An effect of dietary protein content on endogenous ileal lysine flow in the growing rat

Hodgkinson, Suzanne M.; Moughan, Paul J.

doi:10.1002/jsfa.2701

Cited by 12 publications

(7 citation statements)

References 16 publications

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“…The gradient protein method depends on the theory that true AA digestibility is independent of the dietary CP level [ 2 , 14 ]. Based on several previous studies [ 24 – 26 ], we assumed that variation in the dietary CP levels within a small range had little effect on the EAALs. A study in pigs fed diets with equal graded protein levels of 4% found no significant differences in the EAALs among the adjacent CP levels.…”

Section: Discussionmentioning

confidence: 99%

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The 15N-leucine single-injection method allows for determining endogenous losses and true digestibility of amino acids in cecectomized roosters

Soomro

et al. 2017

PLoS ONE

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This study was conducted to assess the influence of dietary protein content in poultry when using the 15N-leucine single-injection method to determine endogenous amino acid losses (EAALs) in poultry. Forty-eight cecectomized roosters (2.39 ± 0.23 kg) were randomly allocated to eight dietary treatments containing protein levels of 0, 3%, 6%, 9%, 12%, 15%, 18% and 21%. Each bird was precisely fed an experimental diet of 25 g/kg of body weight. After feeding, all roosters were subcutaneously injected with a 15N-leucine solution at a dose of 20 mg/kg of body weight. Blood was sampled 23 h after the injection, and excreta samples were continuously collected during the course of the 48-h experiment. The ratio of 15N-enrichment of leucine in crude mucin to free leucine in plasma ranged from 0.664 to 0.763 and remained relatively consistent (P > 0.05) across all treatments. The amino acid (AA) profiles of total endogenous AAs, except isoleucine, alanine, aspartic acid, cysteine, proline and serine, were not influenced (P > 0.05) by dietary protein contents. The predominant endogenous AAs in the excreta were glutamic acid, aspartic acid, threonine, serine and proline. The order of the relative proportions of these predominant AAs also remained relatively constant (P > 0.05). The endogenous losses of total AAs determined with the 15N-leucine single-injection method increased curvilinearly with the dietary protein contents. The true digestibility of most AAs and total AAs was independent of their respective dietary protein levels. Collectively, the 15N-leucine single-injection method is appropriate for determining EAALs and the true digestibility of AAs in poultry fed varying levels of protein-containing ingredients.

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Section: Discussionmentioning

confidence: 99%

“…Based on several previous studies [ 24 – 26 ], we assumed that the dietary CP levels, which varied within a small range (3%), had little effect on the EAALs.…”

Section: Methodsmentioning

confidence: 99%

The 15N-leucine single-injection method allows for determining endogenous losses and true digestibility of amino acids in cecectomized roosters

Soomro

et al. 2017

PLoS ONE

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“…However, when the pig received a high-protein diet (20% EHC, 1000-5000 Da), more comparable to the protein levels of the cat and dog diets, it also had a higher endogenous ileal total nitrogen loss (see Table 2, reference 45). A dose-response effect of dietary peptides on gut endogenous amino acid loss has been documented (44,45).…”

Section: Experimental Evidence For An Effect Of Dietary Peptides On Omentioning

confidence: 99%

Food-Derived Bioactive Peptides Influence Gut Function

Moughan

Fuller²,

Han³

et al. 2007

International Journal of Sport Nutrition and Exercise Metabolism

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Bioactive peptides either present in foods or released from food proteins during digestion have a wide range of physiological effects, including on gut function. Many of the bioactive peptides characterized to date that influence gut motility, secretion, and absorption are opioid agonists or antagonists. The authors review a body of experimental evidence that demonstrates an effect of peptides from food proteins on endogenous (nondietary) protein flow at the terminal ileum of simple-stomached mammals, including adult humans. At least some dietary peptides (1000-5000 Da) significantly enhance the loss of protein from the small intestine, causing an increased amount of protein to enter the colon. Food-derived peptides appear to either stimulate protein secretion into the gut lumen or inhibit amino acid reabsorption or influence both processes simultaneously. The effect of dietary peptides on small-intestine secretory-protein dynamics is discussed in the context of the major components of gut endogenous protein, sloughed cells, enzymatic secretions, mucin, and bacterial protein.

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“…The traditional technique involves feeding a protein-free diet ensuring that any amino acids present in ileal digesta must be of endogenous origin (de Lange et al 1989). However, the protein-free technique is flawed for a number of reasons (de Lange et al 1989), including the fact that the amount of endogenous protein present in the gastrointestinal tract is much greater when protein or peptides are present in the diet (Hodgkinson et al 2000;Hodgkinson and Moughan 2007). Consequently, while determining endogenous ileal amino acid losses in animals or humans given diets that contain protein is preferable, it raises the problem in that the protein/amino acids of endogenous origin must be distinguished from the undigested dietary protein/peptides and amino acids.…”

Section: Using Guanidination To Determine Endogenous Ileal Lysine Lossesmentioning

confidence: 98%

Use of the guanidination reaction for determining reactive lysine, bioavailable lysine and gut endogenous lysine

Rutherfurd

2015

Amino Acids

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Determining the bioavailability of lysine in foods and feedstuffs is important since lysine is often the first limiting indispensable amino acid in diets for intensively farmed livestock (pigs and poultry) and also in many cereal-based diets consumed by humans. When foods or feedstuffs are heat processed, lysine can undergo Maillard reactions to produce nutritionally unavailable products. The guanidination reaction, the reaction of O-methylisourea with the side chain amino group of lysine that produces homoarginine, has been used to determine the unmodified lysine (reactive lysine) in processed foods and feedstuffs and also true ileal digestible reactive lysine (bioavailable lysine). The advantages of the guanidination method in comparison with other reactive lysine methods such as the fluorodinitrobenzene, trinitrobenzenesulphonic acid and dye-binding methods are that it is very specific for reactive lysine and also that the method is relatively straightforward to conduct. The specificity of the guanidination reaction for the lysine side chain amino group is particularly important, since ileal digesta will contain N-terminal groups in the form of free amino acids and peptides. The main disadvantage is that complete conversion of lysine to homoarginine is required, yet it is not straightforward to test for complete guanidination in processed foods and feedstuffs. Another disadvantage is that the guanidination reaction conditions may vary for different food types and sometimes within the same food type. Consequently, food-specific guanidination reaction conditions may be required and more work is needed to optimise the reaction conditions across different foods and feedstuffs.

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An effect of dietary protein content on endogenous ileal lysine flow in the growing rat

Cited by 12 publications

References 16 publications

The 15N-leucine single-injection method allows for determining endogenous losses and true digestibility of amino acids in cecectomized roosters

The 15N-leucine single-injection method allows for determining endogenous losses and true digestibility of amino acids in cecectomized roosters

Food-Derived Bioactive Peptides Influence Gut Function

Use of the guanidination reaction for determining reactive lysine, bioavailable lysine and gut endogenous lysine

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