A Study of the Protein Requirements of Fattening Feeder Lambs

A total of 297 western feeder lambs have been used in three experiments. A 3 × 3 factorial arrangement of 9 lots of 11 lambs each was used to determine the value of rations with three levels of total protein, air-dry basis, and various proportions of alfalfa hay and corn silage. Performance was measured in terms of rate of gain, feed required per 100 lb. of gain, and degree of finish. The lambs fed rations with about 11.8 percent total protein made more rapid gains but were not as fat as those fed rations containing 10.0 and 11.0 percent protein. There was little difference in feed efficiency of lambs fed rations with the various percentages of protein. The feeding of different amounts of alfalfa hay with a full feed of corn silage did not significantly affect the rate of gain or degree of finish. Lambs fed corn silage as the only roughage made more efficient and economical gains than those fed 0.75 or 0.50 lb. of hay and a full feed of silage. Corn silage has a high value when full fed with 0.50 lb. of alfalfa hay per lamb daily. A better feed-lot performance is obtained when a small amount of hay is fed than when corn silage is fed as the only roughage.