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We determined milk and herbage intakes and growth rate of 18 ram-lambs from 32 to 130 days of age when sucking ewes that were grazing natural pasture in the semi-arid Negev. Milk intake decreased from 0.77 +/- 0.161d(-1) at 32 days of age to zero milk intake at 116 days of age, whereas herbage digestible organic matter intake increased from 237 36 g d(-1) at 32 days to 559 +/- 64 g d(-1) at 74 days, after which age it leveled off. Body mass at 32 days was 8.32 +/- 1.04 kg and at 130 days was 24.02 +/- 3.65 kg for an average daily gain of 159 g d(-1). Of the 159 g d(-1), 52.0 g d(-1) were body solids, which were composed of 32.2 g d(-1) of fat and 19.8 g d(-1) of protein. Energy retention averaged 1.72 kJ d(-1), and total energy intake averaged 9.17 kJ d(-1); 2.33 kJ d(-1) from milk and 6.84 kJ d(-1) from herbage. Thus, 18.8% of the total energy intake was retained as body energy by the 41 lambs; about 22.4% was retained from days 32 to 102 days but it decreased to 5.9% by 116 days. (c) 2004 Elsevier B.V. All rights reserved.