Assessment of Reproduction | College of Veterinary Medicine at MSU
This is the info I use and a photo of nanogram scale.
0-2 nmol/L Baseline concentrations too early to estimate ovulation
3 – 6 nmol /L Minimum 2 days before ovulation expected however result of 3 – 4 nmol/L may persist for a week or longer before increasing. Earliiest estimating breeding 4 – 6 days but could be longer (re test needed)
7 – 12 nmol/L Minimum 1 day before ovulation. Estimated window for breeding 3 – 5 days but could be longer ( re test recommended)
13 – 18 nmol/L Ovulation impending or just occurred. Estimated breeding window 2 – 4 days
19 – 31 nmol/L Ovulation recently occurred. Estimated breeding window 1 – 3 days
32 – 64 nmol/L Ova have matured, optimal potential for fertility. Estimated breeding window 0 – 2 days
65 – 90 nmol/L Ova have matured but aging, decreased potential for fertility. Breed at once
Above 90 nmol/L Too late