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Efficiency of amino acid utilization in the growing pig at suboptimal levels of intake: branched‐chain amino acids, histidine and phenylalanine + tyrosine
Author(s) -
Heger J.,
Van Phung T.,
Křížová L.,
Šustala M.,
Šimeček K.
Publication year - 2003
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1046/j.1439-0396.2003.00406.x
Subject(s) - phenylalanine , valine , amino acid , leucine , tyrosine , isoleucine , histidine , chemistry , amino acid synthesis , biochemistry , casein , aromatic amino acids , lysine
Summary Five balance experiments on growing pigs were carried out to study the marginal efficiency of utilization of isoleucine, leucine, valine, histidine and phenylalanine + tyrosine and to estimate their requirements for maintenance. Purified diets based on casein and crystalline amino acids as the sole source of N contained graded levels of each amino acid, corresponding to protein accretion rates of 0, 33, 66, 99 and 132 g/day, respectively. All other essential amino acids were given in a 30% excess. N retention increased linearly (p < 0.01) as the dietary concentration of the limiting amino acid increased. Based on linear regression equations relating amino acid deposition in body protein to amino acid intake, marginal efficiencies of ileal digestible amino acid utilization were calculated to be isoleucine – 0.81, leucine – 0.81, valine – 0.82, histidine – 1.17 and phenylalanine + tyrosine – 0.67. Extrapolating the regression equations to zero N retention, the daily requirements of amino acids for N equilibrium were estimated to be (mg/kg 0.75 ) isoleucine – 18, leucine – 33, valine – 23, histidine – 14 and phenylalanine + tyrosine – 43.