Growth, body composition and hormonal status of growing pigs exhibiting a normal or small weight at birth and exposed to a neonatal diet enriched in proteins

Branched-chain amino acid supplementation does not enhance lean tissue accretion in low birth weight neonatal pigs, despite lower Sestrin2 expression in skeletal muscle

Postnatal muscle growth is impaired in low birth weight (L) neonatal pigs. Leucine supplementation has been established as a dietary intervention to enhance muscle growth in growing animals. The aim of this study was to investigate the efficacy of supplementing L neonatal pig formulas with branched-chain amino acids (B) to enhance the rate of protein accretion. Twenty-four 3-day old pigs were divided into two groups low (L) and normal birth weight (N) based on weight at birth. Pigs were assigned to a control (C) or 1% branched-chain amino acids (B) formulas, and fed at 250 mL·kg body weight -1·d-1 for 28 d. Body weight of pigs in the L group was less than those in the N group (P < 0.01). However, fractional body weight was greater for L pigs compared with their N siblings from day 24 to 28 of feeding regardless of formula (P < 0.01). In addition, feed efficiency (P < 0.0001) and efficiently of protein accretion (P < 0.0001) were greater for L than N pigs regardless of supplementation. Pigs fed the B formula had greater plasma leucine, isoleucine, and valine concentrations compared with those fed the C formula (P < 0.05). Longissimus dorsi Sestrin2 protein expression was less for pigs in the L group compared with those in the N group (P < 0.01), but did not result in a corresponding increase in translation initiation signaling. Longissimus dorsi mRNA expression of BCAT2 was less for LB pigs compared with those in the LC group, and was intermediate for NC and NB pigs (P < 0.05). Hepatic mRNA expression of BCKDHA was greater for pigs in the L compared with those in the N groups (P < 0.05). However, plasma branched-chain keto-acid concentration was reduced for C compared with those in the B group (P < 0.05). These data suggest that branched-chain amino acid supplementation does not improve lean tissue accretion of low and normal birth weight pigs, despite a reduction in Sestrin2 expression in skeletal muscle of low birth weight pigs. The modest improvement in fractional growth rate of low birth weight pigs compared with their normal birth weight siblings was likely due to a more efficient dietary protein utilization.

Impact of macronutrient supplements on later growth of children born preterm or small for gestational age: A systematic review and meta-analysis of randomised and quasirandomised controlled trials

BACKGROUND

Nutritional supplements may improve short-term growth of infants born small (preterm or small for gestational age), but there are few data on long-term effects and concerns that body composition may be adversely affected. Effects also may differ between girls and boys. Our systematic review and meta-analysis assessed the effects of macronutrient supplements for infants born small on later growth.

