Science: Lamb Control

Sheep raisers regard ewes as rather lazy beasts; most of them produce each year only one crop of lambs. The rest of the time they contribute nothing but wool to their owners’ support. Last week Armour & Co., which has a commercial interest in lamb chops, announced a method of making loafing ewes do double duty.

The trick is done with hormones. Unlike some other domestic animals (e.g., mares), a ewe does not come into breeding condition soon after lambing. If she “lambs” in spring, she is seldom ready to start again until the following fall. Working under an Armour grant, Professor Frank X. Gassner of Colorado A. & M. found that carefully measured and timed injections of a gonadotrophin a few weeks after lambing could make 100 ewes produce a fall crop of 65 to 85 extra lambs. A control group of 25 ewes without hormone injections was given a ram for company, but only one of them produced an out-of-season lamb.

Since the injections cost only about 25¢ each, Armour hopes that this method will make sheep a more profitable U.S. crop.