F1 hybrid
The first-generation offspring of two different breeds or species.
Also: F1, first cross, F1 cross
F1 stands for first filial generation: the calves of parents from two different breeds, or sometimes two related species. F1 animals usually show the most hybrid vigour, and the Brahman and Hereford cross of the American South, called a tiger stripe, and the Hereford and Angus black baldy are well-known examples. F1 crosses between species occur too: in the Himalaya, yaks crossed with cattle give the dzo and dzomo, whose males are usually sterile, and the gayal is crossed with local cattle in Northeast India. Mating F1 animals with each other gives an F2 generation that is far more varied, which is why composite breeds take many generations to fix.