METHODS AND FINDINGS

We searched OvidMedline, Embase, Cochrane CENTRAL, and Cochrane Database of Systematic Reviews from inception to January 30, 2020, and controlled-trials.com, clinicaltrials.gov, and anzctr.org.au on January 30, 2020. Randomised or quasirandomised trials were included if the intention was to increase macronutrient intake to improve growth or development of infants born small and growth was assessed after discharge. Primary outcome was body mass index (BMI) in childhood. Data were pooled using random-effect models. Outcomes were evaluated in toddlers (< 3 years), childhood (3 to 8 years), adolescence (9 to 18 years), and adulthood (>18 years). Forty randomised and 2 quasirandomised trials of variable methodological quality with 4,352 infants were included. Supplementation did not alter BMI in childhood (7 trials, 1,136 children; mean difference [MD] -0.10 kg/m2, [95% confidence interval (CI) -0.37 to 0.16], p = 0.45). In toddlers, supplementation increased weight (31 trials, 2,924 toddlers; MD 0.16 kg, [0.01 to 0.30], p = 0.03) and length/height (30 trials, 2,889 toddlers; MD 0.44 cm, [0.10 to 0.77], p = 0.01), but not head circumference (29 trials, 2,797 toddlers; MD 0.15 cm, [-0.03 to 0.33], p = 0.10). In childhood, there were no significant differences between groups in height (7 trials, 1,136 children; MD 0.22 cm, [-0.48 to 0.92], p = 0.54) or lean mass (3 trials, 354 children; MD -0.07 kg, [-0.98 to 0.85], p = 0.88), although supplemented children appeared to have higher fat mass (2 trials, 201 children; MD 0.79 kg, [0.19 to 1.38], p = 0.01). In adolescence, there were no significant differences between groups in BMI (2 trials, 216 adolescents; MD -0.48 kg/m2, [-2.05 to 1.08], p = 0.60), height (2 trials, 216 adolescents; MD -0.55 cm, [-2.95 to 1.86], p = 0.65), or fat mass (2 trials, 216 adolescents; MD -1.3 5 kg, [-5.76 to 3.06], p = 0.55). In adulthood, there also were no significant differences between groups in weight z-score (2 trials, 199 adults; MD -0.11, [-0.72 to 0.50], p = 0.73) and height z-score (2 trials, 199 adults; MD -0.07, [-0.36 to 0.22], p = 0.62). In subgroup analysis, supplementation was associated with increased length/height in toddler boys (2 trials, 173 boys; MD 1.66 cm, [0.75 to 2.58], p = 0.0003), but not girls (2 trials, 159 girls; MD 0.15 cm, [-0.71 to 1.01], p = 0.74). Limitations include considerable unexplained heterogeneity, low to very low quality of evidence, and possible bias due to low or unbalanced followup.

CONCLUSIONS

In this systematic review and meta-analysis, we found no evidence that early macronutrient supplementation for infants born small altered BMI in childhood. Although supplements appeared to increase weight and length in toddlers, effects were inconsistent and unlikely to be clinically significant. Limited data suggested that supplementation increased fat mass in childhood, but these effects did not persist in later life. PROSPERO registration: CRD42019126918.

Flaxseed oil supplementation improves intestinal function and immunity, associated with altered intestinal microbiome and fatty acid profile in pigs with intrauterine growth retardation

Flaxseed oil (FO), enriched in n-3 polyunsaturated fatty acids (PUFAs), is an important oil source for intestinal development and health. We aimed to study the different effects of FO versus soybean oil (SO) on growth, intestinal health and immune function of neonates with intrauterine growth retardation (IUGR) using a weaned piglet model. Forty pairs of male IUGR and normal birth weight piglets, weaned at 21 ± 1 d, were fed diets containing either 4% FO or SO for 3 weeks consecutively. Growth performance, nutrient digestibility and intestinal function parameters, immunology and microbiota composition were determined. IUGR led to a poor growth rate, nutrient digestibility and abnormal immunology variables, whereas feeding FO diet improved systemic and gut immunity, as indicated by increased plasma concentration of immunoglobulin G and decreased CD3+CD8+ T lymphocytes, and down-regulated intestinal expression of genes (MyD88, NF-κB, TNF-α, IL-10). Although IUGR tended to decrease villous height, feeding FO diet tended to increase the villi-crypt ratio and up-regulated expressions of tight junction genes (Claudin-1 and ZO-1), together with increased mucosa contents of n-3 PUFAs and a lower Σn-6/Σn-3 ratio. Besides, FO diet decreased the abundance of pathogenic bacteria Spirochaetes, and increased phylum Actinobacteria, and genera Blautia and Bifidobacterium in colonic digesta. Our findings indicate that IUGR impairs growth rate, nutrient digestibility, and partly immunology variables, whereas feeding FO-supplemented diet could improve intestinal function and immunity of both IUGR and NBW pigs, associated with the altered gut microbiome and mucosal fatty acid profile.

