Effect of time and depth of insemination on fertility of Bharat Merino sheep inseminated trans-cervical with frozen-thawed semen

Carboxymethyl cellulose and glycerol act synergistically as cryoprotectant during cryopreservation of ram semen

Wider implementation of AI in sheep in the field condition has not been possible till date due to very poor conception rate after cervical insemination with cryopreserved semen. Poor cervical penetrability in ewe and diminished sperm functions in cryopreserved semen are considered responsible for it. In the present study, effect of carboxymethyl cellulose (CMC) on post-thaw qualities of ram semen was investigated. Ejaculates from eight adult Malpura rams were pooled and diluted (800 × 10⁶ sperm mL^-1) with TES-Tris-fructose-egg yolk extender having either 5 or 6% glycerol and supplemented with 0, 0.25, 0.5, 0.75 and 1.0% (w/v) CMC and packaged into 0.25 mL French mini straws. The straws were progressively cooled to 5 °C inside a cold cabinet (5 °C) and then equilibrated for 22 h inside a refrigerator (2-5 °C). Straws were frozen at -25 °C min^-1 up to -125 °C using a programmable cell freezer (Planer Biomed R-204, UK) and finally plunged into liquid nitrogen. The post-thaw progressive motility was higher (P < 0.05) in 0.75% CMC-treated group compared to control. Overall, both pre-freeze and post-thaw sperm kinetics was comparable between CMC-treated and control groups. The post-thaw sperm viability, acrosomal integrity and sperm with high mitochondrial membrane potential (hMMP) were relatively higher while sperm with high membrane cholesterol was significantly (P < 0.05) higher in presence of 0.25% CMC compared to the control. Both sperm having hMMP and non-capacitated sperm were significantly (P < 0.05) higher in presence of 5% glycerol than 6% glycerol. Similarly, functional membrane integrity (FMI) was higher in presence of 5% glycerol than 6% glycerol when CMC was added at 0.5% to extender. In conclusion, both 0.25% CMC and 5% glycerol resulted in improvement in several post-thaw sperm functions in cryopreserved ram semen. Thus CMC demonstrated cryoprotective effect on ram sperm in a synergistic manner with glycerol.

Local α1-adrenergic blockers: An alternative for sheep cervix dilation?

To facilitate transcervical artificial insemination in sheep, the effects of local treatment with α1-adrenergic receptor antagonists on cervix dilation and hemodynamics were evaluated. Ewes (n = 7) were subjected to oestrous synchronisation every 40 days and assigned to treatments in a Latin square experimental design (seven animals × seven periods) with a factorial treatment arrangement (A × B), Factors A (prazosin or tamsulosin) and B (1, 2, or 4 mg/animal). Ewes of the six treatment groups (P1, P2, P4, T1, T2, and T4) were administered α1-adrenergic receptor antagonists while those of the control group (CG) were administered only α1-adrenergic antagonist carrier agent. Distance that the transcervical catheter penetrated without cervical resistance, mean arterial pressure, and uterine artery dopplerfluxometry were evaluated before and after 30 min, 1, 2, 4, 8, and 10 h of treatment. Catheter penetration distance was greater in ewes of the T4 and P4 groups (P < 0.01), with there being a positive correlation between dose and distance (r = 0.243). The penetration distance was similar (P = 0.84) for treated groups, with the greatest penetration occurring 2, 4, and 6 h after treatment (P < 0.01). The passage into the uterine lumen was greater (P = 0.013) in ewes of the P4 (17.9 %) and T4 (19.6 %) groups. There were no effects on blood pressure or uterine blood flow (P> 0.05). These preliminary results indicate there are benefits of treatment with 4 mg/animal of tamsulosin or prazosin in catheter passage through the sheep cervix 2-6 h after administration without hemodynamic effects.

