Adequate colostrum supply is one of the most important factors affecting neonatal health and development. It is known that leukocytes from colostrum, including polymorphonuclear neutrophil granulocytes, are able to migrate from mother to neonate via colostrum ingestion. The aim of this work was to determine the levels of PMN in ovine and canine colostrum and to test whether these cells are able to perform their immunological tasks, in particular the formation of NETs, even after passage of the colostrum. Furthermore, the course of PMN levels in the sheep colostrum and transit milk was recorded over the first 12 h after birth and in the dog at the time of birth. This showed that the levels of PMN in the sheep remained approximately constant during the first 12 h after birth. Sheep and dog colostrum-derived PMN were first collected and counted by density gradient centrifugation and, after stimulation with N. caninum tachyzoites and other stimuli, examined by chromatin staining and antibody-based immunofluorescence of NET-specific structures, including neutrophil elastase (NE) and global histones (H1, H2A/H2B, H3, H4), and by scanning electron microscopy (SEM) analysis. Here, for the first time, the ability of ovine and canine colostrum-derived PMNs to produce NETs against the abortive apicomplexan parasite Neospora caninum, has been shown.