Influence of l‐carnitine and l‐arginine on protein synthesis and maturation of the semitendinosus muscle of lightweight piglets

Abstract

SummaryLightweight (LW) piglets from large litters display impaired growth performance compared with heavier littermates. This study investigated the growth performance and muscle development of early-weaned LW piglets (birthweight <1.2 kg) from large litters (17.3 ± 3.0 total born per litter), fed ad libitum a milk replacer supplemented with either l-carnitine (CAR) or l-arginine (ARG) from day 7 to day 28 of age. In total, 36 female and entire male Swiss Large White piglets, weaned on day 7 of age, were artificially reared in pairs in rescue decks. They were allocated to one of three dietary treatments: unsupplemented control (CON), 0.48 g l-carnitine·piglet ·day −1 (ARG). Milk replacer was prepared daily in a 1:4 powder-to-water ratio and fed ad libitum. Piglets were weighed at birth and on days 7, 14, 21 and 28.Feed intake was assessed daily. Piglets were euthanized on day 28. The entire semitendinosus muscle (STM) was collected, and organs were weighed. Subsequently, the STM was divided into the light (STM l ) and dark (STM d ) portion, and contractile and metabolic traits were analysed by ATP histochemistry, enzyme activities and gene expression. No differences in growth performance, organ and STM weight and on contractile traits were found between groups. A tendency (p < .10) for an elevated lipid oxidation enzyme activity in the STM l and STM d and greater (p < .05) phosphorylation of the mammalian target of rapamycin pathway in the STM l of CAR compared with CON piglets was found.Despite these metabolic responses, the lack of effect of CAR and ARG supplementation on growth performance suggests that providing the milk replacer ad libitum in combination with added CAR and ARG is insufficient for eliciting faster growth of LW piglets. K E Y W O R D Samino acid, artificial rearing, growth performance, litter size, milk replacer | INTRODUCTIONIncreased litter size, a large within-litter variation and decrease in the average birthweight (BtW) of the litter are all consequences of selection for hyperprolific sows in the commercial pig production (Rutherford et al., 2013). Simultaneously in such sows, milk yield and number of functioning teats does no longer correspond to the number of piglets in the litter (Andersen, Naevdal, & Boe, 2011). This compromises the growth of the piglets in a way that they are unable to reach their full potential (Harrell, Thomas, & Boyd, 1993). Furthermore, lightweight compared with the litter average (Quiniou, Dagorn, & Gaudré, 2002), where the main cause of death across all BtW categories is documented to be crushing by the sow (Edwards, 2002). However, it is argued that due to undernourishment, LW piglets reside for longer periods in close proximity of the sow, thereby increasing the risk of crushing (Weary, Pajor, Thompson, & Fraser, 1996). In this context, early artificial rearing by relocating excess piglets to rescue decks and feeding them on milk replacer will naturally remove their risk of being crushed by the sow. Applying milk replacer to early-weaned piglets has been sh...

Basic mechanisms of the regulation of L‐carnitine status in monogastrics and efficacy of L‐carnitine as a feed additive in pigs and poultry

“…In another study of the same group with an identical experimental design but a slightly lower L‐carnitine dose (400 mg/piglet and day), L‐carnitine supplementation also failed to significantly improve growth performance, semitendinosus muscle weight and myofibre size of low birth‐weight piglets ( n = 30, female and castrated from Swiss Large White sows) reared with a mainly cow milk product‐based milk replacer from day 7 to 28 of age (Madsen, Mueller et al., ). It is likely that the same reason as in the study before (Madsen, Seoni et al., ) accounts for the lack of effect of supplemental L‐carnitine.…”

“…Nevertheless, the results of this study indicated that the beneficial effect of early‐postnatal L‐carnitine supplementation in low birth‐weight piglets on myofibre number at weaning disappears during the post‐weaning/growing and finishing period. Also, no effect of L‐carnitine supplementation on BW gains and gain‐to‐feed ratio was observed in a very recent study with light‐weight piglets (birth weight <1.2 kg, n = 36, female and entire male from Swiss Large White sows), which were early weaned on day 7 of age and artificially reared with a milk replacer based on cow milk products and offered either 0 (control) or 480 mg L‐carnitine per day until day 28 of age (Madsen, Seoni, Kreuzer, Silacci, & Bee, ). In addition, this study did not find any effects of supplemental L‐carnitine on skeletal muscle weights and contractile and metabolic traits of skeletal muscle of early‐weaned pigs (Madsen, Seoni et al., ).…”

“…Also, no effect of L‐carnitine supplementation on BW gains and gain‐to‐feed ratio was observed in a very recent study with light‐weight piglets (birth weight <1.2 kg, n = 36, female and entire male from Swiss Large White sows), which were early weaned on day 7 of age and artificially reared with a milk replacer based on cow milk products and offered either 0 (control) or 480 mg L‐carnitine per day until day 28 of age (Madsen, Seoni, Kreuzer, Silacci, & Bee, ). In addition, this study did not find any effects of supplemental L‐carnitine on skeletal muscle weights and contractile and metabolic traits of skeletal muscle of early‐weaned pigs (Madsen, Seoni et al., ). However, it has to be considered that the basal L‐carnitine content of the milk replacer used was probably relatively high, because it consisted mainly (97.4%) of cow milk products (whey powder, whole milk powder, milk protein), which have a high L‐carnitine content (the L‐carnitine content of whole milk, butter milk, whey and skimmed milk ranges between 330 and 400 mg/kg DM (Knüttel‐Gustavsen & Harmeyer, ).…”

Effect of dietary l-carnitine supplementation to sows during gestation and/or lactation on sow productivity, muscle maturation and lifetime growth in progeny from large litters

“…This is evidenced by the up-regulated expression of selected genes in the STM l of these piglets at birth. An increased expression of MyHC IIb and of MyHC IIx indicates increased muscle maturation, owing to a shift towards a more glycolytic and less oxidative metabolism in the muscle (46) . Primary fibres start to express slow MyHC and mature into type I slow muscle fibres, whereas secondary fibres express fast MyHC and mature into type IIx or IIb fibres (47) .…”

Glutamine supplementation stimulates cell proliferation in skeletal muscle and cultivated myogenic cells of low birth weight piglets

“…The delayed growth of LBW piglets is mainly due to a slower development of skeletal muscle as the myogenic activity is usually impaired in these animals during the fetal and early postnatal period 3 , 4 . These disadvantages could cause long-term negative effects in LBW piglets 1 and different adapted feeding strategies have been developed to compensate the growth delay and improve the body composition of LBW piglets 5 – 7 . Feeding with amino acids can stimulate protein synthesis in all tissues, especially in skeletal muscle as reviewed by Davis et al 3 .…”