EFFECT OF COLLECTION RHYTHM ON SPERMATOZOA AND DROPLET CONCENTRATION OF RABBIT SEMEN

ABSTRACT: The aim of the paper was to analyse the effect of collection rhythms on spermatozoa and droplet concentration of rabbit semen. Thirty adult New Zealand White rabbit bucks were submitted to 3 collection rhythms: every day (D), every week (W), every 2 weeks (2W). The trial lasted 71 days and a total of 790 ejaculates were collected. Volume, concentration of spermatozoa, droplets and their dimensions were evaluated. Ejaculate volume and concentration of spermatozoa were the lowest (0.37 ± 0.08 mL and 48.9 ± 43.8x106 mL-1, respectively) when the samples were collected daily, whereas the ratio droplets/spermatozoa was the highest (6.4 ± 3.3). The output of spermatozoa per week was the highest with W rhythm (173.4 ± 105.3x106), followed by D (134.2 ± 75.1x106) and by 2W (79.5 ± 49.8x106) collection whereas the weekly output of droplets was the highest for D (810.2 ± 615.7x106). In the following order of collection the spermatozoa concentration was similar in W and 2W while D showed a sharp decline of values after few collections. Semen droplets with respect to spermatozoa showed a more stable trend showing that droplets are able to respond better to high soliciting. Bucks submitted to an intensive rhythm were able to increase about 9-fold (respecting to W) the secretion of droplets by prostate glands. As a result, the ratio droplet/spermatozoa showed the highest values in daily collected semen (6.4 ± 3.3). The repeatability of seminal traits showed that volume and spermatozoa concentration had the highest value followed by droplets, and ratio droplets/spermatozoa. In conclusion, it is possible to affirm that the collection rhythm, besides influencing the concentration of spermatozoa, also affects the rate of droplet production. A collection rhythm every 2 weeks was detrimental to both the spermatozoa and droplet output. Key words: rabbit, semen, spermatozoa, seminal droplet