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

Background: Excess protein intake in early life has been linked to obesity and metabolic syndrome in later life. Yet protein, and in particular the essential amino acids (EAAs), need to be present in adequate quantity to support growth. Objective: With the use of a piglet model restricted in dietary amino acids (AAs), we compared the efficacy and safety of a standard formula with a low-AA formula containing an adjusted AA composition. Methods: Female piglets (3-7 d old; Landrace × Yorkshire × Duroc) were fed 1 of 4 isoenergetic AA-based formulas for 14 d (700 kJ · kg body weight-1 · d-1). The formulas contained a set control amount (44 g/L) and AA compositions referred to as the experimental standard (ST-100, n = 22), or 20% or 50% lower total AAs (respectively, ST-80, n = 19 and ST-50, n = 13), or 20% lower total AAs with an optimally adjusted EAA composition (O-80, n = 17). A series of clinical and paraclinical endpoints were measured. Results: Growth rates were similar for ST-100, O-80 and ST-80 piglets (all ∼15 g · kg-1 · d-1), whereas ST-50 had a markedly lower weight gain relative to all groups (all P < 0.05). Relative to ST-100, all groups with reduced AA intake showed ∼16% reduction in plasma albumin and ∼30% reduction in plasma urea (both P < 0.05). The absolute leucine oxidation rate was ∼30% lower for O-80 than for ST-100 piglets (P < 0.05). Conclusions: These data show that a 20% reduction in total AA intake for both the control (ST-80) and the adjusted AA (O-80) formula did not have any short-term adverse effects on growth in artificially reared, AA-restricted piglets. The lower absolute leucine oxidation rate observed in O-80 supports the development of an infant formula with an improved AA composition and a moderate reduction in total protein to support adequate growth in healthy infants.

Corn-Soy-Blend Fortified with Phosphorus to Prevent Refeeding Hypophosphatemia in Undernourished Piglets.

BACKGROUND: Phosphorus (P) levels in refeeding diets are very important as undernourished children are at risk of hypophosphatemia during refeeding. For this reason, conventional corn-soy-blends (CSB) have been reformulated by the World Food Programme to obtain a mono-calcium-phosphate fortified product (CSB+) and a product further fortified with skim milk powder (CBS++). METHODS: Using a piglet model of undernourished children, we hypothesized that feeding of CSB+, CSB++ or CSB+ with added whey permeate (CSB+/wp) would help to prevent refeeding hypophosphatemia. Pigs were weaned at 4 weeks of age and undernutrition was induced with a nutritionally inadequate pure maize diet for 7 weeks, after which they were refed for 3 weeks with either CSB+ (n = 10), CSB++ (n = 10) or CSB+/wp (n = 10). For reference, a fourth group continued on the maize diet (REF, n = 10). RESULTS: Following induction of undernutrition, body weight and length were 29±5% and 67±4% (means±SD) of values in age-matched pigs fed a nutritionally adequate diet, and the mean serum P level was 1.77±0.34 mmol/l. During the first week of refeeding, P levels in the CSB+ pigs decreased to 55% of values before refeeding (P < 0.05) while values in the CSB++ and CSB+/wp pigs were able to maintain their plasma phosphate at a similar level as before refeeding. CONCLUSION: We conclude that fortification of CSB with only monocalcium-phosphate does not prevent hypophosphatemia. Dairy products like skim milk powder or whey permeate may represent relevant sources of phosphorus during refeeding. The content and form of phosphorus in such diets need to be carefully evaluated, and the undernourished piglet may be used to test the efficacy of such diets.

Cardiac Dysfunction in a Porcine Model of Pediatric Malnutrition.

BACKGROUND: Half a million children die annually of severe acute malnutrition and cardiac dysfunction may contribute to the mortality. However, cardiac function remains poorly examined in cases of severe acute malnutrition. OBJECTIVE: To determine malnutrition-induced echocardiographic disturbances and longitudinal changes in plasma pro-atrial natriuretic peptide and cardiac troponin-T in a pediatric porcine model. METHODS AND RESULTS: Five-week old piglets (Duroc-x-Danish Landrace-x-Yorkshire) were fed a nutritionally inadequate maize-flour diet to induce malnutrition (MAIZE, n = 12) or a reference diet (AGE-REF, n = 12) for 7 weeks. Outcomes were compared to a weight-matched reference group (WEIGHT-REF, n = 8). Pro-atrial natriuretic peptide and cardiac troponin-T were measured weekly. Plasma pro-atrial natriuretic peptide decreased in both MAIZE and AGE-REF during the first 3 weeks but increased markedly in MAIZE relative to AGE-REF during week 5-7 (p ≤ 0.001). There was overall no difference in plasma cardiac troponin-T between groups. However, further analysis revealed that release of cardiac troponin-T in plasma was more frequent in AGE-REF compared with MAIZE (OR: 4.8; 95%CI: 1.2-19.7; p = 0.03). However, when release occurred, cardiac troponin-T concentration was 6.9-fold higher (95%CI: 3.0-15.9; p < 0.001) in MAIZE compared to AGE-REF. At week 7, the mean body weight in MAIZE was lower than AGE-REF (8.3 vs 32.4 kg, p < 0.001), whereas heart-weight relative to body-weight was similar across the three groups. The myocardial performance index was 86% higher in MAIZE vs AGE-REF (p < 0.001) and 27% higher in MAIZE vs WEIGHT-REF (p = 0.025). CONCLUSIONS: Malnutrition associates with cardiac dysfunction in a pediatric porcine model by increased myocardial performance index and pro-atrial natriuretic peptide and it associates with cardiac injury by elevated cardiac troponin-T. Clinical studies are needed to see if the same applies for children suffering from malnutrition.

