Semen characteristics and refrigeration in free-ranging giant anteaters (Myrmecophaga tridactyla)

Abstract

The giant anteater (Myrmecophaga tridactyla) is considered vulnerable to extinction. Scientific data on the reproductive parameters of this species are scarce. Semen from eight free-ranging giant anteaters was collected to establish its characteristics and the effects of cooling and storage at 5 °C after dilution with the BotuCrio extender without cryoprotectant. The ejaculate presented two distinct sequential fractions, including a whitish fraction, which was milky and rich in sperm cells, and a gel fraction, which was colorless, viscous, and azoospermic. The mean ± standard error of the mean values of the seminal characteristics were as follows: volume of the first fraction, 0.75 ± 0.1 mL; motility, 75 ± 2.9%; vigor, 3.2 ± 0.3; sperm motility index, 68.8 ± 4.3; concentration, 108.5 ± 13.4 × 10(6)/mL; plasma membrane integrity index, 71 ± 4.0%; spermatic defects detected using modified Karras staining, 35.5 ± 3.3%; and spermatic alterations identified by differential interference contrast microscopy, 48.3 ± 6.8%. During refrigeration, the semen presented decreasing motility from 0 to 18 hours, sperm motility index decreased from 0 to 24 hours, and vigor did not change in the first 6 hours and then decreased to 18 hours.