Effects of Birth Weight and Postnatal Nutritional Restriction on Skeletal Muscle Development, Myofiber Maturation, and Metabolic Status of Early-Weaned Piglets

Piglets with light weaning weight commonly have a slow post-weaning growth rate due to impaired skeletal muscle development. Therefore, the present study aimed to investigate the impact of birth weight and nutrient intake on skeletal muscle development, myofiber maturation, and metabolic status of early-weaned piglets. Twelve pairs of normal birth weight and intrauterine growth-retarded (IUGR) piglets (seven days old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake for 21 days. Serum and muscle samples were collected for further analysis. The results indicated that muscle weight, cross-sectional areas, and muscular glycogen were lower (p < 0.05) in both IUGR and restricted fed piglets. Nutrient restriction decreased the contents of RNA, the RNA to DNA ratio, and the percentages of myosin heavy chain (MyHC) IIx (p < 0.05), whereas increased the activity of β-hydroxy-acyl-CoA-dehydrogenase (HAD), the ratio of HAD to citrate synthase, as well as the percentages of MyHC I (p < 0.05). In addition, nutrient restriction significantly decreased muscular glycogen, mRNA levels of fatty acid transport protein 1, cationic amino acid transporter 1, and glucose transporter 4 in IUGR piglets compared with the other groups (p < 0.05). The results of the present study showed that IUGR impaired skeletal muscle growth and disturbed the hormone and mRNA expression of genes related to energy metabolism, which led to a more severe energy deficit when receiving postnatal nutritional restriction. Postnatal nutritional restriction resulted in delayed myofiber maturation of the piglets, which may be associated with the transformation of MyHC isoform and the change of metabolic status.

Macronutrient Supplements in Preterm and Small-for-Gestational-Age Animals: A Systematic Review and Meta-analysis

Early macronutrient supplementation in preterm and/or small-for-gestational-age (SGA) infants may improve growth but have detrimental effects on later cardio-metabolic health which may be sex-specific. We systematically reviewed the long-term effects of early macronutrient supplementation in preterm and SGA animals and whether these differ by sex. Using Cochrane Neonatal and SYRCLE methodologies we included random or quasi-random studies that allocated non-human mammals to macronutrient supplements or no supplements between birth and weaning and assessed post-weaning outcomes. We used random-effects models to calculate standardized mean differences (SMD) with 95% confidence intervals (CIs). Six studies provided low to very-low-quality evidence that macronutrient supplementation increased weight in juvenile rats (SMD; 95% CI: 2.13; 1.00, 3.25; 1 study, n = 24), increased leptin concentrations in older adults (1.31; 0.12, 2.51; 1 study, n = 14 male rats), but decreased leptin concentrations in young adults (-1.13; -2.21, -0.05; 1 study, n = 16 female rats) and improved spatial learning and memory (qualitative data; 1 study). There was no evidence of sex-specific effects and no overall effect on length, serum lipids, body composition, HOMA-IR, or blood pressure. Macronutrient supplements may affect later growth, metabolism, and neurodevelopment of preterm and SGA animals, but evidence is limited and low quality.

Potential risk factors related to pig body weight variability from birth to slaughter in commercial conditions

The aim of this observational study is to identify risk factors associated with body weight (BW) variability in three data sets (DS) in commercial conditions. A total of 1,009 (DS1), 460 (DS2), and 1304 (DS3) male and female crossbreed pigs (Pietrain × [Landrace × Large White]), respectively, were included in each trial. Pigs were periodically weighed until slaughter. Then, variables such as length of gestation, length of lactation, parity, litter size, sex, birth BW, and ADG were considered. Pigs remaining on the farm after two loads to the slaughterhouse were defined as last group of animals sent to slaughterhouse (LGS). Descriptive statistics of variability were calculated, and a risk analysis approach was used to look for the factors related to LGS. A multiple logistic regression was performed to identify all variables that were significant (P < 0.05). The risk ratio (RR), odds ratio (OR), and population attributable risk (PAR) were calculated for all of the significant variables after transforming all of them into binary factors using the 25th percentile as the cut-off point. Results showed that the major part of the variability (as CV) comes from birth (20% to 25%) and increased only a little during lactation and 14-d post weaning. From this point onwards, CV tended to decrease, as pigs got closer to the marketing weight (down 11.5% to 12.7%). Regarding the indicators selected, RR, OR, and PAR presented similar trends in the three DS studied. Therefore, for the variables finally included, these indicators had their minimum values at the start of the cycle and then gradually increased at the end. Those results, based on an epidemiological approach, suggest that the closer to the end of the cycle the greater the probability for a light piglet of being/becoming LGS. It might be explained by the shorter available time to efficiently implement preventive measures aimed to improve the performance of delayed pigs and, thus, reducing variability.Those results, based on an epidemiological approach, make sense as the probability for a light piglet to be a LGS increases the closer to the end of the cycle, due to the short time to implement preventive measures and increase the performance of delayed pigs and reduce variability. The differential PAR associated with both, the nursery and the growing period, was 1.7% and 1.5% for DS1, 5.1% and 3.1% for DS2, and 3.7% and 2.8% for DS3. For the lactation period, the results were 4.3% for DS2 and 4.5% for DS3. Results suggest that the most critical periods, in relation to retardation of growth in swine, are lactation and nursery. Implementing measures that maintain risk factors under or above thresholds, especially in the initial phases of growth, will reduce the percentage of LGS pigs and positively affect the overall homogeneity of the batch.

