July 30, 2020

Interpretive Summary: Rumen-protected arginine in ewe lambs

Interpretive Summary: Rumen-protected arginine in ewe lambs: effects on circulating serum amino acids and carotid artery hemodynamics

By: Anne Wallace

Arginine (Arg) is an amino acid needed for metabolism, immunity and blood pressure homeostasis. In ruminants, supplementation of Arg during the periconceptual period may potentially impact pregnancy outcomes.

Researchers evaluated how rumen-protected l-Arg (RP-ARG) supplementation affected circulating serum amino acids and carotid artery hemodynamics in Rambouillet ewes in this Journal of Animal Science study. They hypothesized that both carotid artery hemodynamics and circulating amino acids would be affected by RP-ARG, in a dose-dependent manner. Because rumen microbes degrade most orally supplemented amino acids, delivery of amino acids either in a rumen-protected form or by injection into the ruminant is required. Both these methods of may add additional cost and time. Therefore, fully understanding the efficacy and health effects of amino acid supplementation in ruminants in a research setting, prior to supplementation on a more massive scale, is important.

Three groups of ewes were given RP-ARG in doses of 90, 180 and 360 mg while a fourth control group was provided with no supplemental RP-ARG. After two weeks, ewes fed RP-ARG had improved peripheral tissue blood perfusion, lower vascular resistance of blood flow and increased levels of the serum amino acids Ornithine and Aspartate, with 180 mg reported by the authors as the ideal dose of RP-ARG (better than 90 mg but same as 360 mg).

The results of this study support the authors’ hypothesis and suggest that supplementation with 180 mg of RP-ARG benefits ewes. Future studies evaluating the effects of RP-ARG on ewes or their offspring, when ewes are in the periconceptual period or during gestation, may be warranted.