[Isobutylene diurea as a new source of NPN for ruminants. 1. Nitrogen balance and plasma amino acid composition after feeding of isobutylene diurea to sheep].

The paper first presents a survey of the existing literature where studies on the effects of isobutylidene diurea (IBDH) as NPN source for ruminants are discussed. Following this the authors discuss their own experiments on IBDH turnover. IBDH showed no toxi cation when tested in toxicity studies with rats which were carried out under standardized conditions. Within the framework of metabolism trial 4 growing male sheep (average liveweight: 30 kg) were fed a semisynthetic diet containing IBDH as sole N source. Each animal received 60 g IBDH per day. The average value for the apparent N digestibility was found to be 77.6%, the percentage for the average N ballance was 27.6%. The blood of the sheep was investigated, on a comparative basis, for the behaviour of free amino acids after the administration of an experimental semisynthetic diet containing IBDH or extracted soya bean meal as sole N source. The use of IBDH produced a higher concentration of free amino acids and a five-fold increase if urea concentrations in the blood plasma but reduced the Asp, Cys and Tyr levels when compared with the feeding of extracted soya bean meal. Similarly, IBDH supplementation increased the relative proportions of Gly, Lys, and His in blood plasma but reduced those of Asp, Val and Tyr. A positive relationship between the rate of IBDH hydrolysis and the decrease in pH was found in experiments studying the hydrolysis behaviour of IBDH at pH values from 1-7.