Estimation of direct and maternal genetic parameters for individual birth weight and probe weight using cross-fostering information

A total of 246 357 measurements of birth (BW) and probe (PW) weights of purebred Yorkshire and Landrace pigs were used to compare the fitting of two alternate models including either common-litter effect or cross-fostering group effect to account for common environmental variation. PW, is a live ultrasonic weight measurement taken when the pigs are 100 ± 30 kg, following national standards. The common-litter effect was defined as piglets born into the same litter, and the group effect was used to account for cross-fostering, and defined as the effect common to piglets raised by the same nurse-sow, regardless of whether that piglet was born into that litter or not. It was found that the cross-fostering group explained 5% more environmental variation in BW when compared with the common-litter effect, indication that BW is a criterion in cross-fostering. Cross-fostering also explained 1% more environmental variation in PW in both the Yorkshire and Landrace. When the cross-fostering group effect was included in place of the common-litter effect, the direct and maternal genetic heritability estimates were similar, but residual variances were reduced. This study advanced the understanding of the effects of cross-fostering on PW, its association with BW and its implications in modern pig breeding programs.

High nutrient intake during the early postnatal period accelerates skeletal muscle fiber growth and maturity in intrauterine growth-restricted pigs

Background

Intrauterine growth-restricted (IUGR) neonates impair postnatal skeletal muscle growth. The aim of this study was to investigate whether high nutrient intake (HNI) during the suckling period could improve muscle growth and metabolic status of IUGR pigs.

Methods

Twelve pairs of IUGR and normal birth weight (NBW) pigs (7 days old) were randomly assigned to adequate nutrient intake and HNI formula milk groups. Psoas major (PM) muscle sample was obtained after 21 days of rearing.

Results

IUGR decreased cross-sectional areas (CSA) and myofiber numbers, activity of lactate dehydrogenase (LDH), and mRNA expression of insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), mammalian target of rapamycin (mTOR), ribosomal protein s6 (RPS6), eukaryotic translation initiation factor 4E (eIF4E), protein expression of phosphorylated mTOR (P-mTOR), and phosphorylated protein kinase B (P-Akt) in the PM muscle of pigs. Irrespective of birth weight, HNI increased muscle weight and CSA, the concentration of RNA, and ratio of RNA to DNA, as well as ratio of LDH to β-hydroxy-acyl-CoA-dehydrogenase in the PM muscle of pigs. Furthermore, HNI increased percentages of MyHC IIb, mRNA expression of IGF-1, IGF-1R, Akt, mTOR, RPS6, and eIF4E, as well as protein expression of P-mTOR, P-Akt, P-RPS6, and P-eIF4E in the PM muscle of pigs.

Conclusion

The present findings suggest that high nutrient intake during the suckling period could improve skeletal muscle growth and maturity, which is associated with increasing the expression of protein deposition-related genes and accelerating the development of glycolytic-type myofiber in pigs.

