Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen

C Atasoglu, C Valdés, C J Newbold, R J Wallace

Research output: Contribution to journalArticleResearchpeer-review

36 Citations (Scopus)

Abstract

The influence of different N sources on fermentation rate and de novo amino acid synthesis by rumen micro-organisms was investigated in vitro using rumen fluid taken from four sheep receiving a mixed diet comprising (g/kg DM): grass hay 500, barley 299.5, molasses 100, fish meal 91, minerals and vitamins 9.5. Pancreatic casein hydrolysate (P; comprising mainly peptides with some free amino acids; 10 g/l), free amino acids (AA; casein acid hydrolysate + added cysteine and tryptophan; 10 g/l), or a mixture of L-proline, glycine, L-valine and L-threonine (M; 0.83 g/l each) were added to diluted (1:3, v/v), strained rumen fluid along with 15NH4Cl (A; 1.33 g/l) and 6.7 g/l of a mixture of starch, cellobiose and xylose (1:1:1, by weight). P and AA, but not M, stimulated net gas production after 4 and 8 h incubation (P < 0.05) in comparison with A alone. P increased microbial-protein synthesis (P < 0.05) compared with the other treatments. All of the microbial-N formed after 10 h was synthesized de novo from 15NH3 in treatment A, and the addition of pre-formed amino acids decreased the proportion to 0.37, 0.55, and 0.86 for P, AA, and M respectively. De novo synthesis of amino acids (0.29, 0.42 and 0.69 respectively) was lower than cell-N. Enrichment of alanine, glutamate and aspartate was slightly higher than that of other amino acids, while enrichment in proline was much lower, such that 0.83-0.95 of all proline incorporated into particulate matter was derived from pre-formed proline. Glycine, methionine, lysine, valine and threonine tended to be less enriched than other amino acids. The form in which the amino acids were supplied, as P or AA, had little influence on the pattern of de novo synthesis. When the concentration of peptides was decreased, the proportion of microbial-N formed from NH3 increased, so that at an initial concentration of 1 g peptides/l, similar to the highest reported ruminal peptide concentrations, 0.68 of cell-N was formed from NH3. Decreasing the NH3 concentration at 1.0 g peptides/l caused proportionate decreases in the fraction of cell-N derived from NH3, from 0.81 at 0.53 g NH3-N/l to 0.40 at 0.19 g NH3-N/l. It was concluded that different individual amino acids are synthesized de novo to different extents by mixed rumen micro-organisms when pre-formed amino acids are present, and that the source of N used for synthesis of cell-N and amino acids depends on the respective concentrations of the different N sources available; however, supplementing only with amino acids whose synthesis is lowest when pre-formed amino acids are present does not stimulate fermentation or microbial growth.

Original languageEnglish
Pages (from-to)307-14
Number of pages8
JournalBritish Journal of Nutrition
Volume81
Issue number4
Publication statusPrint publication - Apr 1999
Externally publishedYes

Fingerprint

Rumen
Fermentation
Sheep
Amino Acids
Peptides
Proline
Valine
Threonine
Glycine
Molasses
Cellobiose
Particulate Matter
Xylose
Hordeum
Poaceae
Aspartic Acid
Vitamins
Tryptophan
Alanine
Methionine

Keywords

  • Amino Acids/biosynthesis
  • Ammonia/metabolism
  • Animal Feed
  • Animals
  • Bacteria/metabolism
  • Bacterial Proteins/biosynthesis
  • Dietary Supplements
  • Fermentation
  • Nitrogen/metabolism
  • Peptides/pharmacology
  • Rumen/microbiology
  • Sheep

