Milk and herbage intakes and growth rate of lambs from 32 to 130 days of age raised on natural pasture in the semi-arid Negev

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 ± 0.16 l d−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−1from herbage. Thus, 18.8% of the total energy intake was retained as body energy by the lambs; about 22.4% was retained from days 32 to 102 days but it decreased to 5.9% by 116 days.