This experiment was concerned with the artificial rearing of lambs, so as to obtain high growth rates, similar to those of naturally reared animals (32-35 kg in 90-120 days). Three replacement [image]milks (3,4 and 5) were compared with two reference milks (1 and 2): 1) ewe''s milk; 2) [image]cow''s milk reconstituted from a full cream milk powder; 3) [image]20-0 milk reconstituted from a powder including 20 p 100 tallow and 80 p 100 dried skim milk; 4) [image]30-0 milk (powder including 30 p 100 tallow and 70 p 100 dried skim milk); 5) [image]-20-10 milk (powder including 20 p 100 tallow, 10 p 100 dehydrated potato starch and 70 p 100 dried skim milk). The [image]milks 2, 3, 4 and 5 had the same dry matter content as the ewe''s milk, i.e. 180 g dry matter per litre. With each of these 5 [image]milks , 12 lambs (2 groups of six lambs each) were fed ad libitum from birth to weaning at 7 weeks; from 1 week until the end of the experimental period (9 weeks) each group received lucerne hay and a concentrate, provided ad libitum. The average live weight gain from birth to the end of the experiment and that from birth to weaning, was significantly higher for the lambs fed on ewe''s milk (I); although one group of 6 lambs of lot 4 ([image]30-0 milk ) achieved a similar growth rate. However, at 14 weeks the average live weights of groups 1, 3 and 4 were similar. There were very small differences between the amounts of liquid consumed by the 5 groups: only the amount of [image]30-0 milk consumed was significantly smaller than that of ewe''s milk. The daily consumption of concentrates was low until the 4th week; it reached 100-150 g per head at 6 weeks, and then increased greatly during the 7th week when the liquid feeding was reduced. The concentrate/hay ratio amounted to 1 until the 6th week, to 2 in the 7th week, and reached 3. 5 in the 9th week. The dry matter intake per 100 kg live-weight was rather higher during the first 2 weeks (4-4. 5 kg), decreased to 3-3. 5 during the 4th and 5th weeks, and went up again to 4-4. 5 kg after weaning. The gross efficiency of conversion of the [image]milk% energy consumed into live weight gain was between 6 and 9 kg; there were important differences between the 5 lots. In the same live-weight range, there was a strong relationship between the lambs'' growth rate and the gross energy consumption as [image]milk . The lambs fed on replacement milks (lots 3, 4 and 5) were subject to scouring and [image]bloats , the incidence of these disorders being related to the proportion of tallow (or tallow + starch) in the powder. It is not impossible to achieve as high growth rates from birth to slaughter with replacement milks as with ewe''s milk, but this artificial rearing technique ought to be associated with the early weaning of lambs.