Adapted nutrition can improve the growth of low birth weight (LBW) piglets. Since maternal milk is thought to provide insufficient glutamine (Gln) for LBW piglets, the current study investigated the influence of Gln supplementation during the early suckling period on development and lipid deposition in skeletal muscle. The weight differences between LBW and normal birth weight (NBW) littermates persisted from birth to slaughter (p < 0.001). However, intramuscular Gln and Ala concentrations were altered in piglets according to the supplementation (p < 0.01). There were larger muscle fibers (p = 0.048) in Gln-supplemented piglets. Capillarization or nuclei number per muscle fiber was not influenced by birth weight (BiW) or Gln supplementation. Abundance of myosin heavy chain (MYH) isoforms was slightly altered by Gln supplementation. LBW piglets had more lipid droplets than NBW piglets at day 5 of life in both muscles (p < 0.01). The differences decreased with age. Adipocyte development increased with age, but was not influenced by BiW or supplementation. The results indicate that BiW differences were accompanied by differences in lipid deposition and muscle fiber structure, suggesting a delayed development in LBW piglets. Supplementation with Gln may support piglets to overcome those disadvantages.

Low birthweight (LBW) neonates show impaired growth compared with normal birthweight (NBW) neonates. Glutamine supplementation benefits growth of weaning piglets, while the effect on newborn piglets is not sufficiently clear. We examined the effect of early neonatal glutamine supplementation on piglet growth, milk intake, and metabolic parameters. Sow-reared pairs of newborn LBW (0.8-1.2 kg) and NBW (1.4-1.8 kg) male piglets received glutamine (1 g · kg-1 body mass (BM) · day (d)-1; Gln-LBW, Gln-NBW; n=24/group) or isonitrogenous alanine (1.22 g · kg-1 BM · d-1; Ala-LBW; Ala-NBW, n=24/group) supplementation at 1-5 or 1-12 d of age (daily in 3 equal portions at 07:00, 12:00, 17:00 by syringe feeding). We measured piglet BM, milk intake (1, 11-12 d), plasma metabolite, insulin, amino acid (AA) and liver triglyceride concentrations (5, 12 d). The Gln-LBW group had higher BM (+7.5%, 10 d, P=0.066, 11-12 d, P<0.05) and milk intake (+14.7%, P=0.015) than Ala-LBW group. At 5 d, Ala-LBW group had higher plasma triglycerides (+34.7%, P < 0.1) and lower carnosine (-22.5%, P<0.05) than Ala-NBW and Gln-LBW, and higher liver triglycerides (+66.9%, P=0.029) than Ala-NBW. At 12 d, plasma urea was higher (+37.5%, P<0.05) with Gln than Ala supplementation. Several proteinogenic AA in plasma were lower (P<0.05) in Ala-NBW vs. Gln-NBW group. Plasma arginine was higher (P<0.05) in Gln-NBW vs. Ala-NBW piglets (5, 12 d). Supplemental glutamine moderately improved growth and milk intake and affected lipid metabolism in LBW piglets and AA metabolism in NBW piglets, suggesting potential effects on intestinal and liver function.

Background It has been shown that small intestine development in low birth weight (LBW) piglets is impaired. Glutamine (Gln) has been reported to improve piglet health and intestinal function in weaned piglets, but data is scarce in suckling piglets. This study was conducted to investigate the effects of oral Gln supplementation compared to Alanine (Ala) on jejunal development and function in 5 and 12 d old male LBW and normal birth weight (NBW) suckling piglets. Results Gln had no effect on the jejunal morphology, development, tissue and digesta amino acid profiles and mRNA abundance of genes involved in amino acid transport, metabolism, glutathione synthesis in LBW piglets when compared to Ala supplementation and birth weight controls at 5 and 12 d. Only the concentration of Gln in jejunal tissue was higher in NBW piglets supplemented with Gln compared to Ala at 5 d (P < 0.05). A comparison of the birth weight groups showed no differences between LBW and NBW piglets at 5 and 12 d in any parameter. Jejunal crypt depth, villus height / width, tunica muscularis thickness, number of goblet and IgA positive cells, the ratio of jejunal RNA to DNA and the concentration of DNA, protein and RNA changed (P < 0.05) from 5 compared to 12 d. The concentrations of several free, and protein bound amino acids as well as amino metabolites differed between age groups in jejunal tissue but the digesta concentrations were affected to a lesser extent. Conclusions Oral Gln supplementation to suckling male piglets over the first 12 d of life was not associated with changes in jejunal parameters measured in this study. The absence of effects may indicate that Gln is absorbed as well as metabolized in the upper intestinal tract and thus could benefit intestinal development at a more proximal location.

