Cooled semen for fixed-time artificial insemination in beef cattle

Abstract

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 (25×10 spermatozoa) were submitted to cooling for preservation at 5°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) 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 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, 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.

Investigation of in vitro measurable sperm attributes and their influence on electroejaculated bull semen with a fixed‐time artificial insemination protocol in AustralianBos indicuscattle

“…In consideration of differences in FTAI synchronization protocols and female reproductive status, the egg yolk‐based extenders have so far proven superior in achieving high pregnancy rates (Crespilho et al., ) in lieu of low‐density lipoprotein support of the sperm membrane in addition to glycerol (Vera‐Munoz et al., ) for electroejaculated B. indicus beef cattle. Our mean pregnancy rates in both treatment groups were comparable to earlier studies using FTAI in Nellore cattle with semen collected using electroejaculation and extended in a modified Tris‐egg yolk or commercial extender (Borges‐Silva et al., ; Crespilho et al., ; Papa et al., ). There was a significant reduction in pregnancy rate to FTAI using chilled‐stored semen compared to conventional cryopreserved semen, which therefore establishes probable extrinsic factors that adversely affect spermatozoa in liquid storage.…”

“…Ascertaining sperm longevity must be taken into account for FTAI, as insemination is performed at a fixed‐time point, based on average ovulation time, rather than in response to individual cyclic signs. In order to increase sperm longevity, a number of recent studies have started to incorporate chilled semen storage of semen in an effort to further improve pregnancy outcome of FTAI in B. indicus breeds (Borges‐Silva et al., ; Crespilho, Papa, de Paula Santos, & de Sa Filho, ; Crespilho et al., ; Papa et al., ). The advantages include a presumptive higher viability and longevity than cryopreserved semen, the opportunity to reduce the semen dose (low dose insemination and producing more doses per collected ejaculate), the availability of on‐farm bulls and decrease cost associated with acquisition, handling and storage of semen; namely attributed to the removal of the need to access liquid nitrogen, electricity and other specialized technical equipment (Schuh, ).…”

“…SATAKE ET Al. improve pregnancy outcome of FTAI in B. indicus breeds (Borges-Silva et al, 2015;Crespilho, Papa, de Paula Santos, & de Sa Filho, 2012a;Crespilho et al, 2014;Papa et al, 2015). The advantages include a presumptive higher viability and longevity than cryopreserved semen, the opportunity to reduce the semen dose (low dose insemination and producing more doses per collected ejaculate), the availability of on-farm bulls and decrease cost associated with acquisition, handling and storage of semen; namely attributed to the removal of the need to access liquid nitrogen, electricity and other specialized technical equipment (Schuh, 1992).…”

Effect of Sperm Concentration and Storage Temperature on Goat Spermatozoa during Liquid Storage

“…The advantages and disadvantages of AI with cooled semen samples in dairy cattle have been recently reviewed [ 2 ]; most of them are similar in the goat. The advantages include easier handling of cooled AI doses, transport and higher fertility rates compared to frozen AI doses [ 2 , 3 ]. Moreover, cooled doses require less spermatozoa per dose, which means more AI doses per ejaculate [ 4 ].…”

Evaluation of cooling and freezing systems of bovine semen

“…Another practical system for the transport of diluted semen that is also used in the field is Botutainer® (Botupharma, Botucatu, Brazil). According to the manufacturer, this system maintains the semen temperature at 5°C for up to 24 h. This transport box for cooled semen have been reported to be efficient in maintaining semen viable after cooling (Monteiro et al, 2013;Crespilho et al, 2014;Moscardini et al, 2014;Borges-Silva et al, 2016). Recently, programmable units for semen cryopreservation have been developed, which permit the selection of the desired cooling and freezing curve.…”