Effect of cervical insemination with frozen semen on fertility of Indian goat breed

Artificial Insemination (AI) has great potential to multiply superior quality of goat with faster rate in spite of lower conception rate. This technique will spread elite genetic material throughout a population and is also important for breed conservation and has paved the way for other reproductive biotechnologies. Ejaculates from bucks aged between 2–4 years old from Jamunapari, Barbari, Sirohi and Jakhrana were collected using artificial vagina, twice a week. Immediately after collection, the volume, colour, consistency, and mass motility of ejaculate were assessed and were extended with Tris -Egg yolk- Fructose diluent having 10% (v/v) egg yolk and glycerol 6% (v/v). Sperm concentrations were adjusted to 1×108/ml and diluted semen was equilibrated at 5°C for 4 h before being frozen. The post thaw motility in Jamunapari and Barbari was significantly higher then Jakhrana and Sirohi. In two major breeding seasons (May–June and October–November), 181 goats of different breeds (Barbari, Jakhrana, Jamunapari and Sirohi) including 35 goats in villages were intra-cervical inseminated with frozen semen in natural estrous condition. The kidding percentage in Barbari, Jamunapari, Jakhrana and Sirohi were 53.12±2.40%, 34.61±1.96%, 26.53±2.12% and 28.57±2.32% respectively. Overall, a success rate of 37.57% was recorded on the basis of actual kidding rate irrespective of goat breed maintained at this institute under semi-intensive management system. The best post thaw quality of buck semen and comparative deeper cervical insemination in Barbari and Jamunapri breeds results in higher conception and kidding percent compared to other breeds (Sirohi and Jakhrana).

Pre-freezing equilibration for 22 h improves post-thaw sperm functions in cryopreserved ram semen by reducing cholesterol efflux

Failure of cervical insemination with cryopreserved semen is hindering implementation of AI in sheep in field condition. Here the effect of equilibration time and catalase on post-thaw qualities of ram semen was investigated. Pooled semen was diluted (800 × 10⁶ sperm mL^-1) with a TES-Tris-fructose extender with 6% glycerol, 15% egg yolk and supplemented with 0, 50, 100 and 200 U mL^-1 catalase and packaged into 0.25 mL straws. In experiment 1, straws were equilibrated at 5 °C either for 3 h in a cold cabinet (E3) or for 10 (E10) and 22 h (E22) inside a refrigerator. In experiment 2, all straws were equilibrated for 22 h inside refrigerator. Straws were frozen at -25 °C min^-1 up to -125 °C using a cell freezer and finally plunged into liquid nitrogen. The post-thaw total and rapid motility were higher (P < 0.05) in E22 compared to E3 and E10. Sperm kinetics was comparable between E3 and E22, but lower in E10. Similarly, acrosome integrity, functional membrane integrity, percent high cholesterol (mCHO) and live-high mitochondrial membrane potential (MMP) were higher (P < 0.05) while live-high intracellular calcium and acrosome-reacted sperm were lower in E22 compared to E3 and E10. The percent rapid motile, high mCHO and live-high MMP were significantly (P < 0.05) lower in catalase-treated samples compared to the control, while the membrane integrity was comparable within the groups. In conclusion, pre-freezing equilibration for 22 h compared to 3 or 10 h resulted in higher post-thaw sperm functions while catalase had negative impact on cryopreservation of ram semen.

Technical recommendations for artificial insemination in sheep

Artificial insemination (AI) was the first important biotechnology applied to improve the genetics of farm animals. It allows the rapid and massive diffusion of desirable characteristics of males with high productive potential. We describe the different types of estrus induction and synchronization techniques and the use of the AI with fresh, chilled or frozen semen. Through the adequacy of the protocols of estrus synchronization and AI to the different production systems, the efficient use of reproductive techniques is possible, reaching acceptable pregnancy rates. Summary of reproductive results obtained using cervical and laparoscopic AI are presented.

