Estimation of Tryptophan Requirements for High Growth Rate in Pigs at 15 kg Live Weight.
I. Preliminary Investigations at Six Different Levels of Tryptophan Allowance Within 9 Days of Test

Agricultural Faculty at Christian-Albrecht University, Olshausenstraße 40, 24118 Kiel, Germany


SIMEONOVA, M. L., 2001. Estimation of tryptophan requirements for high growth rate in pigs at 15 kg live weight. I. Preliminary investigations at six different levels of tryptophan allowance within 9 days of test. Bulg. J. Agric. Sci., 7: 627-634

In order to estimate the requirements of tryptophan for maximal growth performance in growing pigs at a starting live weight of around 15 kg the empirical method as described by Langer (1995) was used. Two consequently identical experiments were carried out on 48 young hybrid animals from genotype selected for high growth rate. In each experiment within 9 test days the animals were separated in six experimental groups of 4 animals, each one allocated to each of 6 tryptophan treatments. To ensure a gradually increasing of tryptophan content, the diets were formulated from a basal diet (13.1 MJ ME/kg fresh substance, 17.1 % CP, 12.3 g Lysine/kg fresh substance, 88 % DM) with supplementation of amino acids according to the “ideal protein concept” to ensure 6 different levels of tryptophan content (0.16, 0.17, 0.19, 0.20, 0.22 and 0.24 Tryptophan/Lysine). Using the data sets presented in this preliminary investigations within 9 days of test, it is to conclude that a total tryptophan / total lysine ratio bellow 0.18 is unsufficient for achievement of maximal growth performance. Until total tryptophan / total lysine ratio at 0.19 to 0.24, the expected tendency of clearly gradually distinguishable increasing the means of the growth performance trait with increasing of tryptophan allowance was not manifested. The present work stresses the need for future detailed investigation in this area.

Key words: growth in the pig, tryptophan requirement, mathematical modelling
Abbreviations: ADG = daily live weight gain (kg/day); CP = crude protein; DM = dry matter; FCR = feed conversion ratio; FDT = age at the first day of test (in days); FI = daily feed intake (kg/day); FLW(kg) = final live weight (kg); ILW(kg) = initial live weight (kg); STRP1 and STRP2 = first and second experiment