Effects of Oral Glutamine Supplementation on Early Postnatal Muscle Morphology in Low and Normal Birth Weight Piglets

Abstract

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.

Distinct Roles of Perilipins in the Intramuscular Deposition of Lipids in Glutamine-Supplemented, Low-, and Normal-Birth-Weight Piglets

“…Results of total lipid droplet area in muscle fibers and in adipocytes were reported in our former publication (5). We observed more lipid droplets in LBW piglets than in their NBW littermates at 5 dpn.…”

“…Our previous study indicated a clear difference between LBW and NBW piglets in the abundance of lipid droplets within muscle fibers at 5 dpn ( 5 ). The area percentage of intramyocellular lipid droplets decreased during the first days of life by more than 80%.…”

“…The study involved German Landrace male piglets with 72 LBW and 72 NBW littermates, nursed and supplemented with Gln or an isonitrogenous amount of alanine (Ala) as described in detail in our former publication ( 5 ). Twelve piglets per group were sacrificed at 5, 12, or 26 dpn.…”

“…In the current project, we attempted to ameliorate the disadvantages of the LBW piglets with adapted nutrition, in particular with glutamine (Gln) supplementation, which was assumed insufficient in maternal milk especially for LBW piglets (3,4). In our previous investigation (5), we observed fewer muscle fibers and more intramyocellular lipid droplets at 5 days post natum (dpn) in LBW piglets. Moreover, Gln supplementation was shown to increase intramuscular availability of free Gln in skeletal muscle in a short term and to influence muscle fiber size, but had no influence on further muscle morphology traits and a minor influence on the abundance of myosin heavy chain isoforms.…”

“…Intramuscular fat in pig represents only a small part of total body fat ( 6 ). The lipids within skeletal muscle are either stored in intramuscular adipocytes or within muscle fibers as intramyocellular lipid droplets ( 5 ). These intramuscular lipid droplets, also named lipid or fat bodies, play a vital role in lipid homeostasis in skeletal muscle ( 11 ).…”