Rambouillets for Western Ranges

Breeding sheep for the western ranges has depended largely on the Rambouillet, the breed that the State and Federal sheep-breeding specialists agreed to concentrate on when they organized the laboratory at Dubois and began the program of improving sheep for the West. The program includes systems of breeding aimed at locating strains in the Rambouillet that possess combinations of genes that will improve strains of Rambouillets with which they are crossed. Such breeding is between strains of the same breed; Rambouillets are not crossed with other breeds. In these efforts we have found that size and body weight are directly associated with satisfactory weights of lambs. At the Dubois laboratory, under range conditions, 303 Rambouillet ewes were studied for lifetime lamb production over a period of 5 years.- Ewes that averaged 119 pounds during their lifetime produced an annual average of 55 pounds of weanlings. Ewes that averaged 125 pounds produced 60 pounds of live lambs, and ewes averaging 135 pounds produced 69 pounds of live weaned lambs. In other words, Rambouillet ewes of good size and weight are needed for maximum production of lambs under range conditions.

We found it important to increase the length of staple in fleeces of Rambouillet sheep. This we accomplished by selecting rams and ewes of especially good length of staple. Mr. Nordby reported that their yearling progeny have consistently produced fleeces measuring one-third of an inch longer and averaging 0.45 pound more in clean wool than have progeny of the flock as a whole. What the improvement means in money is indicated by the fact that in 1943 Strictly Combing fleeces averaged $5.87 and the shorter French Combing fleeces brought only $5. All fleeces were grown under the same conditions at Dubois.

J. M. Jones and co-workers of the Texas Agricultural Experiment Station reported that smooth "C" type Rambouillet ewes produced a longer wool staple than did the wrinkled "B" type ewes of similar ages. They found that the staple length of 2,274 fleeces from "C" type averaged 2.28 inches, compared to 2.05 inches for 365 fleeces from "B" type ewes. Wool manufacturers, especially those making worsted goods, are willing to pay extra for fine wools having good staple length.

Two other desirable qualities that sheep breeders work for are open faces (that is, not excessively covered with wool), and absence of skin folds, which are unprofitable and a nuisance.

Open-faced Rambouillet ewes at Dubois have each produced more than 10 percent more pounds of live lambs a year than wool-blind ewes. In 1942 about 17 percent of the Rambouillet lambs had open faces, 40 percent had partly open faces, and 43 percent had wool over their entire faces, compared to 11, 40, and 49 percent, respectively, in 1941. The open-faced ewes weighed about 5 pounds more after shearing than those that were wool-blind. When open-faced rams were mated with open-faced ewes, about half of the offspring were opened-faced, and the rest had partly covered faces.

The Texas Agricultural Experiment Station and the Department have cooperated in analyzing the inheritance of the skin-fold character in Rambouillets. The results of that project show that culling the wrinkled sheep and selecting for mating only the animals without excess skin folds can be effective in gradually eliminating this monstrosity. The workers at Dubois have been successful in similar efforts. The average score for skin folds on the necks of all the Rambouillet weanling offspring from inbred lines changed from 2.2 to 1.7 in about 4 years, a score of 1 representing complete absence of skin folds and a score of 5 indicating maximum skin-fold development. Rambouillet lambs with practically no skin folds increased from 28 to 58 percent between 1938 and 1944.

Another example of what can be done through selective breeding is the research on the inheritance of defective jaws. In experiments conducted from 1937 to 1944 with Rambouillets having overshot jaws, the workers at Dubois found that when one or both parents were defective, 16.4 percent of the progeny were defective, compared to 1.4 percent of the progeny in a flock in which all the sheep of breeding age were normal. Sheep breeders, therefore, can best cope with the problem by not mating sheep having bad jaws.