Brachygnathia in Simmental Cattle

Brachygnathia is a deficit in mandibular length causing the incisor teeth to meet the upper dental pad behind its anterior angle. It is a problem to breeders of both red and black Simmental cattle, as wellas other breeds. The condition has been considered inherited as a simple autosomal recessive trait. It has also been observed as one part of a lethal, multiple-defect syndrome in Simmentals caused by the calf being born with an extra chromosome (Trisomy17). Intrauterine infectionwith bovine viraldiarrhea-mucosal disease virus (BVD-MD)also can cause the defect, but usually in this case the calf is also born with a variety of additional problems. In Angus cattle, the defect has also been observed accompanying osteopetrosis, an inherited bone defect. Selective culling and breeding practices designed to remove an undesirable genetic trait have been unsuccessful for a number of producers of both red and black Simmentals. For that reason, we have been studying the inheritance of this condition in more detail