Green’s Dictionary of Slang

a great, hulking, undisciplined oaf.

c.1597		Shakespeare Henry IV Pt 1 II iv: Falstaff, you carried your guts away as nimbly, with as quick dexterity, and roared for mercy [...] as ever I heard a bull-calf.
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		‘Jon Bee’ Dict. of the Turf, the Ring, the Chase, etc.
1852		G.C. Mundy Our Antipodes I 228: The native [...] has as good a right to beef and mutton as John Bull-calf, the Anglo-Australian, has to kangaroo-tail soup.
1890		Bulletin (Sydney) 9 Aug. 15/2: Audiences have a down on an esquire, and he needs to be a perfect Lablache, whereas he is always a paltry drawing-room ‘Man the Lifeboat’ bull-calf.