Lactating red deer (Cervus elaphus) hinds and their calves were rotationally grazed on Lotus corniculatus or perennial ryegrass/white clover pasture at an allowance of 12 kg DM/hind/day during summer 1996 in Palmerston North, New Zealand. Half the hinds suckled pure red deer calves and half suckled hybrid (0·25 elk[ratio ]0·75 red deer) calves. Measurements were made of the diet selected, voluntary feed intake of the hinds and liveweight changes of the hinds and calves.

Lotus corniculatus and perennial ryegrass constituted c. 90% of green material in the diet selected on the respective forages. Total nitrogen (N) content and organic matter digestibility (OMD) were higher for Lotus corniculatus than for perennial ryegrass/white clover pasture. Lotus corniculatus contained 21 g condensed tannin (CT)/kg dry matter (DM), whilst pasture contained only traces of CT (1·6 g/kg DM).

Hinds grazing Lotus corniculatus tended to have higher voluntary feed intake, and calf liveweight gain (485 v. 399 g/day) and weaning weight (52·6 v. 48·1 kg) were greater than for deer grazing perennial ryegrass/white clover pasture. Hybrid calves grew faster than pure red deer calves (P<0·01), with hybrid calves grazing lotus having very high liveweight gain (c. 520 g/day). Liveweight gain of hinds grazing Lotus corniculatus also tended to be higher (91 v. 20 g/day) than for hinds grazing perennial ryegrass/white clover pasture. CT was bound more strongly during chewing by red deer than had been found in comparable studies with sheep and the nutritional significance of this is discussed. Nutritional reasons for the superior performance of deer grazing Lotus corniculatus are discussed.