The only justifiable reason for early weaning of lambs is to improve the overall efficiency of the production system. It can be more efficient to put the feedstuffs directly into the lamb, rather than indirectly through the ewe in the form of milk. Increased efficiency in this case is dependent on the physiological age of the lamb, the relative costs of the two ewe diets, the costs of the lamb diet, the rate of gain of the lamb, and other benefits that might accrue, such as earlier marketing of lambs while the price is higher, enhanced opportunity to rebreed the ewe for a second lamb crop, and the opportunity to operate a larger production unit without increasing acreage.