Does a season on full curled rams select for small-horned rams?
by Valerius Geist, PhD

Horn-growth is expressed maximally under exceptionally favorable food conditions, when rams grow to their genetic maximum in body size. . . . Then and only then is the length of the horn a function of heredity. . . . Horn size is very sensitive to environment and not very sensitive to heredity. Consequently, in rams of average body mass, [a ram’s] horn growth has little relationship to its genetics. Maximum horn size then is a function of a few good summers plus the good luck of not being killed by predators or an accident.

. . .When rams born and raised in different home range groups mix in ram groups, as they do [maximizing genetic variability with a ram group], a ram with rapid horn growth may be inferior genetically in horn growth to ram originating in another home range group with poorer body development [because of differences in nutrition among geographically separate ewe groups]. . . .

You have, in the past with the full curl rule, harvested only a fraction of the legal rams – as it should be!
The fear, that taking a large fraction of full curled rams will diminish horn growth potential, is well meaning, but unfounded. It would be a different matter if rams were severely harvested at the ¾ curl stage.

Sincerely,

Valerius Geist PhD., P. Biol.
Professor Emeritus of Environmental Science
The University of Calgary