Use of PDE V inhibitors for improved fecundity in mammals

This invention relates to a new use of certain substances in mammals. More specifically, it relates to the use of cyclic guanosine 3′, 5′-monophosphate phosphodiesterase type five (cGMP PDE V) inhibitors to increase fecundity in mammals. The invention relates to the use of a cyclic guanosine 3′,5′-monophosphate phosphodiesterase type five (cGMP PDE V) inhibitor for increasing fecundity in a mammal by one or more of (a) promoting the growth of an oocyte, zygote, blastocyst, embryo and/or foetus, (b) increasing the rate or probability of survival of an embryo and/or foetus and (c) increasing the birth weight of a progeny, or for increasing milk productivity.