Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 26, 2001
Publication Date: May 20, 2001
Citation: McCoard, S.A., Wise, T.H., Ford, J.J. 2001. Dynamics of fetal and neonatal ovarian development and follicle maturation in Meishan and White Composite gilts [abstract]. Proceedings Sixth International Conference on Pig Reproduction, Columbia, Missouri, p. 26. Technical Abstract: This study compared the dynamics of the oocyte population during fetal and neonatal life in gilts derived from MS and White Composite (WC) primiparous sows differing in ovulation rate. Ovaries were recovered at 60-105 days postcoitum (dpc) and 1-25 days postpartum (dpp). Fetal WC gilts tended to have heavier ovaries than MS gilts but ovarian weight diverged postnatally resulting in heavier ovaries in MS gilts at 25dpp. In both breeds, total oocyte number increased rapidly from 60dpc reaching a peak at 90dpc, declined rapidly thereafter, resulting from atresia predominantly within egg nests, reaching 22% and 34% of maximal numbers by 25dpp in WC and MS gilts, respectively. Breed differences in total oocyte number were not significant at any age. Overall, the number of developing follicles per CS was greater in MS than WC gilts during postnatal life. Similar differences were observed for the proportion of oocytes/follicles in each developmental stage. These results indicate that oocyte number is unlikely to influence subsequent ovulation rate, but more advanced follicle development in MS gilts supports early onset of puberty in this breed. Greater follicle numbers at a more advanced stage of development is consistent with observations in adult MS ovaries associated with increased ovulation rate. This study highlights the important developmental events that occur during late fetal and neonatal life that prepare the ovarian environment for early onset of puberty and subsequent ovulation in MS gilts.