Growth and Clinical Variables in Nitrogen-Restricted Piglets Fed an Adjusted Essential Amino Acid Mix: Effects of Partially Intact Protein-Based Diets

Paivi S. Worsoe, Per T. Sangild, Johannes B. van Goudoever, Berthold Koletzko, Eline M. van der Beek, Marieke Abrahamse-Berkeveld, Douglas G. Burrin, Bert J. M. van de Heijning, Thomas Thymann*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

4 Citations (Scopus)


Background: Current recommendations for protein levels in infant formula are intended to ensure that growth matches or exceeds growth of breastfed infants, but may provide a surplus of amino acids (AAs). Recent infant studies with AA-based formulas support specific adjustment of the essential amino acid (EAA) composition allowing for potential lowering of total protein levels. With the use of a combination of intact protein and free EAAs, we designed a formula that meets these adjusted EAA requirements for infants.

Objective: Our objective was to test whether this adjusted formula is safe and supports growth in a protein-restricted piglet model, and whether it shows better growth than an isonitrogenous formula based on free AAs.

Methods: Term piglets (Landrace x Yorkshire x Duroc, n = 72) were fed 1 of 4 isoenergetic formulas containing 70% intact protein and 30% of an EAA mixture or a complete AA-based control for 20 d: standard formula (ST-100), ST-100 with 25% reduction in proteinaceous nitrogen (ST-75), ST-75 with an adjusted EAA composition (O-75), or a diet as O-75, given as a complete AA-based diet (O-75AA).

Results: After an initial adaptation period, ST-75 and O-75 pigs showed similar growth rates, both lower than ST-100 pigs (similar to 25 compared with 31 g . kg(-1) . d(-1), respectively). The O-75AA pigs showed further reduced growth rate (15 g . kg(-1) . d(-1)) and fat proportion (both P <0.05, relative to O-75).

Conclusions: Formula based partly on intact protein is superior to AA-based formula in this experimental setting. The 25% lower, but EAA-adjusted, partially intact protein-based formula resulted in similar weight gain with a concomitant increased AA catabolism, compared with the standard 25% lower standard formula in artificially reared, protein-restricted piglets. Further studies should investigate if and how the specific EAA adjustments that allow for lowering of total protein levels will affect growth and body composition development in formula-fed infants.

Original languageEnglish
Pages (from-to)1118-1125
Number of pages8
JournalThe Journal of Nutrition
Issue number7
Publication statusPublished - 1-Jul-2018


  • formula
  • growth
  • development
  • amino acid
  • pig
  • infant
  • low protein formula
  • LIFE
  • PIGS

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