Electronic supplementary material

The online version of this article (10.1186/s12263-018-0612-8) contains supplementary material, which is available to authorized users.

Nutritional support for low birth weight infants: insights from animal studies

Infants born with low birth weights (<2500 g, LBW), accounting for about 15 % of newborns, have a high risk for postnatal growth failure and developing the metabolic syndromes such as type 2 diabetes, CVD and obesity later in life. Improper nutrition provision during critical stages, such as undernutrition during the fetal period or overnutrition during the neonatal period, has been an important mediator of these metabolic diseases. Considering the specific physiological status of LBW infants, nutritional intervention and optimisation during early life merit further attention. In this review, the physiological and metabolic defects of LBW infants were summarised from a nutritional perspective. Available strategies for nutritional interventions and optimisation of LBW infants, including patterns of nutrition supply, macronutrient proportion, supplementation of amino acids and their derivatives, fatty acids, nucleotides, vitamins, minerals as well as hormone and microbiota manipulators, were reviewed with an aim to provide new insights into the advancements of formulas and human-milk fortifiers.

Breeding animals for quality products: not only genetics

The effect of the Developmental Origins of Health and Disease on the spread of non-communicable diseases is recognised by world agencies such as the United Nations and the World Health Organization. Early environmental effects on offspring phenotype also apply to domestic animals and their production traits. Herein, we show that maternal nutrition not only throughout pregnancy, but also in the periconception period can affect offspring phenotype through modifications of gametes, embryos and placental function. Because epigenetic mechanisms are key processes in mediating these effects, we propose that the study of epigenetic marks in gametes may provide additional information for domestic animal selection.

Developmental Origins of Health and Disease in swine: implications for animal production and biomedical research

The concept of Developmental Origins of Health and Disease (DOHaD) addresses, from a large set of epidemiological evidences in human beings and translational studies in animal models, both the importance of genetic predisposition and the determinant role of maternal nutrition during pregnancy on adult morphomics and homeostasis. Compelling evidences suggest that both overnutrition and undernutrition may modify the intrauterine environment of the conceptus and may alter the expression of its genome and therefore its phenotype during prenatal and postnatal life. In fact, the DOHaD concept is an extreme shift in the vision of the factors conditioning adult phenotype and supposes a drastic change from a gene-centric perspective, only modified by lifestyle and nutritional strategies during juvenile development and adulthood, to a more holistic approach in which environmental, parental, and prenatal conditions are strongly determining postnatal development and homeostasis. The implications of DOHaD are profound in all the mammalian species and the present review summarizes current knowledge on causes and consequences of DOHaD in pigs, both for meat production and as a well-recognized model for biomedicine research.

The increasingly complex regulation of adipocyte differentiation

Adipose (AD) tissue development and function relies on the ability of adipocytes to proliferate and differentiate into lipid-containing cells that also have endocrine function. Research suggests that certain conditions can induce AD tissue stem cells to differentiate into various cell types and that the microenvironment of the cell, including the extracellular matrix (ECM), is essential in maintaining cell and tissue function. This review provides an overview of factors involved in the proliferation and differentiation of adipocytes. A brief review of the numerous factors that influence PPARγ, the transcription factor thought to be the master regulator of adipocyte differentiation, provides context of established pathways that regulate adipogenesis. Thought provoking findings from research with hypoxia that is supported by earlier research that vascular development is related to adipogenesis are reviewed. Finally, our understanding of the critical role of the ECM and environment in adipogenesis is discussed and compared with studies that suggest that adipocytes may dedifferentiate and can convert into other cell types.

