The females are much smaller and more slender in build than the males. The females possess horns that spiral upwards, in the shape of a lyre, whereas males’ horns branch upwards and forwards and are frayed at the tips. Males can be distinguished by their dewlap (a fold of loose skin hanging down from the neck), which is unique among wild cattle. Both sexes have notched nostrils.2 Their average weight is 681–910 kg/795.5–1980 lb, average shoulder height is 170–190 cm/5.6–6.3 ft, their average length is 210–223 cm/7–7.3 ft, and their horns reach up to 80 cm in males (start to fray at about 3 yrs) 40 cm in females (spiral upwards–lyriform).1,2 The young are normally reddish with lighter coloured legs, and are greying at 5–6 months old. Adult males dark brown or black, adult females are grey in colour (giving them the common name, grey ox, and distinguishing them from other bovids in the region).2
Kouprey are known to live up to 20 yrs and have a gestation period of 8–9 months.3 Little else is known about their sexual maturation and primiparity and inter-calf interval period.