A Casein Hydrolysate Does Not Enhance Ileal Endogenous Protein Flows Compared With the Parent Intact Casein When Fed to Growing Pigs
Résumé
Background: The form of dietary nitrogen (free peptides or intact proteins) may influence the
amount of endogenous amino acids found at the terminal ileum of the pig, and it has been
speculated that hydrolyzed dietary protein may lead to increased endogenous amino acids.
Objective: To compare the effect of dietary free peptides on ileal endogenous nitrogen and
amino acid flows [ileal endogenous nitrogen flow (ENFL), ileal endogenous amino acid flow
(EAAFL)] with that of peptides released naturally from dietary protein during digestion, from the
same intact parent protein source.
Methods: Six pigs (mean body weight: 34 kg) were equipped with a postvalve T-caecum cannula.
Semisynthetic test diets contained the same 15N-labeled intact casein (C) or hydrolyzed casein
(HC). Pigs received the test diets every sixth day and the corresponding unlabeled diets in the
intervening 5-d periods. Digesta were pooled from 4 to 10 h postprandially. EAAFL and ENFL,
calculated with reference to the dietary marker titanium dioxide, were determined by isotope
dilution for C and HC.
Results: Ileal EAAFL and ENFL (mean flows n = 5 of 1828 and 1912 μg/g of dry matter intake for
diets HC and C, respectively) did not differ (P > 0.05) between pigs fed HC and C. Centrifugation
and ultrafiltration of the HC digesta allowed an estimation of label recycling into gut endogenous
proteins. Some 20% of ileal endogenous protein (diet HC, ultrafiltered digesta) was 15N-labeled
due to tracer recycling.
Conclusions: The administration of a casein hydrolysate had no effect on ileal endogenous protein
flows compared with C. There was no evidence of enhanced ileal endogenous protein losses with
the HC diet.
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