Some aspects of gene dosage effects in N-type sheep

Abstract

In 1929 Dr. Dry at Massey College started simple breeding experiments on the inheritance of fleece characters in the New Zealand Romney. These included pronounced hairiness, i.e., substantial medullation in coarse fleeces. In newborn lambs with coarse hairy birthcoats, long coarse, hairy fibres, called by Dry Halo-hairs (1933, 1935) project above the rest of the birth coat. Lambs born were graded on halo-hair abundance (Dry 1933, 1935) Grade I having no halo-hairs on the back and grades II, III, IV, and V an increasing number up to Grade VI, which had many. Experiments showed that in these lambs halo-hair abundance was inherited in multifactorial fashion. However in 1931 a search for lambs with many halo-hairs was made in several stud Romney flocks, this leading to the discovery of oligogenes producing a high abundance of halo-hairs. One ram was received from Mr. N. P. Nielson of Tiakitahuna and became the founder of a stock carrying an incompletely dominant gene producing a great abundance of halo hairs in the birthcoat far surpassing that shows by Grade VI. lambs showing this birthcoat were called N-grade in gratitude to Mr. Nielsen. The same gene appears to have been brought on to the College property in 1929 in a hairy ewe from which the foundation N-grade ram of the Massey-N stock was descended.