During early pregnancy when placental growth is fastest, the level of arginine and its precursor ornithine is elevated in porcine amniotic and allantoic fluid (Wu et ah, 2006). This abundance is associated with a high syntheses rate of nitric oxide and polyamine in the porcine placentae (Self et al., 2004). Wu et al. (2004) provided evidence showing that both nitric oxide and polyamines play key roles in angiogenesis, which is a critical event during placental growth and fetal development (Town et al., 2005). These observations led to the hypothesis that arginine is important for placental and fetal development. Recently, Berard and Bee (2010) showed that supplementing the gestation diet with 1-arginine, positively affected primary myofiber hyperplasia in semitendinosus muscles (STM) of 75 d old fetuses. Because primary fibers serve as a scaffold for the formation of secondary fibers we hypothesized that offspring from sows fed extra arginine bare the potential for greater fiber hyperplasia and ultimately more efficient postnatal growth. Especially low-birth weight pigs display low myofiber numbers. Thus, the goal of this experiment was to evaluate if arginine supplementation of the dams has a positive effect on muscle development of such piglets.
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