Factors influencing boar sperm cryosurvival1

Abstract

Optimal sperm cryopreservation is a prerequisite for the sustainable commercial application of frozen-thawed boar semen for AI. Three experiments were performed to identify factors influencing variability of postthaw sperm survival among 464 boar ejaculates. Sperm-rich ejaculate fractions were cryopre-served using a standard freezing-thawing procedure for 0.5-mL plastic straws and computer-controlled freezing equipment. Postthaw sperm motility (assessed with a computer-assisted semen analysis system) and viability (simultaneously probed by flow cytometry analysis after triple-fluorescent stain), evaluated 30 and 150 min postthaw, were used to estimate the success of cryopreservation. In the first experiment, 168 unselected ejaculates (1 ejaculate/boar), from boars of 6 breeds with a wide age range (8 to 48 mo), were cryopreserved over a 12-mo period to evaluate the predictive value of boar (breed and age), semen collection, transport variables (season of ejaculate collection, interval between collections, and ejaculate temperature exposure), initial semen traits, and sperm quality before freezing on sperm survival after freezing-thawing. In Exp. 2, 4 ejaculates from each of 29 boars, preselected according to their initial semen traits and sperm quality before freezing, were collected and frozen over a 6-mo period to evaluate the influence of interboar and intraboar ejaculate variability in the survival of sperm after cryopreservation. In Exp. 3, 12 ejaculates preselected as for Exp. 2, from each of 15 boars with known good sperm cryosurvival, were collected and frozen over a 12-mo period to estimate the sustainability of sperm cryosurvival between ejaculates over time. Boar and semen collection and transport variables were not predictive of sperm cryosurvival among ejaculates. Initial semen traits and sperm quality variables observed before freezing explained 23.2 and 10.9%, respectively, of the variation in postthaw sperm motility and viability. However, more that 70% of total variance observed in postthaw sperm quality variables among ejaculates was explained by boar. This indicates that boar is the most important (P < 0.001) factor explaining the variability among ejaculates in sperm cryosurvival, with most (14 of the 15 boars in Exp. 3) showing consistent (P > 0.05) sperm cryosurvival over time.

Boar variability affects sperm metabolism activity in liquid stored semen at 5°C

“…Investigations conducted by Roca et al (2006a) indicated that individual differences are the main factor explaining differences in the viability of cryopreserved spermatozoa. Thurston et al (2002) and Fraser et al (2008) showed that differences in the quality of cryopreserved boar sperm are determined genetically.…”

Effects of storage in different semen extenders on the pre-freezing and post-thawing quality of boar spermatozoa

“…Numerous studies have demonstrated that liquid storage or cryopreservation of boar semen induces marked changes in the structural and functional integrity of the sperm membranes (Roca et al 2006, Gączarzewicz et al 2010. During the cryopreservation procedure, damage to the sperm mitochondria occurs, which in turn leads to the disruption of the oxidative phosphorylation process, and a reduction in post-thaw sperm motility (Johnson et al 2000, Peñ a et al 2011, Guthrie and Welch 2006, 2012.…”

Identification of ultrastructural and functional damages in sperm from six-banded armadillos (Euphractus sexcinctus) due to cryopreservation

“…For domestic animals as equines (Thurston et al 2002) and swines (Roca et al 2006), whose studies on the evaluation of post-thawing sperm viability are intensely developed, one of the major limitations for the use of frozen semen is the individual variability to sperm freezeability. Similarly, a variable resistance to cryoinjuries was found among different armadillos used in present study.…”