Cite this

@article{3e79b6f7b248493fbf796b0aaeef9732,
title = "Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen",
abstract = "The influence of different N sources on fermentation rate and de novo amino acid synthesis by rumen micro-organisms was investigated in vitro using rumen fluid taken from four sheep receiving a mixed diet comprising (g/kg DM): grass hay 500, barley 299.5, molasses 100, fish meal 91, minerals and vitamins 9.5. Pancreatic casein hydrolysate (P; comprising mainly peptides with some free amino acids; 10 g/l), free amino acids (AA; casein acid hydrolysate + added cysteine and tryptophan; 10 g/l), or a mixture of L-proline, glycine, L-valine and L-threonine (M; 0.83 g/l each) were added to diluted (1:3, v/v), strained rumen fluid along with 15NH4Cl (A; 1.33 g/l) and 6.7 g/l of a mixture of starch, cellobiose and xylose (1:1:1, by weight). P and AA, but not M, stimulated net gas production after 4 and 8 h incubation (P < 0.05) in comparison with A alone. P increased microbial-protein synthesis (P < 0.05) compared with the other treatments. All of the microbial-N formed after 10 h was synthesized de novo from 15NH3 in treatment A, and the addition of pre-formed amino acids decreased the proportion to 0.37, 0.55, and 0.86 for P, AA, and M respectively. De novo synthesis of amino acids (0.29, 0.42 and 0.69 respectively) was lower than cell-N. Enrichment of alanine, glutamate and aspartate was slightly higher than that of other amino acids, while enrichment in proline was much lower, such that 0.83-0.95 of all proline incorporated into particulate matter was derived from pre-formed proline. Glycine, methionine, lysine, valine and threonine tended to be less enriched than other amino acids. The form in which the amino acids were supplied, as P or AA, had little influence on the pattern of de novo synthesis. When the concentration of peptides was decreased, the proportion of microbial-N formed from NH3 increased, so that at an initial concentration of 1 g peptides/l, similar to the highest reported ruminal peptide concentrations, 0.68 of cell-N was formed from NH3. Decreasing the NH3 concentration at 1.0 g peptides/l caused proportionate decreases in the fraction of cell-N derived from NH3, from 0.81 at 0.53 g NH3-N/l to 0.40 at 0.19 g NH3-N/l. It was concluded that different individual amino acids are synthesized de novo to different extents by mixed rumen micro-organisms when pre-formed amino acids are present, and that the source of N used for synthesis of cell-N and amino acids depends on the respective concentrations of the different N sources available; however, supplementing only with amino acids whose synthesis is lowest when pre-formed amino acids are present does not stimulate fermentation or microbial growth.",
keywords = "Amino Acids/biosynthesis, Ammonia/metabolism, Animal Feed, Animals, Bacteria/metabolism, Bacterial Proteins/biosynthesis, Dietary Supplements, Fermentation, Nitrogen/metabolism, Peptides/pharmacology, Rumen/microbiology, Sheep",
author = "C Atasoglu and C Vald{\'e}s and Newbold, {C J} and Wallace, {R J}",
year = "1999",
month = "4",
language = "English",
volume = "81",
pages = "307--14",
journal = "British Journal of Nutrition",
issn = "0007-1145",
publisher = "Cambridge University Press",
number = "4",

}

Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen. / Atasoglu, C; Valdés, C; Newbold, C J; Wallace, R J.

In: British Journal of Nutrition, Vol. 81, No. 4, 04.1999, p. 307-14.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen

AU - Atasoglu, C

AU - Valdés, C

AU - Newbold, C J

AU - Wallace, R J

PY - 1999/4

Y1 - 1999/4

N2 - The influence of different N sources on fermentation rate and de novo amino acid synthesis by rumen micro-organisms was investigated in vitro using rumen fluid taken from four sheep receiving a mixed diet comprising (g/kg DM): grass hay 500, barley 299.5, molasses 100, fish meal 91, minerals and vitamins 9.5. Pancreatic casein hydrolysate (P; comprising mainly peptides with some free amino acids; 10 g/l), free amino acids (AA; casein acid hydrolysate + added cysteine and tryptophan; 10 g/l), or a mixture of L-proline, glycine, L-valine and L-threonine (M; 0.83 g/l each) were added to diluted (1:3, v/v), strained rumen fluid along with 15NH4Cl (A; 1.33 g/l) and 6.7 g/l of a mixture of starch, cellobiose and xylose (1:1:1, by weight). P and AA, but not M, stimulated net gas production after 4 and 8 h incubation (P < 0.05) in comparison with A alone. P increased microbial-protein synthesis (P < 0.05) compared with the other treatments. All of the microbial-N formed after 10 h was synthesized de novo from 15NH3 in treatment A, and the addition of pre-formed amino acids decreased the proportion to 0.37, 0.55, and 0.86 for P, AA, and M respectively. De novo synthesis of amino acids (0.29, 0.42 and 0.69 respectively) was lower than cell-N. Enrichment of alanine, glutamate and aspartate was slightly higher than that of other amino acids, while enrichment in proline was much lower, such that 0.83-0.95 of all proline incorporated into particulate matter was derived from pre-formed proline. Glycine, methionine, lysine, valine and threonine tended to be less enriched than other amino acids. The form in which the amino acids were supplied, as P or AA, had little influence on the pattern of de novo synthesis. When the concentration of peptides was decreased, the proportion of microbial-N formed from NH3 increased, so that at an initial concentration of 1 g peptides/l, similar to the highest reported ruminal peptide concentrations, 0.68 of cell-N was formed from NH3. Decreasing the NH3 concentration at 1.0 g peptides/l caused proportionate decreases in the fraction of cell-N derived from NH3, from 0.81 at 0.53 g NH3-N/l to 0.40 at 0.19 g NH3-N/l. It was concluded that different individual amino acids are synthesized de novo to different extents by mixed rumen micro-organisms when pre-formed amino acids are present, and that the source of N used for synthesis of cell-N and amino acids depends on the respective concentrations of the different N sources available; however, supplementing only with amino acids whose synthesis is lowest when pre-formed amino acids are present does not stimulate fermentation or microbial growth.