Status of beta defensin-1 in Indian goat breeds

The present study was carried out to know the status of Beta Defensin-1 in goat semen before and after cryopreservation with beta defensin-1 supplemented semen diluent and in blood of different breeds of goat (Barbari, Jamunapari and Jakhrana). Goat semen (N-10) from each breed was collected by artificial vagina method. Immediately after collection, the volume, colour, consistency, and mass motility of ejaculate were assessed and were extended with Tris-Egg yolk-Fructose diluent having 10% (v/v) egg yolk and glycerol 6% (v/v). Samples were divided for estimation of beta defensin–1 and rest parts were cryopreserved with semen diluent having beta defensin-1 @ 10 ng/mL. Blood samples (N-30) were also collected from the same animal after semen collection. The samples were stored at –20°C until assayed. Plasma membrane of sperm was broken by freeze thaw followed by ultracentrifugation (20,000 × g for 5 min) at room temperature before ELISA test. The samples were diluted with Phosphate buffer (1:2) before analysis. The samples were analyzed using goat specific beta defensin–1 commercial kit (EO6D0419) as per the manufacturer’s instruction. The result showed that with supplementation of beta defensin-1 in goat semen, diluent maintains the concentration of beta defensin-1 even after cryopreservation. There was significant decrease (P<0.05) in beta defensin-1 concentration in sample which had no supplement in semen diluent after cryopreservation. The supplementation of beta defensin-1 in goat semen diluent improved the post-thaw immune modulatory properties of semen.

Administration time of misoprostol affects fertility rate in artificially inseminated Kivircik ewes with frozen-thawed ram semen

The aim of this study was to determine the effects of the administration time of misoprostol (11 h (Miso11) and 6 h (Miso6) before artificial insemination) on fertility rates in Kivircik ewes (control: n = 41, Miso11: n = 32 and Miso6: n = 33) during breeding season. Artificial insemination (AI) was performed 48 h after sponge removal using frozen-thawed semen (150 million sperm per dose in 0.25 ml straws). Estrus synchronization parameters (onset and duration) and lambing rate were evaluated. No significant difference was observed among groups for the estrus onset and duration hours (P > 0.05). The lambing rates in the control, Miso11 and Miso6 groups were 39.0, 62.5 and 54.5%, respectively. There were significant differences among the control, Miso11 and Miso6 groups according to lambing rates (P < 0.05). In conclusion, misoprostol treatment significantly improved fertility in ewes when using frozen-thawed semen in AI. Administration of misoprostol 11 h before AI resulted in a higher lambing rate than that at 6 h before AI; therefore, treatment of misoprostol 11 h before AI can effectively be used.

Effect of thawing methods on frozen semen quality of yak (Poephagus grunniens L.) bulls

Aim:

To evaluate different thawing temperatures and duration on the post-thaw semen quality of Indian yaks bulls.

Materials and Methods:

Semen ejaculates from four different yak bulls were collected using artificial vagina method and extended with tris extender containing 6.4% glycerol at 35°C, cooled gradually from 35°C to 5°C at 1°C/3 min and equilibrated at 4-5°C for 4 h and frozen in French mini straws using a programmable bio-freezer and finally stored in liquid nitrogen. Thawing of frozen semen straws was carried out using three methods i.e., 35°C for 60 s (thawing method I), 37°C for 30 s (thawing method II) and 75°C for 9 s (thawing method III). The post-thaw semen quality parameters assessed were sperm motility, percent live sperm, hypo-osmotic swelling test (HOST)-reacted sperm, acrosomal changes, and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in the extracellular media.

Results:

The percent sperm motility, total incidence of acrosomal changes, and extracellular release of AST varied significantly (p<0.01) between thawing methods but live sperm and HOST-reacted sperm did not vary significantly between thawing methods. The percent sperm motility of frozen yak semen for thawing method III was significantly (p<0.05) higher than that for thawing methods I and II, the difference between thawing methods I and II being non-significant. The critical difference test revealed that the total incidence of acrosomal changes and extracellular release of AST were significantly (p<0.05) lower when thawing was done using methods I and II than in method III.

Conclusion:

On the basis of the present experiment, we can conclude that barring the post-thaw sperm motility, thawing of frozen yak semen in water either at 35°C for 60 s or 37°C for 30 s gives better post-thaw semen quality than at 75°C for 09 s.