The present invention relates to genetically modified animals for the production of recombinant proteins. Particularly, pig's seminal vesicle and sexual accessory glands are genetically transformed to recombinantly produce such protein of interest in the semen of sexually mature pigs. Even complex proteins can be produced in large quantities and purified. The present invention also relates to mammal seminal gland tissue-specific promoters that can be used to make gene constructs including a protein-coding sequence not natively associated with the promoters or a sufficient portion of the promoter such that the portion actuates the preferential expression of the protein- coding sequence in the seminal vesicle and/or accessory tissues of mammals.
