Rare term for a horse's trot; used in equestrian contexts. The more common word is 速歩 (はやあし).
In equestrian terminology, だく足 refers to a type of trot.
Rare kanji spelling; the first character だく is a kokuji or specialized character used in horse-riding contexts.
Alternate rare kanji spelling using 跑 (running/galloping).
Alternate rare kanji spelling; 諾 is likely ateji.
The exact derivation is uncertain. The first element だく may be related to the sound of hooves or a mimetic word, and 足 means 'foot/leg'. The kanji だく is a specialized character for this term.