REDR2010 Reproduction in Domestic Ruminants VII Managing Fertility in Domestic Ruminants (3 abstracts)
Causes and consequences of the variation in the number of ovarian follicles in cattle
ACO Evans 1 , F Mossa 1 , T Fair 1 , P Lonergan 1 , ST Butler 2 , AE Zielak-Steciwko 3 , GW Smith 4 , F Jimenez-Krassel 5 , JK Folger 5 , JLH Ireland 5 & JJ Ireland 5
1School of Agriculture Food Science and Veterinary Medicine, and the Conway Institute, College of Life Sciences, University College Dublin, Belfield, Dublin 4, Ireland; 2Moorepark Dairy Production Research Centre, Teagasc, Fermoy, Co. Cork, Ireland; 3lnstitute of Animal Breeding, Faculty of Biology and Animal Science, Wroclaw University of Environmental and Life Sciences, 50-375 Wroclaw, Poland; 4Laboratory of Mammalian Reproductive Biology and Genomics, 5Molecular Reproductive Endocrinology Laboratory Department of Animal Science, Michigan State University, East Lansing, Michigan 48824, USA
Summary. In cattle we have noted that the antral follicle count (AFC, follicles ≥3 mm in diameter) varies greatly among animals (from 5 to 50), is repeatable within animals, and is highly correlated with the total number of healthy follicles in ovaries. Also, animals with low AFC have higher serum concentrations of FSH and LH, but lower concentrations of Anti-Mullerian Hormone, progesterone and androgens than animals with high AFC. We have investigated the effect of maternal environment during gestation on their offspring AFC by restricting maternal nutrition to 60% of maintenance requirements (compared with 100% in controls) during the first third of gestation. Calves born to nutritionally restricted mothers had 60% lower AFC compared with calves born to mothers fed control diets. In other studies we have evidence to indicate that fertility may be compromised in animals with low AFC due to effects on oocytes, progesterone and the endometrium compared with animals with high AFC. To examine this directly we assessed AFC in post-partum dairy cows and found that cows with a high AFC had higher pregnancy rates, shorter calving to conception intervals and received fewer services during the breeding season compared with cows with a low AFC. In addition, the high variation in follicle numbers in adults may not only be reflective of reproductive disorders and suboptimal fertility, but there is evidence to indicate that it may be associated with alterations in the function of other non-reproductive systems (e.g. cardiovascular) that may have profound effects on the animal's health and welfare.
© 2010 Society for Reproduction and Fertility
Volume 7
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