Cooled semen for fixed-time artificial insemination in beef cattle

作者：Borges Silva Juliana C^*; Silva Marcio R; Marinho Daniel B; Nogueira Eriklis; Sampaio Deiler C; Oliveira Luiz Orcirio F; Abreu Urbano G P; Mourao Gerson B; Sartori Roberto

来源：Reproduction, Fertility and Development, 2016, 28(7): 1004-1008.

DOI：10.1071/RD14185

• cooling
• fertility
• sperm cryopreservation

This study evaluated the use of cooled semen in a fixed-time artificial insemination (FTAI) program compared with frozen-thawed semen to improve pregnancy rates in beef cattle. Ejaculates of three bulls were collected and divided into two treatments: (1) frozen-thawed semen and (2) cooled semen. Egg-yolk extender without glycerol was used for the cooled semen treatment. Straws (25x10(6) spermatozoa) were submitted to cooling for preservation at 5 degrees C for 24h, after which FTAI was performed. Nelore cows (n=838) submitted to FTAI were randomly inseminated using frozen-thawed semen or cooled semen. There was a 20% increase in the pregnancy per AI (P AI(-1)) using cooled semen compared with frozen-thawed semen (59.9 +/- 4.7 vs 49.4 +/- 5.0%; P<0.005). There was no difference in P AI(-1) among the bulls (P=0.40). The frozen-thawed semen had fewer functional spermatozoa than did the cooled semen when evaluated by sperm motility (61.7 vs 81.0%), slow thermoresistance test (41.7 vs 66.7%) and hypoosmotic swelling test (38.3 vs 53.7%; P<0.05). The percentage of sperm abnormalities did not differ between the freeze-thawing and cooling processes (18.6 vs 22.1%; P>0.05). Because there was less damage to spermatozoa and improvement in P AI(-1), the use of cooled semen instead of frozen-thawed semen is an interesting approach to increase reproductive efficiency in cattle submitted to a FTAI protocol.

• 出版日期2016