Semen from the first 15mL of the ejaculate (P1) obtained from two boars (30mL) was diluted in glycine-egg yolk extender, cooled at 5°C in a special container and rediluted in standard doses of 3x109 mobile spermatozoa after 12h of storage. Semen was also stored up to 24h after redilution. The physical characteristics of the semen were evaluated at different storage periods (fresh, 0h, 12h, rediluted, 24h, and 36h). The reproductive performance of the boars and their fertility regarding the insemination of primiparous sows were also determined. Two treatments were used: T1-15B sows inseminated with semen originated from hyperconcentrated heterospermic doses (15x109 mobile spermatozoa per dose), rediluted after 12h of storage at 5°C for standard doses of 3x109 mobile spermatozoa per dose and stored at 5°C up to 24h after redilution (n=10); T2-3B sows inseminated with standard heterospermic doses (3x109 mobile spermatozoa per dose), stored at 5°C up to 36h after semen collection (n=10). There was no effect (P>0.05) of treatments on the spermatic motility, even though a pronounced decrease (P>0.05) of their values at 12h of storage was recorded. However, they remained higher than 70% until 36h. There was effect of treatments on spermatic vigour at 0h (P<0.05), when T1-15B vigour was higher. There was also effect of the storage period for both treatments with a progressive decrease throughout 36h of storage, although the differences were not always significant. Pregnancy rates (90%) and the number of total farrowed piglets (15, 11-T1-15B; 13, 44- T2-3B) did not differ (P>0.05) between the treatments. It was concluded that the semen hyperconcentration of 15 billion of mobile spermatozoa per dose, stored at 5°C for 12h, did not result in drawbacks considering the physical characteristics of the semen, maintaining the pregnancy rates and prolificacy of the inseminated sows.
swine; fractioned collection; cooling; transport