Nicht invasives Monitoring der Ovarfunktion bei Alpakas und Lamas

Zusammenfassung

Gegenstand und Ziel

Die Festlegung eines geeigneten Deckzeitzeitpunkts ist bei Neuweltkamelen (NWK) schwierig, da empfängnisbereite Stuten keine Brunstsymptome oder Verhaltensänderungen zeigen. Daher wurde die Anwendbarkeit der Messung von Sexualsteroiden in der Milch und der Vaginalzytologie als nicht invasive Methode zur Erfassung der Ovaraktivität untersucht.

Material und Methoden

Die Probenentnahmen erfolgten von insgesamt 10 Alpakas (A) und 9 Lamas (L) über einen Zeitraum von 4 Wochen nach der Geburt. Die Konzentrationen von Progesteron (P4), Estradiol-17β (E2) und Gesamtöstrogenen (GOE) in Blut und Milch wurden mittels Radioimmunoassays nach Probenextraktion gemessen. Die Anfertigung und Auswertung der Vaginalabstriche erfolgten nach dem beim Hund routinemäßig angewandten Verfahren.

Ergebnisse

Bei A und L waren die Östrogenkonzentrationen in der Milch im Vergleich zum Blut signifikant niedriger (E2 im Blut: A: 11,1±2,9 pg/ml, L: 14,6±5,0 pg/ml; E2 in der Milch: A: 6,2±3,1 pg/ml, L: 7,9±5,8 pg/ml; GOE im Blut: A: 120,2±26,9 pg/ml, L: 143,7±45 pg/ml; GOE in der Milch: A: 57,1±16,1, L: 75,9±34,6 pg/ml), während die Unterschiede zwischen den beiden Spezies nicht signifikant waren. Die Korrelationen zwischen den Steroidkonzentrationen in Blut und Milch waren bei L, nicht jedoch bei A, statistisch signifikant. Während sich bezüglich Korrelationen zwischen Östrogenkonzentrationen und vaginalzytologischen Parametern bei L mehrere statistische Signifikanzen mit p-Werten teilweise <0,01 ergaben, war bei A nur GOE im Blut negativ mit dem Anteil der Basal-/Parabasalzellen korreliert.

Schlussfolgerungen und klinische Relevanz

Die P4-Messung in der Milch erlaubt bei NWK mit großer Zuverlässigkeit die Erfassung von Lutealphasen. Trotz statistischer Signifikanz waren auch bei L die Korrelationen zwischen den Östrogenkonzentrationen in Blut und Milch zu schwach, um auf der Basis von Östrogenkonzentrationen in der Milch auf der Ebene des Einzeltieres die Blutkonzentrationen mit akzeptabler Genauigkeit abzuschätzen. Die Vaginalzytologie könnte bei L grundsätzlich zur Erkennung der Reifephase von Follikelwellen geeignet sein. Vor einer routinemäßigen Anwendung müssten jedoch Verbesserungen der Methodik und eine weitergehende Validierung vorgenommen werden.

Abstract

Objective and Aim

In South American Camelids (SAC), determining a suitable time point for mating poses challenges as females ready for conception do not show estrus signs or behavioral changes. Therefore, the applicability of measuring sex steroids in milk and vaginal cytology as non-invasive methods for monitoring ovarian activity was investigated.

Material and Methods

Samples were collected from a total of 10 alpacas (A) and 9 llamas (L) over a period of 4 weeks following parturition. The concentrations of progesterone (P4), estradiol-17β (E2) and total estrogens (GOE) in blood and milk were measured using radioimmunoassays after sample extraction. Vaginal swabs were prepared and evaluated according to the procedure routinely used in dogs.

Results

In A and L, the estrogen concentrations in milk were significantly lower than those in blood (E2 in blood: A: 11.1±2.9 pg/ml, L: 14.6±5.0 pg/ml; E2 in milk: A: 6.2±3.1 pg/ml, L: 7.9±5.8 pg/ml; GOE in blood: A: 120. 2±26.9 pg/ml, L: 143.7±45 pg/ml; GOE in milk: A: 57.1±16.1, L: 75.9±34.6 pg/ml), while the differences between the two species were not significant. The correlations between steroid concentrations in blood and milk were statistically significant in L, but not in A. While in L, correlations between estrogen concentrations and vaginal cytological parameters showed several statistical significances with p-values partly <0.01, in A only GOE in the blood was negatively correlated with the proportion of basal-/parabasal cells.

Conclusions and Clinical Relevance

P4 measurement in milk allows the detection of luteal phases in SAC with high reliability. Despite statistical significance, the correlations between estrogen concentrations in blood and milk were also too weak in L to estimate blood concentrations with acceptable accuracy based on estrogen concentrations in milk at the level of the individual animal. Vaginal cytology could in principle be suitable for the identification of the maturation phase of follicular waves in L. However, improvements of the methodology and further validation are warranted before its routine use.

Schlüsselwörter

Neuweltkamel - Estradiol - Progesteron - Gesamtöstrogene - Follikelwellen

Keywords

South American camelid - estradiol - progesterone - total estrogens - follicular waves

Publikationsverlauf

Eingereicht: 25. November 2024

Angenommen: 13. Mai 2025

Artikel online veröffentlicht:
02. September 2025

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