[Abstract nur auf Englisch verfügbar.] The aim of this study was to estimate the maintenance requirement for each essential amino acid for N-equilibrium. Therefore six trials including 183 N-balances were conducted. The only source of N in the chemically defined diet were cristalline amino acids. The respective amino acid under study was fed in various contents in the diet. The amino acid pattern of the diets was adjusted to the requirement estimated by FULLER et al.(1989) for growing pigs. The contents of the examined amino acid in the diet were 100, 60, 30 and 0 % of the estimated requirement. The contents of all other amino acids were constant at the level of 120 % of the estimated requirement. On average, the supply of nitrogen was 312 mgN/kg0.75/d. Each group consisted of four sows, to which the diets of one amino acid were given in descending sequence of the contents of the amino acid. The excretion of N in feces, urine, skin and hair was measured. Then the N-balance was set into correlation to the input of the amino acid intake. The requirement of one amino acid was determined at N-equilibrium using the linear regression equation. The requirements of the amino acids are as follows: Thr 40 mg/kg0.75/d, Lys 38 mg/kg0.75/d, Met+Cys 37 mg/kg0.75/d, Trp 11 mg/kg0.75/d, Phe 17 mg/kg0.75/d, Ile 20 mg/kg0.75/d, Val 23 mg/kg0.75/d.When the losses by skin and hair are included the requirements are as follows: Thr 43 mg/kg0.75/d, Lys 47 mg/kg0.75/d, Met+Cys 39 mg/kg0.75/d, Trp 12 mg/kg0.75/d, Phe 20 mg/kg0.75/d, Ile 24 mg/kg0.75/d, Val 25 mg/kg0.75/d. The effect of a N-free diet was tested also. The most negative balance of all studies was achieved with the complete omission of N. The depletion of one amino acid reduced its concentration in blood plasma. The results of this study elucidate that the amino acid pattern required for maintenance is different from that for protein accretion or lactation, such as greater importance of Thr, Met+Cys and Trp compared to Lys. The portion of Phe and Val in the "Ideal Protein" is decreased. The estimated results may serve to the factorial estimation of requirement for pigs. It is then possible to create the pattern of the "Ideal Protein" for an animal in a certain physiological status to realize it under practical feeding conditions.
«