Dietary l-carnitine Supplementation Modifies the Lipopolysaccharide-Induced Acute Phase Reaction in Dairy Cows

SIMPLE SUMMARY: l-carnitine might limit the mitochondrial energy generation from fatty acids, particularly in periods of enhanced energy requirement such as during lipopolysaccharide (LPS) mediated innate immune responses. This study examined the influence of a dietary l-carnitine supplementation on dairy cows in mid-lactation which were challenged by an injection with LPS. Results suggest that this intervention supported the energy metabolism of the cows during LPS-induced acute phase reaction (APR). ABSTRACT: l-carnitine plays an important role in energy metabolism through supporting the transport of activated fatty acids to the subcellular site of β-oxidation. An acute phase reaction (APR) is known as an energy consuming process. Lipopolysaccharides (LPS) are often used in animal models to study intervention measures during innate immune responses such as APR. Thus, the aim of the study was to investigate the effects of dietary l-carnitine supplementation during an LPS-induced APR in mid-lactating German Holstein cows. Animals were assigned to a control (CON, n = 26) or l-carnitine group (CAR, n = 27, 25 g rumen-protected l-carnitine/cow/d) and received an intravenous injection of LPS (0.5 μg/kg body weight) at day 111 post-partum. Blood samples were collected from day 1 pre-injection until day 14 post-injection (pi). From 0.5 h pi until 72 h pi blood samplings and clinical examinations were performed in short intervals. Clinical signs of the APR were not altered in group CAR except rumen motility which increased at a lower level compared to the CON group after a period of atonia. Group CAR maintained a higher insulin level compared to group CON even up to 72 h pi which might support glucose utilization following an APR.