The affix ap comes after the verb śri 'to flow' in the sense of impregnating (the covering of cows etc.).,
This debars घञ्. The word प्रजनं means 'the first covering of a cow by a bull'. As गवामुपसरः 'impregnation of cows'; पशूनामुपसरः 'impregnation of cattle'.,