Postnatal nutritional restriction affects growth and immune function of piglets with intra-uterine growth restriction

Postnatal rapid growth by excess intake of nutrients has been associated with an increased susceptibility to diseases in neonates with intra-uterine growth restricted (IUGR). The aim of the present study was to determine whether postnatal nutritional restriction could improve intestinal development and immune function of neonates with IUGR using piglets as model. A total of twelve pairs of normal-birth weight (NBW) and IUGR piglets (7 d old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake (RNI) by artificially liquid feeding for a period of 21 d. Blood samples and intestinal tissues were collected at necropsy and were analysed for morphology, digestive enzyme activities, immune cells and expression of innate immunity-related genes. The results indicated that both IUGR and postnatal nutritional restriction delayed the growth rate during the sucking period. Irrespective of nutrient intake, piglets with IUGR had a significantly lower villous height and crypt depth in the ileum than the NBW piglets. Moreover, IUGR decreased alkaline phosphatase activity while enhanced lactase activity in the jejunum and mRNA expressions of Toll-like receptor 9 (TLR-9) and DNA methyltransferase 1 (DNMT1) in the ileum of piglets. Irrespective of body weight, RNI significantly decreased the number and/or percentage of peripheral leucocytes, lymphocytes and monocytes of piglets, whereas the percentage of neutrophils and the ratio of CD4+ to CD8+ were increased. Furthermore, RNI markedly enhanced the mRNA expression of TLR-9 and DNMT1, but decreased the expression of NOD2 and TRAF-6 in the ileum of piglets. In summary, postnatal nutritional restriction led to abnormal cellular and innate immune response, as well as delayed the growth and intestinal development of IUGR piglets.

Management strategies to improve the performance of low birth weight pigs to weaning and their long-term consequences

Performance of pigs from birth to slaughter is a result of a complex interaction of factors, with the early stages of a pig's life likely to affect lifetime performance. During the preweaning stage, piglets are reliant on the sow for nutrition, and sibling competition is likely to affect growth, in particular for low birth weight (LBiW) piglets. The objective of the experiment was to determine the effect of litter composition (littermate weight) and milk supplementation during lactation on the performance of LBiW pigs to weaning and the long-term consequences of treatment to slaughter. The experiment was a 2 × 2 factorial with littermate weight (normal or LBiW) and provision of supplementary milk from d 1 to 28 (yes or no) as factors. A total of 265 piglets were selected within 24 h of birth and cross-fostered to create 2 litter types (LOW = LBiW pigs [≤ 1.25 kg] only and MX = both LBiW and normal birth weight pigs [1.6 to 2.0 kg]); half of the litters within a type were supplemented with milk and the other half were not. The behavior of litters given milk was recorded to identify milk consumption patterns. Piglets were weaned at d 28 and kept in their litters until d 70 and then subsequently housed in mixed groups until slaughter. No difference was observed at any stage in the ADG of pigs given access to supplementary milk or not (P > 0.05) nor was there any significant interaction between milk provision and litter composition (P > 0.05). However, LOW litters drank significantly more supplementary milk than MX litters (P < 0.001). There was a significant effect of litter type on ADG from d 14 to 28, with LBiW pigs in LOW litters performing better than those in MX litters (0.252 versus 0.217 kg/d; P < 0.05). At weaning, LBiW piglets in LOW litters weighed over 500 g more than those in MX litters (P < 0.05). In MX litters there was a significant interaction between birth weight and supplementary milk on the CV of BW from d 14 to slaughter (P < 0.05). In conclusion, grouping LBiW piglets with similar sized littermates preweaning can improve preweaning performance by reducing competition from heavier littermates; however, this advantage does not persist after weaning. Although supplementary milk does not improve LBiW pig performance before or after weaning, it affects their drinking behavior and can reduce the variation in the BW of LBiW piglets in mixed litters to slaughter.