Piglets with low birth weight (LBW) usually have reduced muscle mass and increased lipid deposition compared with their normal-birth-weight (NBW) littermates. Supplementation of piglets with amino acids during the first days of life may improve muscle growth and simultaneously alter the intramuscular lipid deposition. The aim of the current study was to investigate the influence of glutamine (Gln) supplementation during the early suckling period on lipid deposition in the longissimus muscle (MLD) and the role of different perilipin (PLIN) family members in this process. Four groups were generated consisting of 72 male LBW piglets and 72 NBW littermates. Piglets were supplemented with either 1 g Gln/kg body weight or an isonitrogenous amount of alanine (Ala) between days post natum (dpn) 1 and 12. Twelve piglets per group were slaughtered at 5, 12, and 26 dpn, and muscle tissue was collected. Perilipins were localized by immunohistochemistry in muscle sections. The mRNA and protein abundances of PLIN family members and related lipases were quantified by quantitative RT-PCR (qPCR) and western blots, respectively. While PLIN1 was localized around lipid droplets in mature and developing adipocytes, PLIN2 was localized at intramyocellular lipid droplets, PLIN3 and 4 at cell membranes of muscle fibers and adipocytes, and PLIN5 in the cytoplasm of undefined cells. The western blot results indicated higher protein abundances of PLIN2, 3, 4, and 5 in LBW piglets (p &lt; 0.05) at 5 dpn compared with their NBW littermates independent of supplementation, while not directly reflecting the mRNA expression levels. The mRNA abundance of PLIN2 was lower while PLIN4 was higher in piglets at 26 dpn in comparison with piglets at 5 dpn (p &lt; 0.01). Relative mRNA expression of LPL and CGI-58 was lowest in piglets at 5 dpn (p &lt; 0.001). However, ATGL mRNA was not influenced by birth weight or supplementation, but the Spearman correlation coefficient analysis revealed close correlations with PLIN2, 4, and 5 mRNA at 5 and 26 dpn (r &gt; 0.5, p &lt; 0.001). The results indicated the importance of birth weight and age for intramuscular lipid deposition and different roles of PLIN family members in this process, but no clear modulating effect of Gln supplementation.

Muscle growth of low birth weight (LBW) piglets may be improved with adapted nutrition. This study elucidated effects of glutamine (Gln) supplementation on the cellular muscle development of LBW and normal birth weight (NBW) piglets. Male piglets (n = 144) were either supplemented with 1 g Gln/kg body weight or an isonitrogeneous amount of alanine (Ala) between postnatal day 1 and 12 (dpn). Twelve piglets per group were slaughtered at 5, 12 and 26 dpn, one hour after injection with Bromodeoxyuridine (BrdU, 12 mg/kg). Muscle samples were collected and myogenic cells were isolated and cultivated. Expression of muscle growth related genes was quantified with qPCR. Proliferating, BrdU-positive cells in muscle sections were detected with immunohistochemistry indicating different cell types and decreasing proliferation with age. More proliferation was observed in muscle tissue of LBW-GLN than LBW-ALA piglets at 5 dpn, but there was no clear effect of supplementation on related gene expression. Cell culture experiments indicated that Gln could promote cell proliferation in a dose dependent manner, but expression of myogenesis regulatory genes was not altered. Overall, Gln supplementation stimulated cell proliferation in muscle tissue and in vitro in myogenic cell culture, whereas muscle growth regulatory genes were barely altered.