The present invention provides ungulate animals, tissue and organs as well as cells and cell lines derived from such animals, tissue and organs, which lack expression of functional endogenous immunoglobulin loci. The present invention also provides ungulate animals, tissue and organs as well as cells and cell lines derived from such animals, tissue and organs, which express xenogenous, such as human, immunoglobulin loci. The present invention further provides ungulate, such as porcine genomic DNA sequence of porcine heavy and light chain immunogobulins. Such animals, tissues, organs and cells can be used in research and medical therapy. In addition, methods are provided to prepare such animals, organs, tissues, and cells.