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This Article Full Text (PDF) All Versions of this Article: jas.2008-1662v1 87/7/2216    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Lösel, D. Articles by Rehfeldt, C. Search for Related Content PubMed PubMed Citation Articles by Lösel, D. Articles by Rehfeldt, C.

L-carnitine supplementation during suckling intensifies the early postnatal skeletal myofiber formation in piglets of low birth weight

Research Unit Muscle Biology and Growth, Research Institute for the Biology of Farm Animals, D-18196 Dummerstorf, Germany

rehfeldt{at}fbn-dummerstorf.de

Abstract

Piglets of low birth weight exhibit a lower total number of skeletal myofibers at birth and throughout life compared with piglets of middle and heavy birth weight, which is associated with impaired (lean) growth and quality of carcass and meat at market weight. We investigated the effect of L-carnitine supplementation to suckling piglets of different birth weights on early postnatal myofiber formation, muscle growth, and body composition. A total of 48 piglets of low (LW) and middle (MDW) birth weight from nine German Landrace gilts received either 400 mg of L-carnitine (carnitine, n = 25) or a placebo (control, n = 23) once daily from d 7 to 27 of age and were slaughtered on d 28 of age (weaning). Carnitine-supplemented piglets deposited less fat as indicated by a lower proportion of perirenal (P = 0.1) and intramuscular fat (P = 0.05). Circulating glucose concentrations tended to be greater in supplemented LW piglets (P = 0.13). The concentration of carnitine in semitendinosus (ST) muscle was approximately doubled (P < 0.001) by supplementation, with emphasis on the proportion of esterified carnitine. The ratio of lactate dehydrogenase to isocitrate dehydrogenase tended (P = 0.12) to be smaller in ST muscle of supplemented piglets indicating a more oxidative muscle metabolism. The total number of ST myofibers was increased by 13% (P = 0.02) in supplemented LW piglets thereby reaching the unchanged level of MDW littermates. In addition, supplemented LW piglets displayed a 2.4-fold mRNA expression of the gene encoding the embryonic isoform of the myosin heavy chain in ST muscle than control piglets (P = 0.05), but there were no differences in the proportion of fibers positively staining for the embryonic myosin isoform. L-carnitine-supplemented piglets exhibited a higher DNA:protein ratio (P = 0.02) in ST muscle, which resulted from a higher DNA concentration (P = 0.04). However, the ST muscle of L-carnitine-supplemented piglets was not less mature as indicated by unchanged myofiber size, creatine kinase activity, and protein concentration. The results indicate that energy balance has been improved through intensified fatty acid oxidation. As a consequence, myogenic proliferation appears to be stimulated, which in LW piglets may have contributed to a compensatory increase in myofiber number. Thus, piglets, particularly those of low birth weight, could profit from an early postnatal L-carnitine supplementation, which may attenuate the negative consequences of low birth weight on body composition and meat quality at market weight.

Key Words: carnitine • fiber number • growth • myogenesis • pig • skeletal muscle