Green’s Dictionary of Slang

(Aus.) cattle thieving; thus cattle-duff v.; also attrib.

1879		Star (Canterbury) 15 Sept. 2/7: If there was any foundation for the cattle-duffing story [...] his proper place was in the dock.
1886		Melbourne Punch 15 July n.p.: Cattle duffers on a jury may be honest men enough, / But they’re bound to visit lightly sins in those who cattle duff.
1888		‘Rolf Boldrewood’ Robbery Under Arms (1922) 77: I don’t know whether cattle-duffing was ever done in New South Wales before on such a large scale.
1908		G. Seagram Bushmen All 33: Details of crimes such as [...] bushranging exploits, cattle duffing feats and pugilistic encounters.
1912		Truth (Wellington) 26 Oct. 7/6: [headline] Cattle Duffing.
1958		R. Ward Aus. Legend 4: An occasional unknown workman [...] by superior industry, temperance, or skill in cattle-duffing, became a ‘shepherd king’.
1965		R.H. Conquest Horses in Kitchen 213: This used to be great cattle-duffing country in the old days.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Duffer. A cattle thief. Thus cattle duffing is stealing cattle.