Dietary Administration of L-Carnitine During the Fattening Period of Early Feed Restricted Lambs Modifies Ruminal Fermentation but Does Not Improve Feed Efficiency

Abstract

Early feed restriction of lambs may program animals to achieve reduced feed efficiency traits as a consequence of permanent mitochondrial dysfunction. The hypothesis at the background of the present study is that dietary administration of L-Carnitine (a compound that promotes the activation and transportation of fatty acids into the mitochondria) during the fattening period of early feed restricted lambs can: (a) improve the biochemical profile of early feed restricted lambs, (b) improve feed efficiency, (c) modulate the ruminal and intestinal microbiota, and (d) induce changes in the gastrointestinal mucosa, including the immune status. Twenty-two newborn male Merino lambs were raised under natural conditions but separated from the dams for 9 h daily to allow feed restriction during the suckling period. At weaning, lambs were assigned to a control group being fed ad libitum a complete pelleted diet during the fattening phase (CTRL, n = 11), whereas the second group (CARN, n = 11) received the same diet supplemented with 3 g of L-Carnitine/kg diet. The results revealed that even though L-Carnitine was absorbed, feed efficiency was not modified by dietary L-Carnitine during the fattening period (residual feed intake, p > 0.05), whereas ruminal fermentation was improved [total short-chain fatty acids (SCFAs), 113 vs. 154 mmol/l; p = 0.036]. Moreover, a trend toward increased concentration of butyrate in the ileal content (0.568 vs. 1.194 mmol/100 ml SCFA; p = 0.074) was observed. Other effects, such as reduced heart weight, lower levels of markers related to muscle metabolism or damage, improved renal function, and increased ureagenesis, were detected in the CARN group. Limited changes in the microbiota were also detected. These findings suggest that L-Carnitine may improve ruminal fermentation parameters and maintain both the balance of gut microbiota and the health of the animals. However, the improved ruminal fermentation and the consequent greater accumulation of intramuscular fat might have hidden the effects caused by the ability of dietary L-Carnitine to increase fatty acid oxidation at the mitochondrial level. This would explain the lack of effects of L-Carnitine supplementation on feed efficiency and points toward the need of testing lower doses, probably in the context of animals being fed in excess non-protein nitrogen.

Rumen‐protected l‐carnitine supplementation during mating period altered metabolic status and reproductive performance of ewes

“…Dietary LC inclusion did influence the feed intake of the animals during the course of this experiment. The outcome of this work are in contrary with previous investigation indicating no clear impact of LC on DMI in fattening lambs (Martín et al, 2022). A recent study in Ghezel lambs indicated that dietary inclusion of LC up to 1.5 g/day did not alter the feed intake of the animals (Solhjoo et al, 2014).…”

Gut microbiota and meat quality

“…The abundance of Oscillibacter increased, while Phocaeicola and Christensenellaceae_R-7_group significantly decreased with the HR diet ( Wang K. et al, 2021 ). Dietary administration of L -carnitine can improve feed efficiency and modulate the ruminal and intestinal microbiota of lambs, ruminal fermentation was also improved with higher concentration of SCFA were detected ( Martin et al, 2022 ).…”

Physicochemical Characteristics, Selected Lipid Content and Protein Bioactive Compounds of Lamb Meat Depending on Aging Time and Muscle Type

“…Many studies have shown that breed, age at slaughter, the feeding system and related muscle development and the proportion of different types of muscle fibers determine important meat characteristics for the consumer, such as color, tenderness, juiciness or intramuscular fat content, as well as the presence of biologically active ingredients [3][4][5][6][7][8][9][10][11]. The quality of the meat is also affected by physiological, biochemical and metabolic changes that occur during meat aging.…”