Kemp succession in N-type sheep.

Abstract

Frequencies of G1, G2, and G3 kemps in the fleeces of N-type strains have been analysed. The G1 frequencies have been related to fibre and follicle type differences. It has been shown that shedding is restricted to fibres formed by primary follicles, and that primary central follicles shed most of their fibres, while primary laterals shed few. Differences between genotypes in total kemp frequency were highly significant. In N/N and nr/nr there was more G1 kemp than in N+ in succeeding generations the difference between N/N and N+ was maintained, but the frequency in nr/nr only equalled that in N/+ . The N gene has a greater effect than the nr gene on shedding. The proportion shedding in the different pre-curly-tip fibres (those formed by primary central follicles) was related to their length and degree of medullation, and not to N-genotype. Genotype differences in G1 kemp frequency can be explained in terms of fibre type frequency differences.