Why is there so much variation in ovary size, ovarian reserve, and AFC?
There is evidence suggesting that maternal nutrition or disease may contribute to high variation. In a beef heifer study, follicular development of the fetus was inhibited when the dam was fed 60 percent of her energy requirement shortly before conception and during the first trimester. The first trimester is when the peak in number of follicles and oocytes in the fetal ovary.
The offspring from control dams and restricted dams had similar birth weights but the offspring from the restricted dams had 60 percent lower AFC.
In a study on a commercial dairy farm, Holstein cows with a high number of somatic cell count (SCC) measurements greater than 200,000 produced daughters with lower serum AMH, smaller ovaries, and fewer high quality oocytes, and reduced ovarian function than cows with lower SCC measurements.
The role of maternal nutrition and disease on offspring fertility should be a hot topic for research and lead to the development of novel prenatal therapeutic methods and management programs.
* Reference: Ireland, J. J., G. W. Smith, D. Scheetz, F. Jimenez-Krassel, J. K. Folger, J. L. H. Ireland, F. Mossa, P. Lonergan, and A. C. O. Evans. 2011. Reproduction, Fertility and Development 23:1-14.
Source: W.H. Miner Agricultural Research Institute’s Farm Report, August edition