The effects of energy and crude protein (CP) supplementation on feed intake of lactating ewes grazing native pasture (veld) were studied during two autumn (1981 and 1982) and two spring (1983 and 1984) lambing seasons. The CP content of the diet selected by oesophageally fistulated sheep was higher in summer (1983: 10,8-13,3% and 1984: 14,9-19,8%) than in winter (1981: 5,9-8,3% and 1982: 6,7-8,7%). Digestibility of organic matter (OMD) of the diet was also higher in summer (1983: 58,5-64,0% and 1984: 56,6-65,6%) than in winter (1981: 54,2-58,8% and 1982: 52,4-56,4%). Different levels of energy and / or CP were provided daily via rumen fistulae to the ewes. Herbage intake of lactating Merino and Dorper ewes was not increased in response to CP during the winter (1981 and 1982), but decreased when energy was supplemented. Supplementation of energy plus CP increased herbage intake slightly. The Dorper ewes were 22% and 28% respectively heavier than the Merino ewes in 1981 and 1982. Despite similar amounts of herbage ingested by the two breeds (DOM intake; DOMI / day), lactating Merino ewes had a higher herbage intake per metabolic size (DOMI / W kg0.75/ day). In summer, herbage intake of lactating Dorper ewes was not increased by supplementary CP (1983), but decreased by supplementary energy (1983 and 1984). Herbage intake (DOMI / W kg0.75/ day) of lactating Dorper ewes was substantially higher in summer. Total intake (herbage plus supplements) by the lactating ewes corresponded with animal performance in the respective treatments and seasons.
