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

Abstract

A great number of studies have investigated the potential of L-carnitine as feed additive to improve performance of different monogastric and ruminant livestock species, with, however, discrepant outcomes. In order to understand the reasons for these discrepant outcomes, it is important to consider the determinants of L-carnitine status and how L-carnitine status is regulated in the animal's body. While it is a long-known fact that L-carnitine is endogenously biosynthesized in certain tissues, it was only recently recognized that critical determinants of L-carnitine status, such as intestinal L-carnitine absorption, tissue L-carnitine uptake, endogenous L-carnitine synthesis and renal L-carnitine reabsorption, are regulated by specific nutrient sensing nuclear receptors. This review aims to give a more in-depth understanding of the basic mechanisms of the regulation of L-carnitine status in monogastrics taking into account the most recent evidence on nutrient sensing nuclear receptors and evaluates the efficacy of L-carnitine as feed additive in monogastric livestock by providing an up-to-date overview about studies with L-carnitine supplementation in pigs and poultry.

Comparisons of carcass traits, meat quality, and serum metabolome between Shaziling and Yorkshire pigs

“…From 60 d of age, the decreasing alteration of L∗ and b∗ values is opposite to the uptrend of L-carnitine content, which fits in with the negative correlations among L-carnitine and L∗ and b∗ values. Except for its best-known function of importing long-chain fatty acid into the mitochondrion, L-carnitine can also regulate the activity of the pyruvate dehydrogenase complex to promote energy production from glucose ( Ringseis et al., 2018 ). Combined with our results of higher serum L-carnitine content and IMF content in Shaziling pigs, we speculated that the carnitine distribution in the Shaziling pigs was different from that in the Yorkshire pigs, with more carnitine distributed in the serum and less in the muscle.…”

Effect of dietary supplementation with l-carnitine, chromium, and selenium on the performance of finishing pigs

“…The inconsistent results for the use of L-carnitine can be attributed to several causes, such as the sanitary status; the age of the animals; and environmental, genetic, and nutritional factors (JAMES et al, 2013;RINCKER et al, 2003). In the present study, the dose of 50 mg L-carnitine kg -1 of feed was within the values commonly employed in experiments and commercial farming (HARMEYER, 2003;OWEN et al, 2001;RINGSEIS et al, 2018) and proved effective under the conditions of this test. The effect of L-carnitine might be explained by Rincker et al (2003), who stated that L-carnitine acts in nutrient partition, which modifies the body composition and translates into increased weight gain and improved feed conversion.…”

“…Therefore, L-carnitine supplementation decreases body fat levels and increases protein deposition (HEO et al, 2000;PIETRUSZKA et al, 2009), a scenario effectively linked to improved FC as found in this research. Ringseis et al (2018) demonstrated positive results regarding performance and meat quality by supplementing growing and finishing pigs with doses between 49 and 64 mg kg -1 . Nonetheless, there are contrasting observations.…”

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 supports the hypothesis that CAR promotes embryo viability and this beneficial effect is mediated through an improvement in in utero nutrition (14) . The mechanisms in which CAR supplementation improves in utero nutrition in sows have been reviewed in detail by Ringseis et al (42) , concluding that an increase in sow CAR status improves lipid and carbohydrate metabolism, which in turn improves energy generation in the tissues of sows.…”