Bovine hereditary zinc deficiency: lethal trait A 46. 
Bovine hereditary zinc deficiency, also referred to as Adema disease, is an autosomal recessive disorder which results in inadequate amounts of zinc being absorbed from the gastrointestinal tract and leads to a number of clinical abnormalities.  Using semen from a homozygous affected bull and obligate heterozygote cows in embryo transfer studies, 7 offspring were obtained.  These included 5 affected calves and 1 heterozygous carrier; the seventh calf died within 48 hours of birth undiagnosed.  One unaffected, unrelated bull calf was raised as a control.  All the calves were raised and maintained under similar management conditions designed to minimize secondary complications that would obscure the clinical and biochemical observations of a zinc deficient state.  The first clinical manifestation of zinc deficiency was diarrhea, followed by skin lesions, poliosis, and a decreased ability to sustain a suckle reflex.  Trace mineral analysis of plasma blood samples revealed that plasma zinc concentrations of all the calves were normal at birth; however, they gradually declined in affected calves over the course of 3-8 weeks postpartum to below 0.5 ppm.  Biochemical analysis of serum samples showed alkaline phosphatase activity consistently paralleled changes in the plasma zinc concentrations.  The oral administration of zinc acetate caused a reversal of all clinical, biochemical, and histologic abnormalities in affected calves.  The study of these affected calves allows further insight into the biological role of zinc as well as provides an animal model for the continued investigation of the human homologue acrodermatitis enteropathica.