Ejaculation training, seminal alkaline phosphatase and semen preservation through cooling in a milk-based extender in domestic cats

Abstract

The purpose of this report is to describe (1) the training of domestic cats in ejaculation into an artificial vagina (AV), (2) alkaline phosphatase (AP) concentrations in whole ejaculates, and (3) the in vitro effect of a skimmed-milk plus egg yolk (SM-Y) extender on feline spermatozoa incubated at 4ºC. Five post-pubertal cats were trained to ejaculate into an AV three times a week for 20 mins in the presence of a teaser queen. Fifty AV-obtained ejaculates were macro- and microscopically assessed, and the AP therein measured by optimized colorimetry. Eighty AV-obtained ejaculates were pooled, diluted in SM-Y extender [80% (v/v) skimmed milk, 20% (v/v) egg yolk, and antibiotics], stored at 4°C and evaluated daily for 6 days. All the animals could be trained to ejaculate, although the interval up to the first AV ejaculation varied from 1.5 to 5.5 months (mean 3.9 months). The final performance at collection ranged from excellent to poor and was inversely related to the training period required in all cases. The mean AP concentration in whole ejaculates was 20,645.6 ± 4405U/l, which was not correlated with the concentration of spermatozoa. Most seminal parameters [(%); total (77 ± 2.3) and progressive (62.7 ± 3.4) motility, live sperm (91.8 ± 1.2), intact plasmalemma (83.5 ± 2.6), normal acrosomes (83.5 ± 2.6), pH (6.6 ± 0.0) and osmolarity (mOsm/l; 321 ± 5.2)], though decreasing during storage in the cold, remained within values compatible with in vivo fertilization for 2 days.