175 THE EFFECT OF NUTRITION ON OVARIAN FOLLICLE POPULATION AND PLASMA ANTI-MULLERIAN HORMONE CONCENTRATION IN ABERDEEN ANGUS HEIFERS

Abstract

The number of follicles in ovaries from cows is highly variable and has a high repeatability in females during the follicular waves. There is evidence that dietary restriction during pregnancy has a deleterious effect on fetal ovary reserve (Mossa et al. 2009). The anti-Mullerian hormone (AMH) is a member of the TGFβ superfamily, produced by granulosa cells from healthy growing follicles, and its concentration is correlated with the number of follicles recruited in the wave during the oestrous cycle and may be used as a biomarker of the follicle population in cattle. Our objective was to compare the number of follicles and AMH concentration in heifers born from cows that suffered food restriction during the first trimester of pregnancy (March to May of 2009) to heifers born from cows that did not suffer food restriction (March to May of 2010) in Bagé, RS, Brazil. Because the diet of these cows were pasture based when rain dropped from an average of 129 mm³ (from 2002 to 2008) to 64 mm³ (in 2009), these cows suffered food restriction. In 2010 rain averaged 83 mm³, reestablishing normal feeding conditions. Ovarian follicle count analysis and blood drawing was performed in 89 heifers born in 2009 and 131 heifers born in 2010. The counting of antral follicles (>3 mm) by ultrasound was only in heifers with absence of follicles >6 mm at the time of assessment. Cows from both years were also grouped into low (LFC) or high (HFC) follicle count. Plasma AMH concentrations (pg mL^–1) were determined by ELISA using human AMH/MIS Gen II commercial kit (Beckman Coulter, Brea, CA, USA) validated using plasma from cows of HFC and LFC, a castrated bull, and a pool of follicular fluid. Results were analysed using the Proc GLM procedure of SAS (SAS 9.2). Follicle LSmean was higher (P < 0.05) in heifers that did not suffer food restriction (19.09 ± 0.8) when compared with heifers born from cows that suffered food restriction (11.75 ± 0.75). Within no food restriction and food restriction groups, LFC heifers averaged 10.91 ± 1.21 and 4.16 ± 1.02 follicles, respectively, and HFC heifers averaged 27.28 ± 1.0 and 19.35 ± 1.0 follicles, respectively. Anti-Mullerian hormone concentration was higher (P < 0.05) for heifers born in 2010 (no food restriction; 77.24 ± 4.71 pg mL^–1) when compared with heifers born in 2009 that mothers suffered food restriction (30.89 ± 4.32 pg mL^–1). Furthermore, within heifers from the food restriction group AMH concentration was higher (P < 0.05) in HFC heifers (47.17 ± 6.2) when compared with LFC heifers (14.61 ± 6.0). However, there was no difference in AMH concentration between LFC and HFC in the no-food restriction group. In conclusion, dietary restriction during the first trimester of pregnancy might result in reduced follicle population in the female offspring; however, caution should be taken since animal variation is consistent. Furthermore, AMH concentration can be used as a biomarker for follicle population.

This research and scholarship for Ereno, Pupulim, Loureiro, Favoureto, and Castilho is from FAPESP.