Here is an excellent primer on the genetics of horns in our sheep. It is a very simplistic model and works ONLY if none of the ewes in a flock have horns. It also assumes there is only one gene for horns. We now know that is not the case; there also is a gene for scurs. It was written by Dave Thomas, Professor of Sheep Genetics and Management, University of Wisconsin-Madison and is printed here with his permission: _________________________________________________________________ Inheritance of horns is not as simple as the genetic textbooks make it seem. It is complicated by the fact that inheritance can be different in males and females and in different breeds. However, generally speaking, horns are recessive and polledness is dominant. If I let H = the dominant gene for polledness and h = the recessive gene for horns, the following situations can result:
HH = animal has 2 polled genes and is polled Hh = animal has 1 polled and 1 horn gene and is polled because the polled gene is dominant hh = animal has 2 horn genes and is horned If you purchase a polled ram, he can be HH or Hh. If he is HH, all his progeny will be polled because all the progeny will have at least one H gene. If he is Hh, he can produce polled or horned offspring depending upon the type of ewes he is mated to. Blackbelly ewes are usually polled, but they can still carry the horn gene. They just don't express the horn gene. Mating a polled ram that is a carrier of the horn gene (Hh) to different types of ewes will give you the following types of progeny: Ram x Ewe = Progeny Hh x HH = 50% HH, 50% Hh = all lambs polled Hh x Hh = 25% HH (all polled), 50% Hh (all polled), 25% hh (males horned, females polled) Hh x hh = 50% Hh (all polled), 50% hh (males horned, females polled) If the polled ram has a horned parent, then the ram is Hh. If the polled ram has produced lambs and at least one was horned, then the ram is Hh. If the ram has been mated to several ewes in a flock where horned males are found and he has never produced a horned lamb, then you have some confidence that he is HH, however, there is still a chance that he is Hh. Carol _______________________________________________ This message is from the blackbelly mailing list Visit the list's homepage at blackbelly@lists.blackbellysheep.info http://lists.blackbellysheep.info/listinfo.cgi/blackbelly-blackbellysheep.info
