The effect of ejaculation frequency on spermatozoa survival in diluted Pleven Blackhead ram semen was investigated. Thirty-two ejaculates were examined. From each ram 4 ejaculates were collected at 10-min intervals in the morning and in the afternoon. Semen parameters, namely, color, density, transparency, volume, concentration, motility, and abnormal sperm, for each ejaculate were determined. The sperm motility was assessed from the moment of dilution up to 60 min at 10-min intervals, then again at 90 min and 120 min. The semen characteristics were determined by means of "Motic Image Plus" equipment and the data were processed statistically. Sperm volume and concentration in semen samples decreased gradually with increase in ejaculation frequency. The values were significantly lower for the 4th ejaculate compared to preceding ones (P < 0.05). The highest survival rate (P < 0.05) of sperm was found in the 2nd ejaculate, and this trend was preserved up to the second hour. Up to 50 min after dilution, the sperm motility did not change considerably, after which it was found to be reduced (P < 0.05). The frequency of ejaculation and the period of semen collection had an impact on sperm motility in extended and short-time stored semen from Pleven Blackhead rams. The spermatozoa in a 2nd ejaculate showed higher survival rates and could be recommended for additional processing.

The main priorities in the contemporary breeding of different animal species have been directed toward the use of intelligent approaches for accelerating genetic progress, ensuring animal welfare and environmental protection by reducing the release of manure and gas emissions

This study aimed to evaluate the effect of the ovarian status and steroid hormone concentration on the day of TAI on the reproductive performance of dairy cows subjected to estrus synchronization treatment and timed artificial insemination with sexed semen. Seventy-eight cyclic Holstein cows pre-treated with PGF2α-GnRH were divided in two groups—I (Preselect-OvSynch, n = 38) and II (OvSynch+PRID-7-day+eCG, n = 40)—and inseminated with sexed semen. The presence of preovulatory follicle (PF) with or without corpus luteum (CL), the PF diameter, the estradiol (E₂) and progesterone (P₄) concentrations on the day of TAI, the pregnancy rate (PR) and embryo loss were determined. On the day of TAI, 78.4% of all the pregnant cows presented a PF (mean size 1.80 ± 0.12 cm) without CL, low P₄ (0.59 ± 0.28 ng/mL) and high E₂ (12.35 ± 2.62 pg/mg) concentrations. The positive correlation between the size of the PF and the level of E₂ in the pregnant cows from group II was stronger than that of group I (R = 0.82 vs. R = 0.52, p < 0.05). The pregnancy rate on day 30 (57.5% vs. 36.8%) and day 60 (50% vs. 26.3%; p < 0.05) and the embryo losses (13% vs. 28.5%) showed better effects of treatment in group II. In conclusion, the ovarian status and the steroid hormone concentration on the day of TAI influence the pregnancy rates of dairy cows subjected to estrus synchronization and timed artificial insemination with sexed semen.

Aim of this study was to investigate the relationship between some kinematic parameters of ram semen and reproductive performance of dairy sheep after application of assisted reproductive technologies. The experiment was carried out with8 rams and 325 sheep from East Friesian breed and 7 rams and 162 sheep from Asaaf breed. Semen was collected by artificial vagina and subjected to primary assessment. Kinematic sperm parameters TM, PM, NPM, IS, VAP, VCL, VSL, LIN and STR were evaluated by computer-assisted semen analysis (CASA). All sheep were subjected to estrus synchronization by intravaginal sponges and artificially inseminated byfresh-diluted semen. Reproductive performance was recorded on the base of pregnancy rate (PR) and average litter size (ALS) calculated after lambing. Relationships between sperm kinematic parameters and these with the reproductive prformance were determined by correlation analysis. Significant differences between the mean values of age, body weight, ejaculate volume and sperm concentrationin the rams, and PR and ALS were not found. The sperm kinematic parametersshowed variability between individual rams. Total motility correlated positively with PM and LIN andnegativelywith NPM and IS (P<0.05). The correlation of PM with LIN and STR was positive, while this with NPM, IM and VCL was negative (P<0.05). A negative relationshipwas found of NPP and IS with STR and between LIN and VCL(P<0.05). The relationship of PM, VAP, LIN, STR with PR, and of LIN and STR with ALS (P<0.05) was positive, whereas this between VCL with PR was negative (P<0.05). In conclusion, the evaluation of the kinematic parameters by CASA is useful diagnostic and prognostic tool in sheep reproduction. The parameters PM, VAP, LIN and STR have a strong positive relationship (P<0.05) with the functional activity of ram spermatozoa and the reproductive performance of the sheep. They could be included as indicators in evaluation of the fresh semen quality in a selection of East Friesian and Asaaf rams with high fertility.