Spermiation of paddlefish (Polyodon spathula, Acipenseriformes) stimulated with injection of LHRH analogue and carp pituitary powder

¹ University of South Bohemia, Research Institute of Fish Culture and Hydrobiology, 38925 Vodnany, Czech Republic
² Aquaculture Research Center, Kentucky State University, Frankfort, KY 40601, USA
³ Zoology Department, University of Oklahoma, Norman, OK 73019, USA
⁴ Centre national de la recherche scientifique, URA 671, station marine, 06230 Villefranche-sur-Mer, France

Received: 13 December 1999
Accepted: 4 July 2000

Abstract

The potential of carp pituitary powder (CPP) at one dose, or the luteinizing hormone-releasing hormone (LH-RH) analogue, des–Gly¹⁰,(D–Ala⁶)–LH-RH–ethylamide, at three different doses to stimulate spermiation in paddlefish (Polyodon spathula) was tested. Single injections of the LH-RH analogue at 0.2, 0.1, or 0.05 mg·kg^–1 increased the number of spermatozoa per kilogram of body weight (kg^–1 b.w.) by 4.7, 3.4, and 3.4 times respectively compared to control, but the number of spermatozoa per kilogram of body weight decreased with CPP (4 mg·kg^–1) by 1.7 times compared to the control. The LH-RH analogue prolonged active spermiation, with numbers of spermatozoa ranging from 7.69 to 1.19 × 10⁹ kg^–1 b.w. up to 96 h after treatment. Analysis of variance showed significant influence of experimental groups on volume of sperm per male and per kilogram of body weight, and the total number of spermatozoa per kilogram of body weight, but insignificant influence on the total number of spermatozoa per male. The percentage of motile spermatozoa was not different between experimental groups for sperm collection at different times after injection. A very high positive correlation (r = 0.93) was obtained between sperm concentration and sperm transmittance measured with a spectrophotometer. This relationship was described with the following linear regression: sperm concentration (× 10⁹ mL^–1) = 1.3244 X^–0.9969, where X is the percentage of sperm transmittance.