Eficiência reprodutiva de fêmeas suínas inseminadas com sêmen heterospérmico hiperconcentrado e rediluído após 12 horas de armazenamento a 5ºC no diluidor glicina-gema de ovo

Abstract

The hyperconcentration of heterospermic semen of boars containing 15 billion (experiment I) or 24 billion (experiment II) of mobile spermatozoa per 100mL dose was studied aiming to optimize the transport of cooled semen stored in special container to be used in artificial insemination of sows in commercial hog farms. For that purpose, semen from the first 15mL of the ejaculate (P1) obtained from two boars (30mL) was diluted in glycine-egg yolk diluter (Foote, 2002), cooled at 5ºC in a special container and rediluted in standard doses of 3 billion mobile spermatozoa after 12h of storage. Semen was also stored up to 24h after redilution. In both experiments, 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 in each experiment: E1T1-15B sows inseminated with semen originated from hyperconcentrated heterospermic doses (15x109 mobile spermatozoa per dose), rediluted after 12h of storage at 5ºC for standard doses of 3x109mobile spermatozoa per dose and stored at 5ºC up to 24h after redilution (n=10); E1T2-3B - sows inseminated with standard heterospermic doses (3x109 mobile spermatozoa per dose), stored at 5ºC up to 36h after semen collection (n=10); E2T1-24B - sows inseminated with semen originated from hyperconcentrated heterospermic doses (24x109 mobile spermatozoa per dose), rediluted after 12h of storage at 5ºC for standard doses of 3x109 mobile spermatozoa per dose and stored at 5ºC up to 24h after redilution (n=10); and E2T2-3B - sows inseminated with standard heterospermic doses (3x109 mobile spermatozoa per dose), stored at 5ºC up to 36h after collection (n=10). In experiment I, 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 the treatments on the spermatic vigor at 0h (p<0.05), when T1 vigor was higher. There was also effect of the storage period for both treatments, with a progressive decrease throughout the 36h of storage, although the differences were not always significant. Pregnancy rates (90%) and the number of total farrowed piglets (15.11 E1T1-15B and 13.44 E1T2-3B) did not differ (p>0.05) between the treatments of the experiment I. In experiment II, there was no effect of treatments (p>0.05) on the spermatic vigor and motility. However, there was a decrease of motility (p<0.05) since at 12h of storage and throughout the storage period from 12 to 36h. There was no effect of redilution up to 36h on the values of spermatic vigor in E2T1-24B, although the value at 36h was differed (p<0.05) of that recorded at 12h (previous to dilution). In E2T2-3B, the vigor was maintained from 12 to 36h of storage, and the values registered at 36h only differed (p<0.05) from those observed in fresh semen and when evaluated at 0h. A progressive decrease of vigor was also observed in this experiment, although the differences were not always significant. The pregnant rates (100 vs. 80%) and the total number of farrowed piglets (14.00 vs. 16.50), respectively for the treatments 1 and 2 of the experiment II, were similar (p>0.05). Then, it was concluded that the hyperconcentration of the semen to 15 or 24 billion of mobile spermatozoa per dose, stored at 5ºC for 12h, did not result in drawbacks considering the physical characteristics of the semen and the reproductive performance of the boars, maintaining the pregnancy rates and prolificity of the inseminated sows within commercially acceptable values.