01733naa a2200169 a 450000100080000000500110000800800410001902400320006010000220009224501020011426000090021652012360022565000100146165000100147170000160148177300660149720755982017-09-14       1947    bl uuuu     u00u1 u    #d7 a10.2527/jas1947.62133x2DOI1 aGRANDSTAFF, J. O.  aRelation of kemp and other medullated fibers to age in the fleeces of Navajo and crossbred lambs.  c1947  aThe fleeces of 144 Navajo and 237 crossbred lambs born in 1940, 1941, 1943, and 1944 at the Southwestern Range and Sheep Breeding Laboratory, Ft. Wingate, N. Mex., were sampled at 28-day intervals from birth to one year of age. Samples of 100 fibers taken from the middle of the left side and thigh of each lamb were analyzed microscopically for kemp and other medullated fibers. From 28 to 364 days of age there was a reduction of 5.9 percent of kemp and 20.7 percent of other medullated fibers in the fleeces of Navajo lambs. For the crossbred lambs the decrease in both types of fibers was slightly greater than that observed for Navajo lambs. A major part of the change occurred between the ages of 28 and 84 days. Differences between ages, years, lambs within years, and also the interaction of years × ages were highly significant for both breeds. The differences between years were associated with a significant improvement in fleece quality of lambs produced between 1940 and 1944. Results of this study indicate that lambs which will have the most improved fleeces at yearling age can be selected with reasonable accuracy at about 112 days of age, when the fiber content of the fleece has reached a fairly constant level.  aLambs  aSheep1 aWOLF, H. W.  tJournal of Animal Sciencegv. 6, n. 2, p. 133-140, May. 1947.