Sperm morphology is better in the second ejaculate than in the first in domestic cats electroejaculated twice during the same period of anesthesia

Several species produce ejaculates of inferior quality after a period of sexual abstinence, but the frequency of semen collection has thus far not been shown to affect sperm morphology in felids. The aim of this study was to determine whether sperm morphology and motility would differ between 2 ejaculates collected from the same cat within a short interval. Fifteen male domestic cats were anesthetized and then electroejaculated twice, with a 5- to 10-min interval between treatments. A standardized electroejaculation regimen was used with 80 stimuli, from 2 to 5 V, for each ejaculate. The first ejaculates contained significantly higher (P < 0.05) proportions of distal droplets, coiled tails and immotile spermatozoa than the second ejaculates, which contained significantly higher proportions of morphologically normal spermatozoa (40.9 vs 54.6%) but a lower sperm count (39.0 x 10(6) vs 5.2 x 10(6)). The higher proportions of defective spermatozoa and the lower motility in the first ejaculate than in the second were probably due to the aging of spermatozoa in the epididymis. These results show that the second ejaculate collected within a short interval has better sperm morphology and motility than the first and that this should be considered when evaluating semen quality in the domestic cat and when collecting cat semen to be used for artificial insemination or to be frozen for storage. (C) 1997 by Elsevier Science Inc.