Alkaline phosphatase as an indicator of true ejaculation in the rhinoceros

• Published in: Theriogenology Vol. 74; no. 9; pp. 1701 - 1706
• Main Authors: Roth, T.L., Stoops, M.A., Robeck, T.R., Ball, R.L., Wolfe, B.A., Finnegan, M.V., O'Brien, J.K.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-12-2010; [Oxford]: Butterworth-Heinemann; [New York]: Elsevier Science
• Subjects: African black rhino; African white rhino; alkaline phosphatase; Alkaline Phosphatase - analysis; Animals; assisted reproductive technologies; biomarkers; Ceratotherium; Ceratotherium simum; Dicerorhinus; Dicerorhinus sumatrensis; Diceros bicornis; Ejaculation; Electroejaculation; epididymis; Hydrogen-Ion Concentration; Indian rhino; Male; males; Osmolar Concentration; osmolarity; Perissodactyla - metabolism; Rhinoceros; Rhinoceros unicornis; Semen; Semen - enzymology; Sperm Count - veterinary; spermatozoa; Sumatran rhino; testes; validity; wild animals; zoo animals; Electroejaculation; Indian rhino; Semen; Sumatran rhino; African white rhino; African black rhino
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2010.05.021

The objective was to determine if seminal alkaline phosphatase (ALP) can serve as an indicator of true ejaculation in the rhinoceros. Concentrations of ALP activity were determined in seminal fractions collected from African black rhinos (
Diceros bicornis), an African white rhino (
Ceratotherium simum), and an Indian rhino (
Rhinoceros unicornis) during electroejaculation. In addition, seminal fractions collected during penile massage of a Sumatran rhino (
Dicerorhinus sumatrensis) were assessed. Correlations between ALP activity and sperm concentration, fraction pH, and fraction osmolality were evaluated in the Indian rhino and black rhino. Concentrations of ALP activity in rhino ejaculate fractions ranged from < 5 to 11,780 U/L and were positively correlated (P < 0.05) with sperm concentration for both Indian rhino (r = 0.995) and black rhino (r = 0.697), but did not exhibit a strong correlation with either pH or osmolality (P > 0.05). Data were insufficient for establishing meaningful correlation coefficients in the Sumatran rhino and white rhino, but preliminary results were in accordance with findings in the Indian rhino and black rhino. We concluded that ALP was present in rhinoceros semen, likely originated from the epididymides and/or testes, and could serve as a useful tool for assessing the production of ejaculatory versus pre-ejaculatory fluid in the rhinoceros.