Influence of sperm number per straw on the post-thaw sperm viability and fertility of Swedish red and white A.I. bulls

• Published in: Acta veterinaria scandinavica Vol. 37; no. 4; pp. 461 - 470
• Main Authors: Januskauskas, A, Soederquist, L, Haaaard, M.G, Haaaard, M.C, Lundeheim, N, Rodriguez-Martinez, H
• Format: Journal Article
• Language: English
• Published: England BioMed Central 01.01.1996
• Subjects: Animals; BULLS; Cattle; CONSERVACION DEL SEMEN; CONSERVATION DU SPERME; ESPERMATOZOO; FERTILIDAD; FERTILITE; FERTILITY; Insemination, Artificial - veterinary; Male; MOUVEMENT; MOVEMENT; MOVIMIENTO; SEMEN; SEMEN PRESERVATION; Semen Preservation - veterinary; Sperm Count - veterinary; Sperm Motility; SPERMATOZOA; SPERMATOZOIDE; SPERME; SUECIA; SUEDE; SWEDEN; TAUREAU; TORO; VIABILIDAD; VIABILITE; VIABILITY
• DOI: 10.1186/BF03548086
• ISSN: 0044-605X; 1751-0147

Semen from 5 Swedish Red and White bulls, approved in the fertility and progeny testing programme of a bull center, was split-frozen to produce straws with 15 or 10 x 10(6) spermatozoa each (control and treatment dose, respectively). Post-thaw sperm viability was evaluated by visual assessment of sperm motility (MOT), measurement of ATP (Adeinosin Tri Phosphate) contents by luminometry, assessment of membrane integrity with combined fluorophore probes [Calcein AM (CAM)/Ethidium homodimer (EthD-1)] and by using a hyposmotic swelling test (ORT). The straws were used for a total of 16,651 artificial inseminations (A.I.). No statistically significant difference was recorded between the 2 treatments for any of the post-thaw sperm viability parameters. In addition, a significant bull effect was evident for most post-thaw sperm traits assayed. Significant variation in overall fertility (56-days NRR) was recorded among the bulls used. A.I. with a reduced number of spermatozoa (10 x 10(6)/straw) resulted in a 2%-units decrease (n.s.) compared with controls (67.8% +/- 4.8%, means +/- SD) in overall fertility. In the control split-sample (15 x 10(6) spermatozoa/straw), MOT did not show any statistically significant correlation with fertility (r = 0.41, p = 0.07). However, MOT was correlated with the percentage of spermatozoa depicting progressive motility (category A1, r = 0.45, p < 0.05) as assessed with CAM/EthD-1. The latter was correlated with ATP contents (r = 0.57, p < 0.01), expressed as the percentage of viable spermatozoa. Both CAM/EthD-1 and ATP contents showed a statistically significant correlation with ORT (r = 0.45, p < 0.05 and r = 0.61, p < 0.05, respectively). In the straws with the reduced sperm number (10 x 10(6) spermatozoa), post-thaw motility was significantly correlated with fertility (r = 0.50, p < 0.05) and ATP-total contents (r = 0.48, p < 0.05). CAM/EthD-1 and ATP contents (as million viable spermatozoa) were significantly correlated (r = 0.47, p < 0.05), CAM/EthD-1 was significantly correlated with ORT (r = 0.48, p < 0.05). In conclusion, the results indicated that the freezing-thawing of straws with a reduced sperm concentration (10 x 10(6) spermatozoa) did not alter the post-thaw viability or overall fertility of the bull semen used. However, in view of the significant bull effect found in the limited population studied, we recommend that such a reduction in sperm number/straw be based on the fertility of the bull in question.