Testicular development from three to 14 months of age were examined in Dorper (DD), Dohne merino (DM) and Meatmaster (MM) sheep breeds. Testicular measurements included testes volume (TV), diameter (TD), length (TL) and scrotal circumference (SC). Both TD and SC were highly repeatable and positively correlated with live body mass and other testicular measurements. Both SC and TD showed significant breed differences from three to ten months of age which disappeared later on. Non-linear equations were fitted for testicular measure= ments on age for each breed group. Testicular growth patterns are more similar in the mutton breed types (DD and MM) and differ from dual-purpose DM. This difference probably indicate earlier puberty in the DD and MM breeds.
In an attempt to account for body size differences, a SC: live body mass ratio is recommended as a practical selection criterion. A more rapid decrease in this ratio is indicated in the DD and MM breeds compared to the DM probably because of later puberty in the latter.

S. J Schoeman, G. C Combrink

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XI. Genetics of reproduction, lactation, growth, adaptation, disease, and parasite resistance., , 306–311, 1986
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