Immunological methods involving pregnancy associated glycoproteins (PAG) are used for cattle pregnancy detection. The faults of these methods could be overcomed by using antibodies specific for each member of the PAG family. In order to differentiate between very similar proteins, preparation of antibodies specific for peptides is a method of choice. In this work, we summarize a series of considerations regarding peptide design and choose free access NCBI, Antigenicity Plot, EMBOSS Antigenic and Expasy tools to apply them. We design peptides specific for different reported PAG members and obtain the corresponding polyclonal antibodies for five of them.