Abstract
OBJECTIVE: Anti-Müllerian hormone (AMH) has become an important hormonal parameter for the detection of gonadal tissue and for the diagnosis of gonadal functions and pathologies. To our knowledge, there is currently no homologous test for AMH measurements in South American camelids (SACs). Therefore, the objective of the present study was to determine serum AMH concentrations in postpubertal male alpacas and, for the first time, in llamas, using the Elecsys AMH assay kit that has not previously been tested in these species. To obtain indications of the specificity of this method in SAC, measurements were carried out in male gelding in which concentrations below the detection limit were to be expected. METHODS: In this context, 37 blood samples collected by jugular venipuncture from 21 alpacas and 16 llamas were used. The obtained blood was centrifuged at 3000 g for 20 min, and the serum was stored in Eppendorf tubes at -20°C until AMH concentrations were measurement. The measurement of AMH levels was conducted in a commercial diagnostic laboratory (Laboklin, Bad Kissingen, Germany) using the electrochemiluminescence immunoassay kit Elecsys AMH run on the fully automated Cobas e 601 analyser (Roche Diagnostics Deutschland GmbH, Mannheim). The AMH test had a minimum detection limit of 0.01 ng/mL and a maximum detection limit of 23 ng/mL. The intra-assay coefficient of variation is between 2.7% and 3.3%. RESULTS: Blood serum AMH levels ranged between 4.10 and 22 ng/mL (median: 9.80 ng/mL) and 1.79 and 10.05 ng/mL (median: 4.00) in intact alpacas (age: 6.30 ± 2.71 years; n = 10) and llamas (age: 5.50 ± 4.34; n = 8), respectively, and were significantly different between samples obtained from the two species (p < 0.05). Correlation analyses regarding an age dependence of AMH concentrations yielded negative correlation coefficients for both species but non-significant p values (alpaca: r = -0.165, p = 0.649; llama: r = -0.547, p = 0.160). In alpaca (n = 11) and llama geldings (n = 8), blood serum AMH levels were below 0.01 ng/mL (p < 0.001). These results prove that the antibodies used in the Elecsys AMH assay significantly and specifically cross-react with SAC AMH. CONCLUSIONS: In gelding llamas and alpacas, AMH concentrations were below the limit of detection (<0.01 ng/mL), which was significantly lower compared to intact animals (p < 0.001). The Elecsys AMH assay is therefore considered a suitable method for detecting gonadal tissue in SAC.