Handle Semen for Optimal Fertility
Dairy management team members monitor production data, health events and reproductive outcomes regularly. Little emphasis, however, is usually spent evaluating semen handling. Unfortunately, this is a critical oversight, as every successful AI program begins with proper semen handling.
AI studs provide a highly fertile product. The maintenance of male fertility is the responsibility of the producer, farm employees and AI technicians once the semen is purchased and transferred to the owner’s liquid nitrogen tank.
A detailed semen inventory should be easily accessible so straws can be located and removed from the tank quickly to avoid exposure to ambient temperature. When removing a straw from a liquid nitrogen tank, it is imperative the technician keeps the canister, cane and unused semen straws as low as possible in the neck of the tank. A best management practice is to keep all unused straws below the frost-line in the neck of the tank.
With the adoption of timed AI protocols, numerous cows must be inseminated on a given day. AI technicians routinely thaw multiple straws of semen simultaneously. Research results provide evidence simultaneous thawing and sequence of insemination had no effect on fertility. In the same study, elapsed time from initial thaw to completion of fourth AI, which occurred within 11 minutes, also had no effect on fertility.
Sexed Semen Has Improved
Sexed semen is a different product than conventional semen. Recent improvements in sexed semen processing are promising; however, the reasons for lower fertility following AI with sexed semen, as compared to conventional semen, are unknown. It is clearly important to handle sexed semen with care to maximize fertility.
Sexed semen is packaged in 0.25-mL straws. While those straws can be handled similarly to 0.5-mL straws, the smaller diameter makes them more sensitive to handling errors. Research demonstrates a decline in sperm motility over time when sexed semen is not handled properly. Providing thermal protection for sexed semen at normal body temperature resulted in the greatest maintenance (least decline) of progressive motility, as compared with sexed semen held at 108°F (heat shock) or 40°F (cold shock), both of which resulted in sharp declines in progressive motility over time.
To maximize the potential fertility in each straw of semen, caution must be exercised during semen handling. A recommendation as to the number of straws that may be thawed simultaneously detracts from the overall importance of proper semen handling for successful AI.
Fertility will most likely be maximized when technicians:
- Follow recommendations for thawing semen.
- Maintain thermal protection of straws during AI gun assembly and transport.
- Adhere to appropriate hygienic procedures.
- Deposit semen in the uterus of the cow or heifer as soon as possible. Ideally this is within 5 to 10 minutes after thawing for sexed semen, and within 10 to 15 minutes for conventional semen.
The range in fertility achieved by technicians following the use of sexed and conventional semen is quite pronounced and could be due to many factors, including semen handling errors. Handle semen with care and consider evaluating semen handling procedures regularly.
Joseph C. Dalton, Ph.D. is a professor at the University of Idaho. His research is focused on increasing the efficiency of AI in dairy cattle, including heat detection accuracy, synchronization programs and AI technician proficiency.
Note: This story appeared in the November issue of Dairy Herd Management.
Thu, 11/09/2017 – 08:00
Source: Dairy Herd