title: Early postnatal food intake alters myofiber maturation in pig skeletal muscle.
abstract: We examined the effects of undernutrition on muscle development during the first postnatal week in pigs. Eighteen piglets were subjected to three nutritional levels (300, 200 or 100 g/(kg body. d) of colostrum then milk) between birth and slaughter at 7 d of age. Longissimus lumborum (LL), a fast-twitch glycolytic muscle, and rhomboideus (RH), a mixed slow- and fast-twitch oxido-glycolytic muscle, were taken for myofiber typing and biochemical analyses. Enzyme activities of lactate dehydrogenase (LDH), citrate synthase (CS) and beta-hydroxy-acyl-CoA-dehydrogenase (HAD) were used as markers of glycolytic, oxidative and lipid beta-oxidation capacities, respectively. Undernutrition selectively decreased (P < 0.001) hypertrophy of the future fast-twitch glycolytic fibers in LL. Contractile and metabolic maturation was delayed in the later maturing LL, as reflected by a decrease in muscle protein concentration (P < 0.01), an increase (P < 0.05) in the percentage of myofibers still expressing the fetal myosin heavy chain (MyHC), a lower postnatal increase in LDH activity (P < 0.001) and a delayed decrease in the percentage of IIa MyHC positive fibers (P < 0.001). Otherwise, restriction tended (P < 0.10) to increase the percentage of slow type I MyHC containing fibers in both muscles and of alpha-cardiac MyHC positive fibers in RH (P < 0.05). The LDH/CS ratio decreased dramatically (P < 0.001) after restriction, to a greater extent in LL than in RH. These changes denoted a more oxidative metabolism using fewer carbohydrates and more lipids in restricted pigs, as suggested by the increased activity of HAD (P < 0.001) and decreased respiratory quotient (P < 0.001).
authors.affiliation: Institut National de la Recherche Agronomique (INRA), Unité Mixte de Recherche sur le Veau et le Porc (UMRVP), 35590 Saint-Gilles, France. louis.lefaucheur@rennes.inra.fr
authors.forename: Louis
authors.initials: L
authors.lastname: Lefaucheur
authors.forename: Patrick
authors.initials: P
authors.lastname: Ecolan
authors.forename: Yves-Marie
authors.initials: YM
authors.lastname: Barzic
authors.forename: Julia
authors.initials: J
authors.lastname: Marion
authors.forename: Jean
authors.initials: J
authors.lastname: Le Dividich
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005508:Food Deprivation / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000254:growth & development*; D013552:Swine
chemical_list: D015094:3-Hydroxyacyl CoA Dehydrogenases; D007770:L-Lactate Dehydrogenase; D002950:Citrate (si)-Synthase