107 Anti-Müllerian hormone plasma concentration in alpacas as a predictor of their ovarian reserve

In mammals, the ovarian follicular reserve is highly variable between individuals and impacts strongly on ovarian function and fertility. Currently, the best endocrine marker of this reserve in human, mouse, and cattle is anti-Müllerian hormone (AMH). However, there are few studies on AMH in camelids. The objectives of this study were to determine whether AMH could be detected in the blood plasma of female alpacas and to assess its relation with their ovarian reserve. In experiment 1, the commercially available mice AMH-ELISA kit (AnshLab rat/mouse ASL 113) was used to measure serum AMH concentrations in alpaca per the kit’s instructions. To validate the alpaca serum AMH assay, parallelism of different doses of the following sources of alpaca sera (n = 5) or follicular fluid (n = 5) with the AMH standard curve were evaluated; plasma castrated male alpacas (n = 5) and plasma female rat (n = 5) were used as negative and postive controls, respectively. The intra- and interassay coefficients of variability were 2.9 and 3.1%, respectively. Serial dilution of sample yielded a straight line with a slope of 1.0 (r² = 0.99). In experiment 2, the antral follicle count (AFC) was determined in ovaries (70) obtained at abattoirs from 35 females alpacas (4 years old). Blood samples were taken by jugular venipucture before the alpacas were killed. The ovaries were collected immediately thereafter and the AFC was estimated by counting follicles in each histological section, using the oocyte nucleus as a marker and employing a correction factor. The average value for AFC per ovary was used to classify alpacas into low AFC (≤10 follicles) and high AFC (≥25 follicles). Females with intermediate AFC (11–24 follicles) were not considered for this study. The blood sample previously taken was used to determine the correlation between AFC groups and AMH. Average weigh, height, and length for both ovaries in the low- versus the high-AFC group were compared. The AMH concentrations in the different volumes of alpaca plasma and follicular fluid were parallel with the AMH rat kit standard curve (AMH values were between 0.022 and 2.036 ng mL⁻¹) and AMH was undetectable in plasma from castrated males. The number of follicles and wet weight of ovaries were much smaller in animals with a consistently low AFC compared with a high AFC (9 ± 1.33, 3.29 ± 0.34 vs. 28.27 ± 2.38, 3.98 ± 0.34; P < 0.01). Ovarian height and ovarian length (1.18 ± 0.31, 1.12 ± 0.40 vs. 1.54 ± 0.4, 1.14 ± 0.3) were similar (P > 0.05) between groups. Overall average circulating AMH concentrations were greater (P < 0.01) in animals with high AFC than in those with low AFC during follicular waves and was strongly correlated (r = 0.66) with AFC (r = 0.66, P < 0.01). Maximum values were 3.129 ng mL⁻¹ and minimum values were 0.37 ng mL⁻¹. In conclusion, the concentration of AMH was determined using a commercial rat-specific kit and can be used as a marker of ovarian reserve in alpacas.