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Title: Growth and clinical variables in nitrogen-restricted piglets fed an adjusted essential amino acid mix: Effects using partially intact protein-based diets

Author
item WORSOE, PAIVI - University Of Copenhagen
item SANGILD, PER - University Of Copenhagen
item VAN GOUDOEVER, JOHANNES - Vu University Medical Center
item KOLETZKO, BERTHOLD - Ludwig-Maximilians University
item VAN DER BEEK, ELINE - Utrecht University
item ABRAHAMSE-BERKEVELD, MARIEKE - Utrecht University
item Burrin, Douglas - Doug
item VAN DE HEIJNING, BERT J.M. - Utrecht University
item THYMANN, THOMAS - University Of Copenhagen

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2018
Publication Date: 7/1/2018
Citation: Worsoe, P.S., Sangild, P.T., Van Goudoever, J.B., Koletzko, B., Van Der Beek, E.M., Abrahamse-Berkeveld, M., Burrin, D.G., Van De Heijning, B., Thymann, T. 2018. Growth and clinical variables in nitrogen-restricted piglets fed an adjusted essential amino acid mix: Effects using partially intact protein-based diets. Journal of Nutrition. 148(7):1118-1125. http://doi.org/10.1093/jn/nxy073
DOI: https://doi.org/10.1093/jn/nxy073

Interpretive Summary: The protein and amino acid requirements for human infants is based on their concentration in human milk. However, most infant formulas contain much higher protein levels than human milk. Recent studies have implicated that the higher protein intake from infant formula may result in accelerated weight gain in infancy that leads to increased risk for metabolic disease later in life, such as obesity. We recently tested this concept in neonatal pigs and showed that lower protein, free amino acid-based formulas may be safe to support normal growth and more efficient use of protein. In the current study, we used neonatal pigs to test whether a marginally lower (25%) protein and optimal amino acid formula can support normal growth when the formulas contain intact protein but are supplemented with small amount (30%) of free essential amino acids. Our results showed that pigs grow faster over a three week period when fed intact protein-versus free amino acid-based formulas. However, in intact-protein based formulas, pigs fed marginally lower protein grew slower than those fed normal protein, even when the essential amino acid composition was optimized.

Technical Abstract: Current recommendations for protein levels in infant formula ensure that growth matches or exceeds growth of breast-fed infants, but may provide a surplus of amino acids (AA). Recent studies in infants using AA-based formulas support specific adjustment of the essential AA (EAA) composition allowing for potential lowering of total protein levels. Using a combination of intact protein and free EAA, we designed a formula that meets these adjusted EAA requirements for infants. 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 AA. Term piglets (Landrace x Yorkshire x Duroc, n=72) were fed one of four isoenergetic formulas containing 70% intact protein and 30% of an EAA mixture or a complete AA-based control for 20 days: 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). After an initial adaptation period, ST-75 and O-75 pigs showed similar growth rates, both lower than ST-100 pigs (about 25 versus 31 g/(kg.d), respectively). The O-75AA pigs showed further reduced growth rate (15 g/(kg.d)) and fat proportion (both P is less than 0.05, relative to O-75). In conclusion, 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.