1. Sixteen lambs were used to compare two methods of administering various protein supplements to weaned lambs. In one method the protein supplement was mixed with the dry feed, consisting mainly of rolled barley, so that it passed to the rumen. In the second method the supplement was suspended in water which the lambs were trained to suck from a bottle; the suspension then passed directly to the abomasum by way of the oesophageal groove and so escaped rumen fermentation.

2. When the protein supplements were given in amounts that provided less than the estimated protein requirement of the animals, giving the liquid suspension led to significantly lower urinary nitrogen excretion (P < 0.001), greater nitrogen retention (P<0.05) and greater live-weight gain (0.05<P<0.1) than giving the feed in the dry form.

3. The body-weight gain was greater with white fish meal than with casein (P<0.05) and soya-bean meal (P<0.001), whichever method of feeding was adopted. There was no significant interaction between method of feeding and protein source, but the faecal nitrogen excretion was highest when soya-bean meal was given in liquid suspension.

4. From a regression of nitrogen retention on nitrogen intake with lambs receiving the basal ration only, it was calculated that the improvement in retention of the protein supplement effected by giving it in liquid suspension was 31 % for casein, 27 % for fish meal and 24 % for soya-bean meal.