This study aimed to study the characteristics and subpopulations of spermatozoa from bulls with low and high reproductive performance based on pregnancy rates.Based on historical records of pregnancy rate from four farms, 24 bulls were selected. Two groups were established, with low pregnancy rates (n = 12; LOW), including bulls that presented pregnancy rates <52.27% (33.33% to 51.81%); and a group with high pregnancy rates (n = 12; HIGH), with pregnancy rates >52.27% (52.27% to 69.64%), after fixed-time artificial insemination (FTAI). The thawed sperm straws were analysed to sperm kinetics, morphology, plasma membrane integrity and sperm subpopulations. The LOW group exhibited a higher proportion of static cells (p < .05).In contrast, the HIGH group showed greater percentages for membrane integrity and total and progressive motility, and cells with fast and medium velocity (p < .05). In the cluster procedures, four sperm subpopulations were established. The low-fertility bulls presented the highest percentage of subpopulation 2 (41.46%), characterized by slow and progressive spermatozoa. The high-fertility bulls exhibited the highest percentage of subpopulation 3 (37.17%), characterized by fast and nonlinear spermatozoa. Results from this study indicated that bulls with greater percentages of fast and nonlinear spermatozoa seem to have greater fertilization capacity and the subpopulations analysis can be considered a tool to identify ejaculates with high fertility.

This experiment aimed to evaluate the effect of weight gain, body condition score and antral follicle count on the fertility of cows subjected to fixed-time artificial insemination. To this study, it was used 194 Nelore, pluriparous cows, between the 30th and the 45th day of the postpartum period. The cows were weighed, was classified by the body condition score and a transrectal ultrasound was performed in the ovaries to identify the corpus luteum and for counting the antral follicles. Then, the females were submitted to a hormonal protocol to perform the artificial insemination in fixed time. Thirty days after the artificial insemination, the cows were weighed again and the pregnancy was diagnosed by transrectal ultrasound. The pregnancy rate did not interact (P>0.05) with the body score condition, nor the presence of the corpus luteum, neither with the antral follicles count. The weight gain between the artificial insemination moment and the pregnancy diagnosis showed an interaction (P = 0.02) with the pregnancy rate. The weight gain average between the FTAI and the pregnancy diagnosis was 9.0 kg. The animals that gained up to 73 kg, showed higher pregnancy rate. In conclusion, the weight gain between the artificial insemination in fixed time and the pregnancy diagnosis influenced the pregnancy rate.

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This study aimed to standardize the CASA system for sperm concentration of cat epididymal samples, using a Neubauer chamber as the gold standard. Epididymal spermatozoa were collected from 44 adult cats. The sperm concentration was evaluated in the Neubauer chamber and by the CASA system at a dilution of 1:200. After assays, the ejaculates were separated into four groups according to the sperm cell count in the CASA system; A (≤ 100), B (101 to 400), C (401 to 800), and D (˃ 800). The statistical analysis measured the agreement between techniques using the Bland-Altman test. A 95% confidence interval was adopted and the statistical program MedCalc 18.2.1 was used. Groups A, B, and D presented disagreement between the CASA system and the Neubauer chamber. Only group C (401 to 800 cells per field) demonstrated agreement between methods. It can be concluded that evaluation of spermatic concentration of domestic felines by the CASA system is reliable when the reading is performed within the range of 401 to 800 cells per field, and could represent a viable alternative to the Neubauer chamber.

The present study aimed to evaluate the filtration for separating seminal plasma of boars’ ejaculate by means of sperm viability and the occurrence of hyperactivation and lipid peroxidation in fresh semen and after cooling for up to 96 hours. The ejaculate of eight healthy boars of different breeds was collected and the gelatinous portion was separated and discarded. In the laboratory, the semen was fractioned into three aliquots (groups G1, G2 and G3) as follows: G1: semen with plasma diluted in BTS (TOTAL BTS); G2: semen centrifuged at 600G/10’ (BTS CEN); and G3: semen filtered with the Sperm-filter® following dilution of the retained cells with BTS (BTS FIL). The analyses were performed at three moments: with fresh samples (D0) and after 48 (D2) and 96 hours (D4) of cooling at 17ºC. The kinetic evaluation was performed using the CASA system, which provided data for the classification of sperm hyperactivity. For lipid stress analysis, the TBARS (thiobarbituric acid reactive substance) test was performed. The variance analysis test was conducted to compare the results between the groups and moments analyzed. The results showed better total motility values (%) for G1 at D0 (67.9, P= 0.001), D2 (36.6, P= 0.004) and D4 (26.1, P= 0.003). The occurrence of hyperactivity was observed in G2 and G3 at moments D2 and D4. In addition, TBARS showed higher peroxidation levels for G1 at D0 (8.1 mM MDA/ml, P= 0.01), D2 (7.4 mM MDA/ml, P= 0.02), and D4 (6.41mMol MDA/ml, P= 0.008) when compared to G2 and G3. Since the filtration method did not demonstrate any damage to the sperm viability, the study concluded that sperm filtration is an accessible and valid tool to replace centrifugation.