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Kikuyu pasture was grazed continuously for 12 months by 20 dry and 40 producing South African Mutton Merino (SAMM) and Merino ewes at a stocking density of 23 ewes ha -1 . Supplementary sweet lupin seed was supplied to one group of producing ewes of each breed during pregnancy and lactation at a rate of 0.5% of the liveweights of the ewes. Rumen fluid samples for the determination of pH, volatile fatty acids (VFA), and ammonia-nitrogen (NH 3 -N) were collected from rumen-fistulated wethers corresponding to the periods of late pregnancy and early lactation of ewes. Rumen NH3-N concentrations (8.7 mg 100 ml -1 and 5.4 mg 100 ml -1 ) were low during both periods of sampling. Rumen VFA concentrations (12.3 mmol 100 ml -1 and 9.2 mmol 100 ml -1 )were within normal ranges. Supplementation significantly increased blood urea concentration of ewes. Supplemented ewes lost less weight than the unsupplemented ewes (P 0.02) during the experimental period. Pregnancy (P 0.001) as well as lactation (P 0.0001) reduced greasy wool production. Supplementation increased birthweight of lambs by 21% (P 0.0007). Rumen parameters indicated no severe deficiency in either protein or energy intake. A lack of response in wool and lamb growth due to lupin supplementation was primarily A98055Received 2 1 October 1998; accepted 16 July 1999 ascribed to a high CP degradability of lupin seed. Production of the different breeds was in accordance with their respective genetic potential.

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Summary. Three feeding trials compared production of lambing ewes grazing stubbles and fed different combinations of energy and protein supplements as loose licks. Each experiment had 2 treatments in a 2 x 2 factorial design. Experiment 1 compared urea (12.5 g/ewe. day) with fish meal (100 g/ewe. day) when fed with molasses (100 g/ewe. day) for 38 days during late pregnancy. Fish meal increased liveweight gain (from 2.0 to 5.7 kg) and wool growth (20%) but urea had no effect. In experiment 2, urea (12.5 g/ewe. day) was fed in combination with molasses (200 g/ewe. day) or barley meal (200 g/ewe. day) for 63 days during late pregnancy (last 6 weeks) and early lactation. Ewes supplemented with the barley–urea combination gained 5.6 kg during the last 6 weeks of pregnancy compared with 0.40 kg for barley and the 1.02 and 1.34 kg weight loss for ewes receiving molasses and the molasses–urea combination, respectively. Experiment 3 compared urea (12.5 g/ewe. day) with sweet lupin meal (106 g/ewe. day) when fed with barley meal (200 g/ewe. day) for 56 days during late pregnancy (last 4 weeks) and lactation. Sweet lupin meal improved the liveweight change of ewes during pregnancy (from 160 to 200 g/ewe. day) as well as the birth weight of lambs (400 g) but urea had no effect. The performance of lambing ewes grazing low-quality pasture at a high stocking density (>4.5 ewes/ha) for a long period (>130 days) can be improved by relatively low amounts of supplements such as fish meal, sweet lupin meal and barley–urea.