| Abstrakt: |
Data on growth in Karakul, Karakul × Corriedale, and Karakul × Blackfaced Highland lambs from birth to 52 weeks of age and a comparison of these with data from lambs of the mutton breeds of sheep handled under farm flock conditions are presented. Because of the infrequency of twin births in the Karakul and Karakul crossbred flocks at the United States Department of Agriculture, Beltsville Research Center, Beltsville, Md., only single lambs of the Hampshire, Shropshire, Southdown, and Corriedale breeds at this same station are included in the study. The data are shown graphically as growth curves. Analyses of these data show that: 1.The Karakul and Karakul crossbred lambs were more nearly like the Hampshire lambs than those of the other mutton breeds in size at birth, as shown by similarity of birth weights.2.Birth weights of Karakul male lambs ranged from 9.3 to 12.8 and of females 6.3 to 12.8 pounds, an average of 11.1 and 10.2 pounds respectively. The Karakul × Corriedale female lambs also averaged 10.2 pounds and those of Blackfaced Highland breeding 10.3 pounds at birth.3.The growth curves indicated quite definitely that the Karakul and crossbred lambs were smaller than the Hampshire and larger than the Southdown lambs at practically any age from birth to 52 weeks. The growth trend in all the breeds was similar.4.After adjusting for differences in the average birth weights between breeds, the Karakul lambs in rate of growth showed greatest similarity to the Corriedale lambs, followed in order by the Shropshire, Southdown, and Hampshire breeds. Although the mean birth weights of the Karakul and Hampshire female lambs were practically the same numerically, the rate of growth was much slower for the Karakul, resulting in a highly significant difference in mean gains for the 13-, 26-, and 52-weeks periods. The Karakul × Blackfaced Highland and the Karakul × Corriedale lambs ranked in the same order as the Karakul with respect to their similarity to the Corriedale, Shropshire, Southdown, and Hampshire breeds in rate of growth.5.The ability of Karakul and Karakul crossbred lambs to grow at a rate comparable with those of some of the best mutton breeds is of economic importance to breeders who find it necessary to raise many of their lambs with inferior fur for meat purposes. |
