Energy balance studies with weaned lambs

A study was made of the efficiency of utilisation of lucerne by lambs weaned at 5 weeks of age. The comparative slaughter method was used to determine the gain or loss in body fat, protein, and energy. Nineteen crossbred lambs were used; 12 comprised an initial slaughter group and the remaining lambs were given fresh lucerne for 26 days at various levels of energy intake ranging from sub‐maintenance to ad libitum. All lambs mobilised fat and were in negative energy balance. Only the lamb on the sub‐maintenance level of nutrition was in negative nitrogen balance. The mean digestibility of the lucerne was 69.%, the mean metabolisability of the diet was 53.9%. At a given body weight, lambs fed on lucerne had more protein and less fat than those in the initial slaughter group. The metabolisable energy requirement for zero energy gain was 191.4 kcals/kg v? 24 hr, and the efficiency of utilisation of metabolisable energy for maintenance was 47.1%.