Birth weight alters the response to postnatal high-fat diet-induced changes in meat quality traits and skeletal muscle proteome of pigs

Low birth weight (LBW) exerts persistent effects on the growth and development of offspring. The present study was conducted to test the hypothesis that LBW alters the response of pigs to high-fat (HF) diet-induced changes in meat quality and skeletal muscle proteome. Normal-birth weight (NBW) and LBW piglets were fed a control diet or a HF diet from weaning to slaughter at 110 kg body weight. Most of the meat quality traits were influenced by LBW. Meat quality analysis revealed that LBW piglets had a greater ability to deposit intramuscular lipids than their heavier littermates when fed a HF diet. Increased shear force, lower pH45min and drip loss were observed in the skeletal muscle of LBW piglets compared with NBW piglets. Proteomic analysis revealed forty-six differentially expressed proteins in the skeletal muscle of LBW and NBW piglets fed the control diet or HF diet. These proteins play a central role in cell structure and motility, glucose and energy metabolism, lipid metabolism, and cellular apoptosis, as well as stress response. Of particular interest is the finding that LBW altered the response to HF diet-induced changes in the expression of proteins related to stress response (heat shock protein) and glucose and energy metabolism (pyruvate kinase, phosphoglycerate mutase, enolase and triosephosphate isomerase). Taken together, our findings revealed that the HF diet-induced changes in the expression of glucose and energy metabolism-related proteins varied between NBW and LBW piglets, which provides a possible mechanism to explain higher intramuscular fat store in LBW pigs when fed a HF diet.

Intrauterine growth retardation increases the susceptibility of pigs to high-fat diet-induced mitochondrial dysfunction in skeletal muscle

It has been recognized that there is a relationship between prenatal growth restriction and the development of metabolic-related diseases in later life, a process involved in mitochondrial dysfunction. In addition, intrauterine growth retardation (IUGR) increases the susceptibility of offspring to high-fat (HF) diet-induced metabolic syndrome. Recent findings suggested that HF feeding decreased mitochondrial oxidative capacity and impaired mitochondrial function in skeletal muscle. Therefore, we hypothesized that the long-term consequences of IUGR on mitochondrial biogenesis and function make the offspring more susceptible to HF diet-induced mitochondrial dysfunction. Normal birth weight (NBW), and IUGR pigs were allotted to control or HF diet in a completely randomized design, individually. After 4 weeks of feeding, growth performance and molecular pathways related to mitochondrial function were determined. The results showed that IUGR decreased growth performance and plasma insulin concentrations. In offspring fed a HF diet, IUGR was associated with enhanced plasma leptin levels, increased concentrations of triglyceride and malondialdehyde (MDA), and reduced glycogen and ATP contents in skeletal muscle. High fat diet-fed IUGR offspring exhibited decreased activities of lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G6PD). These alterations in metabolic traits of IUGR pigs were accompanied by impaired mitochondrial respiration function, reduced mitochondrial DNA (mtDNA) contents, and down-regulated mRNA expression levels of genes responsible for mitochondrial biogenesis and function. In conclusion, our results suggest that IUGR make the offspring more susceptible to HF diet-induced mitochondrial dysfunction.

The protein level of isoenergetic formulae does not modulate postprandial insulin secretion in piglets and has no consequences on later glucose tolerance

Early postnatal nutrition is involved in metabolic programming, an excess of protein being suspected to enhance early growth and the propensity to later develop insulin resistance and type 2 diabetes mellitus. The aim of the present study was to test the hypothesis that excessive protein intake during the suckling period would overstimulate the endocrine pancreas in the short term and alter durably its maturation, contributing to the later disruption of glucose homeostasis. Normal-birth-weight and low-birth-weight piglets were fed isoenergetic formulae providing an adequate-protein (AP, equivalent to sow milk) or a high-protein (HP, +48 %) supply between 7 and 28 d of age and were fed a standard diet until 70 d of age. During the formula-feeding period, the HP formula did not modify postprandial insulin secretion but transiently increased fasting insulin and the homeostasis model assessment-insulin resistance index (HOMA-IR, P < 0·05). Fasting insulin and HOMA-IR were restored to AP piglets' values 1 month after weaning. The structure of the endocrine pancreas was not affected by the protein content of the formula. The weight at birth had no major effect on the studied parameters. We concluded that a high-protein supply during the suckling period does not interfere with insulin secretion and endocrine pancreas maturation in the short term. It has no consequences either on glucose tolerance 1 month after weaning. The present study demonstrated that up-regulation of postprandial insulin secretion is not involved in higher growth observed in piglets fed a HP formula.