Leucine

L-Leucine · Leu · BCAA

Mechanism

Leucine is an essential, branched-chain amino acid (BCAA) and acts beyond its pure building-block function as a signalling molecule: it activates the mTORC1 signalling pathway and thereby stimulates the initiation of muscle protein synthesis. In horses it has been shown that feed or amino-acid intake switches on mTOR-dependent signalling pathways in skeletal muscle; the specific, isolated role of leucine is, however, less extensively studied in the horse than in rodents and humans, from whose data much is transferred. Leucine is discussed in the field of muscle maintenance and recovery, particularly in the growing, in-training or older horse. NRC 2007 and GfE 2014 primarily quantify lysine as the balanced, first-limiting amino acid (in part additionally threonine/methionine); a specific leucine requirement is not defined, which is why dosages are derived from analogy and individual studies.

Cautions

· Mind the amino-acid balance - isolated BCAA supplementation can trigger an antagonism with isoleucine/valine.
· No substitute for sufficiently high-quality total protein and a covered lysine requirement.
· Evidence for isolated performance/muscle effects in the horse is limited; much is extrapolated from rodent/human data.

Sources

NRC 2007NRC - Nutrient Requirements of Horses (2007): Lysin als bilanzierte erstlimitierende AS, kein eigener Leucin-Bedarf

Urschel et al.Urschel KL et al. - mTOR-Signalweg und Muskelproteinsynthese beim Pferd (equine Fütterungsstudien)

GfE 2014GfE - Empfehlungen zur Energie- und Nährstoffversorgung von Pferden (2014): Protein/Lysin, kein separater Leucin-Bedarf

Equiterna Score

76/100

high overall

Science7.7/10

Practical experience8/10

Safety7.2/10

Overall score scale

high overall75–100solid55–74limited0–54

How the Equiterna Score is built

The Equiterna Score combines three dimensions into a value of 0-100: science (40%), practical experience (30%) and safety (30%). It is transparently derived from evidence level, attributed sources (PubMed/journals), legal classification and cautions. The FEI doping status is shown separately as a competition-law note and does not enter the score. Commissions and vendor relationships have no influence on the score. In addition, the editorial safety rating caps the result: it limits the safety dimension and the overall tier (orange: at most solid). For entries rated red, no score is calculated at all. The rating never raises anything — a green rating does not lift a calculated value.

An editorial assessment of the evidence and safety situation — not a healing claim and not an individual recommendation. It does not replace veterinary advice.

DosageNo specific NRC 2007 / GfE 2014 requirement; lysine is the balanced first-limiting amino acid. Study/analogy guideline value roughly 20-50 mg leucine/kg BW/day as a targeted supplement around exertion/recovery; already amply present in high-quality ration protein (e.g. soybean meal).

AMG statusComplementary feed

FEI statusNot listed

SafetyVery safe

Evidencemoderate

Usage note

This content is for information and education. It does not replace veterinary diagnosis or treatment. If your horse shows signs of illness, consult a veterinarian.

“Nothing forced can ever be beautiful.”

Xenophon · On Horsemanship (c. 365 BC)

Equiterna is an intermediary platform for equine knowledge, marketplace and tools — not a veterinary-medicines dealer, veterinary practice or pharmacy. Compound information is study-attributed and free of healing claims. Legal framework: Regulation (EU) 2019/6 / TAMG (DE/AT), Feed Regulation (EC) 767/2009, FEI Prohibited Substances List, HWG.