Effect of management system and season on semen freezability in Jakhrana bucks

Evaluation of lipidomic change in goat sperm after cryopreservation

The current study aimed to detect the relationship between the spermatozoa cryotolerance and the post-thawed sperm lipidome. Ejaculates from 20 goats, and performed a uniform frozen-thawed procedure in this study. According to the total motility of thawed sperm of goats, semen samples were classified into HF group (High Freezers, n = 8) with >60% total motility and LF group (Low Freezers, n = 8) with < 45% total motility. The lipidomic analysis based on UHPLC-MS/MS was utilized to investigate the relationship between sperm cryotolerance and their lipid metabolites expression. The results showed that the cryotolerance of sperm from different individual goats were in great variation. The total motility of post-thawed sperm in HF group (60.93 ± 2.43%) is significantly higher than that in LF group (34.04 ± 3.41%, P < 0.01). And the post-thawed sperm in HF group exhibited significantly higher plasma membrane (59.06 ± 2.34%) and acrosome integrity (62.93 ± 1.15%) than that in LF group (34.06 ± 4.85%, 44.92 ± 2.19% respectively, P < 0.01). The total of 29 lipid subclasses and 1,133 lipid molecules in the post-thawed goat sperm were identified by lipidomics analysis. The lipid content of thawed sperm in HF group was higher than that in LF group, the lipid profile in HF group was significantly separated from LF group, which indicated that the difference in lipid composition and lipid metabolism mode of sperm between the two groups was existed, especially the expression of phosphatidylcholine and triglyceride molecules. In conclusion, the cryotolerance of sperm from different individual goats were in great variation. Sperm with high cryotolerance may be able to uptake more lipids during cryopreservation. The increase in phosphatidylcholine and triglyceride content of thawed. Sperm may relate to more active lipid anabolic processes.

In vitro supplementation of testosterone or prolactin affects spermatozoa freezability in small ruminants

In small ruminants, testosterone and prolactin plasma concentrations show circannual fluctuations as an adaptation mechanism to their seasonal breeding behavior. Sperm resistance to the freezing-thawing process shows seasonal fluctuation throughout the year, with lower sperm freezability at the beginning of the breeding season when prolactin and testosterone levels reach their maximum concentration. Nevertheless, whether these hormones directly affect post-thaw sperm quality parameters is still unclear. The objective was to study the effect of testosterone or prolactin added in vitro on sperm freezability in domestic ram (Ovis aries) and buck (Capra hircus). Sperm samples were incubated for 1 h with a range of testosterone (0, 2, 4, or 6 ng/mL; Exp. 1) or prolactin (0, 20, 100, 200, or 400 ng/mL; Exp. 2) concentrations. Samples were cryopreserved by slow freezing in straws at 0 h and after 1 h incubation. Sperm viability, acrosome integrity, motility, and kinetic parameters were assessed at 0 and 1 h in fresh and frozen-thawed samples. Results showed no hormone effect in fresh sperm, whereas these hormones affected post-thaw sperm parameters. In Exp. 1, in vitro incubation with testosterone decreased the post-thaw acrosome integrity of ram sperm (from 68.1 ± 6.3% to 49.6 ± 3.9%; P < 0.05). In Exp. 2, in vitro incubation with prolactin decreased the post-thaw acrosome integrity of ram (from 78.2 ± 3.4% to 66.3 ± 3.5%; P < 0.05) and buck sperm (from 81.7 ± 2.5% to 67.6 ± 3.5%; P < 0.05). Moreover, prolactin increased the post-thaw amplitude of lateral head displacement in ram sperm (from 3.3 ± 0.1 μm to 3.8 ± 0.2 μm; P < 0.05). In conclusion, either testosterone or prolactin added in vitro decreased the post-thaw acrosome integrity of ram and buck sperm. This suggests a destabilization process that could be decreasing sperm freezability when physiological levels of these hormones are high in vivo.

Effects of season and artificial photoperiod on semen and seminal plasma characteristics in bucks of two goat breeds maintained in a semen collection center

Aim:

This study quantified the effects of season and photoperiodic treatment on semen and seminal plasma (SP) characteristics in 12 bucks of two Spanish goat breeds (Murciano-Granadina, and Payoya) for the past 1 year.

Materials and Methods:

A total of 6 bucks (three of each breed) were exposed to the natural day length and the other six males (three of each breed) were exposed to alternating conditions of 2 months of long days (16 h light) and 2 months of short days (8 h light). Weekly concentrations of glutamic oxaloacetic transaminase/aspartate aminotransferase (GOT/AST), lactate dehydrogenase (LDH), potassium, testosterone, and protein in SP were measured. Reaction time and scrotal circumference were recorded, and plasma testosterone concentrations were measured before semen collection.

Results:

Sperm volume, LDH, and potassium concentration in SP, and reaction time did not differ significantly between breeds, seasons, and photoperiodic treatment. Sperm concentrations were higher (p<0.001) in spring and summer than they were in autumn and winter. Mean percentage of positive hypo-osmotic swelling test sperm was the highest in summer and under the artificial photoperiod (p<0.01). GOT/AST concentrations differed (p<0.01) between breeds and seasons. Breed, season, and photoperiod had significant (p<0.001) effects on protein and testosterone levels in SP. Plasma testosterone concentrations were highest in summer (p<0.001), and differed significantly (p<0.01) between breeds. Scrotal perimeter differed significantly (p<0.001) between breeds and photoperiod.

Conclusion:

Recognition of those seasonal and breed-specific differences in the performance of bucks should help to improve the management of individual semen samples for use in artificial insemination programs.