14 Sublethal Hydrostatic Pressure Treatment Improves Fresh and Chilled Boar Semen Quality in Vitro and in Vivo

Abstract

Insemination of fresh boar semen is a widely used production tool in swine breeding and meat production. Although the success rates of routine insemination procedures are satisfactory, improvements are still needed to reduce production costs; moreover, the reduced litter size of gilts compared with sows still calls for further solutions. Sublethal high hydrostatic pressure (HHP), applied to fresh boar semen before cryopreservation, was reported to improve post-thaw motility and litter size. Proteomic studies revealed a treatment-related increase in different proteins that may contribute to increased fertility (Huang et al. 2008 Anim. Reprod. Sci., in press). Herein, we provide data showing how the same treatment influences the in vitro lifespan of semen stored at 15°C and fertility at routine fresh semen insemination. For in vitro evaluation, semen was collected from Seghers boars (n = 7), extended, cooled to room temperature, and then split into 2 groups. Semen in the treatment group was filled into sterile transfusion bags and treated with 300-bar pressure for 90 min at 25°C in a computer-controlled pressure device (Cryo-Innovation Ltd., Budapest, Hungary). After treatment, both groups were placed into a cooling thermostat set to 15°C. Total and progressive motility was assessed daily for 12 days by a computer-assisted semen analysis system. For in vivo evaluation, semen (boars, n = 14) was prepared, split, and treated as described above. Hungarian Large White × Hungarian Landrace sows (n = 103) were then inseminated with treated or nontreated semen. Inseminations were done in the routine production of 2 swine farms. For statistical analysis, a generalized linear mixed-effects model was used, with P < 0.05 regarded as significant. Results showed that the reduction of both total (TM) and progressive (PM) motility of the treated samples was significantly slower compared with control samples. On Day 5, the ratio of live (TM) to PM cells (control v. HHP treated) was as follows: TM, 55.4 v. 64.6%; PM, 36.6 v. 46.4%. On Day 11, the ratio of TM to PM cells was as follows: TM, 43 v. 53%; PM, 27 v. 31.4%. Mean pregnancy rates and litter weights were not different between the 2 groups (73 v. 74%; 16.34 v. 16.37 kg; HHP treated v. nontreated, respectively). However, the effect of treatment on the litter size was significant (12.4 v. 11.4; HHP treated v. nontreated). Moreover, there was a significant difference in treatment effects between the gilts and the sows: whereas treatment had no significant effect on the litter size of the sows (P = 0.47), the litter size of the gilts increased (P < 0.001), with a mean of 2.55 ± 0.83 (SE). This preliminary report shows that HHP-treated semen survived chilled storage better. The HHP treatment also increased the average live and total litter size achievable with fresh semen insemination, with litters not being different from the controls in weight, sex ratio, or stillbirths. The increased litter size was more evident in the case of the gilts. Further field trials are being conducted. This trial was supported by OMFB-00364/2007.

Effect of ethanol induced mild stress on post-thawed bull sperm quality

“…Our data revealed that the O-E9 group increased sperm viably and therefore can be applied successfully to increase the efficiency of freeze-thawing process in bull. This observation is in line with an earlier study in which an increased sperm survival after cryopreservation or prolonged in vitro storage has been achieved by hydrostatic pressure-induced stress tolerance in bull [43] and boar [44].…”

Stress for Stress Tolerance? A Fundamentally New Approach in Mammalian Embryology1

“…The treatment did not increase pregnancy or farrowing rates, but a significant increase of litter size was observed. A positive effect was also demonstrated by in vitro investigations, where the lifespan of routinely stored boar semen increased after HHP treatment [13]. Further experiments have demonstrated that HHP treatment considerably improved the cryotolerance of porcine semen [14,15].…”

“…Up till the date of the submission of this manuscript, 491 and 155 healthy piglets were born as a result of the insemination of HHP-treated fresh or cryopreserved spermatozoa, respectively [13,16]. Piglets were not different from the control in sex ratio, weight, stillbirth, and malformations.…”

Stress Preconditioning of Boar Spermatozoa: A New Approach to Enhance Semen Quality*

“…For in vitro evaluation, treated or not treated semen was kept in a cooling thermostat set to 16°C. Total and progressive motility measured at days 5 and 12 was significantly higher in the treated groups compared with control (Pribenszky et al. 2009).…”

“…However, the effect of treatment on the litter size was significant (12.4 vs 11.4; HP treated vs non‐treated). Moreover, there was a significant difference in treatment effects between the gilts and the sows, whereas treatment had no significant effect on the litter size of the sows (p = 0.47), the litter size of the gilts increased (p < 0.001), with a mean of 2.55 ± 0.83 (SE) (Pribenszky et al. 2009).…”