restriction and respectively or a longer restriction period.