If the quality of the oocyte, in general, is good; larger follicle=larger CL, larger CL=higher progesterone level. More progesterone, better embryonic nutrition, recognition of pregnancy, elongation and per se conception rate.

There are some old articles about that. Please find attached.

Thank you dear Osvaldo

The answer by Osvaldo Bogado Pascottini is very good, but I would add one caution. In some estrous synchronization procedures, the life of the dominant follicle can be extended to the point that the oocyte deteriorates even though the follicle diameter is increasing.  So be careful not to include treatments that might extend follicle growth beyond the norm if you are studying this problem.

Thank you Dr. Britt. I wonder if there is a cut-off point for the maximal diameter of the MGF at AI after which the probability of conception would be decreased.

I do not recall the exact number, but I think if the ultrasound diameter is much over 20 mm then the follicle is probably getting "old". It may vary some among breeds, so that is important to consider.

Jack

True Jack, but also there is a positive association between the milk production level of the cow and the diameter of the pre-ovulatory follicle. There is not getting old, but maybe with lower quality due to high NEFAs levels =)

Regards Osvaldo, Do you confirm any asscociations between levels of NEFA in follicular fluids and follicular sizes? I think Dr Britt can help us in this topic too....

The positive correlation between milk production and follicle diameter is probably related to the higher metabolic clearance rate of steroids in higher producing cows. This lowers progesterone and estradiol and their inhibition on gonadotropins and the follicle is stimulated to grow larger. Dr. Wiltbank's group at the University of Wisconsin has published several papers on this. The question about NEFA will depend a lot on the postpartum period, but  in general as NEFA increases the interval to first ovulation is prolonged.