Dietary protein hydrolysates vs. the intact proteins do not enhance mucosal integrity and growth performance in weaned piglets

Two separate experiments, but using the same diets, were designed to study whether the addition to the diet of protein hydrolysates or crystalline glutamine (gln) affect small intestinal integrity (experiment 1) and growth performance (experiment 2). It was hypothesized that dietary supplementation of hydrolysed proteins would increase the availability of amino acids for the gut wall and therefore result in an improved small intestinal integrity and growth performance of piglets after weaning. The five diets differed in their protein composition: soybean meal and wheat gluten (SBM+WG), SBM and hydrolysed wheat gluten (SBM +HWG), hydrolysed soybean meal and WG (HSBM+WG), SBM and potato protein (SBM+PP), 2% of gln added to SBM and PP (SBM+PP+gln). In experiment 1, 88 piglets of 8.4 kg (S.D.: 0.82) were weaned at 26 days of age (day 0). Piglets were dissected and sampled on days 0, 3, or 7 postweaning. Results showed that the protein hydrolysates did not increase villus height, did not reduce crypt depth and did not raise brush-border aminopeptidase and isomaltase-sucrase activity when compared to the diets containing the unhydrolysed proteins. In experiment 2, 165 piglets of 8.5 kg (S.D.: 1.33) were weaned at 26 days of age. Feed intake and weight gain were not enhanced by the protein hydrolysates. The addition to the diet of crystalline gln resulted in improved average daily gain and feed efficiency by 22 and 17%, respectively (P<0.05) when compared to the other diets and measured during the first 2 weeks postweaning. Gln did not influence growth performance during days 0-7 postweaning. The feeding of protein hydrolysates led to more non-consistent faeces when compared to the SBM+WG diet (P<0.05). In conclusion, dietary supplementation of protein hydrolysates did not ameliorate the weaning-induced compromise of small intestinal integrity and did not enhance growth performance. Dietary supplementation of gln did not affect villus architecture during the 1st week postweaning, but it enhanced growth performance during the 2nd week. © 2003 Elsevier B.V. All rights reserved.