EFFECT OF L-CARNITINE ADMINISTRATION ON GROWTH PERFORMANCE, RUMEN AND BLOOD PARAMETERS AND CARCASS TRAITS OF GROWING Rahmani LAMBS

Evaluation of unprotected and rumen-protected L-carnitine in vitro and in vivo

This study aimed to evaluate the effectiveness of unprotected and rumen-protected L-carnitine through in vitro tests, rumen degradation tests, and in vivo tests. Twelve rumen-fistulated crossbred rams with similar body weights of 55 ± 3.6 kg and ages of 3 ± 0.2 yr old were divided into three treatment groups in a 3 × 3 Latin square design, G1 (basal diet with no additives), G2 (unprotected L-carnitine), or G3 (rumen-protected L-carnitine). Ruminal fluid and blood samples were collected before morning feeding on the last day of each experimental period (21 d). The percentage of L-carnitine remaining in the simulated rumen and abomasum and rumen increased with the increase in the wall material ratio (P < 0.05). L-carnitine supplementation decreased the plasma urea nitrogen concentration in the sheep (P < 0.05). G3 resulted in higher glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities as well as higher total antioxidant capacity (T-AOC) and lower malondialdehyde (MDA) concentrations in plasma than G1, and the difference was significant among the groups (P < 0.01). Thus, L-carnitine in the rumen could be protected by encapsulation for a certain time. Unprotected and rumen-protected L-carnitine supplementation effectively enhanced the antioxidant capacity of sheep, and the antioxidant capacity of sheep supplemented with rumen-protected L-carnitine was higher than that of sheep supplemented with unprotected L-carnitine.

Regulation of carnitine status in ruminants and efficacy of carnitine supplementation on performance and health aspects of ruminant livestock: a review

Carnitine has long been known to play a critical role for energy metabolism. Due to this, a large number of studies have been carried out to investigate the potential of supplemental carnitine in improving performance of livestock animals including ruminants, with however largely inconsistent results. An important issue that has to be considered when using carnitine as a feed additive is that the efficacy of supplemental carnitine is probably dependent on the animal's carnitine status, which is affected by endogenous carnitine synthesis, carnitine uptake from the gastrointestinal tract and carnitine excretion. The present review aims to summarise the current knowledge of the regulation of carnitine status and carnitine homeostasis in ruminants, and comprehensively evaluate the efficacy of carnitine supplementation on performance and/or health in ruminant livestock by comparing the outcomes of studies with carnitine supplementation in dairy cattle, growing and finishing cattle and sheep. While most of the studies show that supplemental carnitine, even in ruminally unprotected form, is bioavailable in ruminants, its effect on either milk or growth performance is largely disappointing. However, supplemental carnitine appears to be a useful strategy to offer protection against ammonia toxicity caused by consumption of high levels of non-protein N or forages with high levels of soluble N both, in cattle and sheep.