Method for determining the quality of a semen of a vertebrate animal

A method for determining the quality of a semen of a vertebrate animal, the method comprising:

• measuring at least one absorption spectrum of a sample of said semen with a spectrometer;
• selecting a number n, with n≥4, of wave numbers σj (j∈[1;n]) where the wave numbers are spatial frequencies in the spectrum characteristic of semen of a breed or of species of said animal;
• determining from said at least one absorption spectrum of at least one of a value of the absorption Xj or a value of the second derivative of the absorption Xj″(j∈[1;n])for each of said n wave numbers σj (j∈[1;n]);
• and
• calculating a non-return rate Y at a predefined number of days from at least one of said absorption values Xj or the second derivative of the absorption Xj″ previously determined.