Antibiotics modulate intestinal immunity and prevent necrotizing enterocolitis in preterm neonatal piglets.

Preterm birth, bacterial colonization, and formula feeding predispose to necrotizing enterocolitis (NEC). Antibiotics are commonly administered to prevent sepsis in preterm infants, but it is not known whether this affects intestinal immunity and NEC resistance. We hypothesized that broad-spectrum antibiotic treatment improves NEC resistance and intestinal structure, function, and immunity in neonates. Caesarean-delivered preterm pigs were fed 3 days of parenteral nutrition followed by 2 days of enteral formula. Immediately after birth, they were assigned to receive either antibiotics (oral and parenteral doses of gentamycin, ampicillin, and metronidazole, ANTI, n = 11) or saline in the control group (CON, n = 13), given twice daily. NEC lesions and intestinal structure, function, microbiology, and immunity markers were recorded. None of the ANTI but 85% of the CON pigs developed NEC lesions by day 5 (0/11 vs. 11/13, P < 0.05). ANTI pigs had higher intestinal villi (+60%), digestive enzyme activities (+53-73%), and goblet cell densities (+110%) and lower myeloperoxidase (-51%) and colonic microbial density (10(5) vs. 10(10) colony-forming units, all P < 0.05). Microarray transcriptomics showed strong downregulation of genes related to inflammation and innate immune response to microbiota and marked upregulation of genes related to amino acid metabolism, in particular threonine, glucose transport systems, and cell cycle in 5-day-old ANTI pigs. In a follow-up experiment, 5 days of antibiotics prevented NEC at least until day 10. Neonatal prophylactic antibiotics effectively reduced gut bacterial load, prevented NEC, intestinal atrophy, dysfunction, and inflammation and enhanced expression of genes related to gut metabolism and immunity in preterm pigs.

Malnutrition induces gut atrophy and increases hepatic fat infiltration: studies in a pig model of childhood malnutrition.

Childhood malnutrition is a problem in developing countries, and pathological changes in digestive organs such as the intestine and liver are poorly understood. An animal model to study the progression of severe acute malnutrition could elucidate pathological changes in the intestine and liver. We sought to characterize growth and clinical changes during malnutrition related to structural and functional indices in the intestine and liver. Newly weaned piglets were given ad libitum access to a maize flour diet (MAIZE, n=9) or a nutritionally optimized reference diet (REFERENCE, n=12) for 7 weeks. Growth, hematology and clinical biochemistry where recorded weekly. After 7 weeks, the MAIZE pigs had lower body weights than the REF pigs (8.3 kg vs. 32.4 kg, P < 0.001), indicating severe stunting and moderate to severe wasting. This was paralleled by lower values for hematocrit, hemoglobin and mean cell volume in MAIZE vs. REFERENCE (P < 0.01), indicating anemia. Although the observed temporal changes in MAIZE were associated with atrophy of the small intestinal mucosa (P < 0.001), digestive enzyme activity was only marginally reduced. Serum alanine aminotransferase, bilirubin and albumin were increased in the MAIZE pigs (P < 0.001), and the liver had a vacuolated appearance and tendency toward increased triglyceride content (P=0.054). We conclude that liver and intestinal indices are compromised during malnutrition and are associated with temporal changes in growth and hematological and biochemical endpoints. The pig model is relevant for malnourished infants and can act as a valuable tool for understanding the pathophysiology of malnutrition.

Similar efficacy of human banked milk and bovine colostrum to decrease incidence of necrotizing enterocolitis in preterm piglets.

Preterm birth and formula feeding predispose to necrotizing enterocolitis (NEC) in infants. As mother's milk is often absent following preterm delivery, infant formula (IF) and human donor milk (HM) are frequently used as alternatives. We have previously shown that porcine and bovine colostrum (BC) provide similar NEC protection in preterm piglets relative to IF. We hypothesized that HM exerts similar effects and that this effect is partly species-independent. Preterm piglets (n = 40) received 2 days of total parenteral nutrition, followed by a rapid transition to full enteral feeding (15 ml·kg(-1)·2 h(-1)) for 2 days using BC (n = 13), HM (n = 13), or IF (n = 14). Intestinal passage time and hexose absorption were tested in vivo. Body and organ weights were recorded on day 5, and macroscopic NEC lesions in the gastrointestinal tract were assessed. Intestinal samples were collected for determination of histomorphology, histopathology, tissue IL-6 and IL-8, organic acids, bacterial adherence by fluorescence in situ hybridization score, and digestive enzyme activities. Relative to IF, pigs from BC and HM showed longer intestinal passage time; higher weight gain, hexose absorptive capacity, mucosal proportion, and enzyme activities; lower NEC incidence, organic acid concentration, and IL-8 concentration; and reduced histopathology lesions. Tissue IL-6 concentration and bacterial adherence score were lower for HM, relative to both BC and IF groups. We conclude that BC and HM are both superior to IF in stimulating gut structure, function, and NEC resistance in preterm piglets. BC may be a relevant alternative to HM when mother's milk is unavailable during the first week after preterm birth.