Retention and utilization of amino acids in piglets fed ad libitum or restrictively diets supplemented with organic acids

Abstract

In a metabolic trial 4 groups of 8 piglets of 5 kg weight each were kept individually for 45 days (final weight 23 kg) and fed a practical diet. At the beginning of the experiment the body amino acid contents of an additional group of 8 piglets were determined by carcass analysis, and at the end of the experiment the body amino acid contents of the 4 test group piglets (A = control fed ad libitum, B and C = supplement of 1.5 % fumaric acid fed ad libitum or restrictively, D = supplement of 1.5 % citric acid fed ad libitum) were also analysed. The amino acid retention during the experimental period was determined by difference. The supplements of fumaric or citric acid did not influence the amount of the amino acid retention. The quotient of amino acid retention to amino acid consumed or the “productive amino acid value”; was calculated and the maintenance requirements of essential amino acids for piglets were used to estimate the productive amino acid value for both retention and maintenance. The mean amino acid retention amounted to about 56 g/d, i.e. 3.49 g/kg W0.75·d of essential amino acids. The essential amino acid requirements for maintenance was 2.0 g, i.e. 0.29 g/kg W0.75·d, showing a variation of 4 % (Leu) to 20 % (Met+Cys) when related to the amount of the corresponding amino acid retention. With regard to the amino acid pattern for retention of the nutritionally most important amino acids, the following ratios were found: Lys, 100 (6.27 g/16 g N) : Met+Cys, 48 (3.03 g) : Thr, 56 (3.49 g) : Trp, 13 (0.80 g). The productive amino acid values ranged from 40 % (Trp), 55 % (Thr), 66 % (Met) to 80 % (Lys). Under the conditions investigated, neither the supplements of organic acids nor the feed restriction influenced the amino acid utilization.