AB - The influence of different N sources on fermentation rate and de novo amino acid synthesis by rumen micro-organisms was investigated in vitro using rumen fluid taken from four sheep receiving a mixed diet comprising (g/kg DM): grass hay 500, barley 299.5, molasses 100, fish meal 91, minerals and vitamins 9.5. Pancreatic casein hydrolysate (P; comprising mainly peptides with some free amino acids; 10 g/l), free amino acids (AA; casein acid hydrolysate + added cysteine and tryptophan; 10 g/l), or a mixture of L-proline, glycine, L-valine and L-threonine (M; 0.83 g/l each) were added to diluted (1:3, v/v), strained rumen fluid along with 15NH4Cl (A; 1.33 g/l) and 6.7 g/l of a mixture of starch, cellobiose and xylose (1:1:1, by weight). P and AA, but not M, stimulated net gas production after 4 and 8 h incubation (P < 0.05) in comparison with A alone. P increased microbial-protein synthesis (P < 0.05) compared with the other treatments. All of the microbial-N formed after 10 h was synthesized de novo from 15NH3 in treatment A, and the addition of pre-formed amino acids decreased the proportion to 0.37, 0.55, and 0.86 for P, AA, and M respectively. De novo synthesis of amino acids (0.29, 0.42 and 0.69 respectively) was lower than cell-N. Enrichment of alanine, glutamate and aspartate was slightly higher than that of other amino acids, while enrichment in proline was much lower, such that 0.83-0.95 of all proline incorporated into particulate matter was derived from pre-formed proline. Glycine, methionine, lysine, valine and threonine tended to be less enriched than other amino acids. The form in which the amino acids were supplied, as P or AA, had little influence on the pattern of de novo synthesis. When the concentration of peptides was decreased, the proportion of microbial-N formed from NH3 increased, so that at an initial concentration of 1 g peptides/l, similar to the highest reported ruminal peptide concentrations, 0.68 of cell-N was formed from NH3. Decreasing the NH3 concentration at 1.0 g peptides/l caused proportionate decreases in the fraction of cell-N derived from NH3, from 0.81 at 0.53 g NH3-N/l to 0.40 at 0.19 g NH3-N/l. It was concluded that different individual amino acids are synthesized de novo to different extents by mixed rumen micro-organisms when pre-formed amino acids are present, and that the source of N used for synthesis of cell-N and amino acids depends on the respective concentrations of the different N sources available; however, supplementing only with amino acids whose synthesis is lowest when pre-formed amino acids are present does not stimulate fermentation or microbial growth.

KW - Amino Acids/biosynthesis

KW - Ammonia/metabolism

KW - Animal Feed

KW - Animals

KW - Bacteria/metabolism

KW - Bacterial Proteins/biosynthesis

KW - Dietary Supplements

KW - Fermentation

KW - Nitrogen/metabolism

KW - Peptides/pharmacology

KW - Rumen/microbiology

KW - Sheep

M3 - Article

VL - 81

SP - 307

EP - 314

JO - British Journal of Nutrition

JF - British Journal of Nutrition

SN - 0007-1145

IS - 4

ER -