The use of sexed semen, or semen sorted according to gender, is becoming more readily available to suckler farmers in Northern Ireland.
Sexed semen in comparison to conventional semen is more expensive, but it carries many advantages.
One major advantage is the ability to target maternal and terminal genetics to specific breeding stock.
The College of Agriculture, Food and Rural Enterprise’s (CAFRE’s) beef and sheep adviser, Colin McEvoy, recently met with suckler farmer John Cultra who is successfully using sexed semen on his suckler farm in Co. Down.
John operates a closed-herd policy and since he began using sexed semen on his suckler cows he does not need to breed as many of his herd to a maternal bull as the probability of a heifer calf from sexed semen is significantly increased.
This in turn allows for more of the herd to be bred to terminal sires while still maintaining the required number of replacement females being born.
The cows which are bred to terminal sires can be individually selected for artificial insemination (AI) or natural service to terminal sires with superior growth and carcass traits, resulting in better-performing calves which helps to increase the output from the herd.
Sexed semen challenges
While there are many benefits to sexed semen, it does come with challenges too. One issue John has noticed on his farm is the potential of lower conception rates compared to conventional semen.
To maximise conception rates, it is important to pay particular attention to straw handling and the AI procedure at the time of breeding.
On the Cultra’s farm, the use of sexed semen was prioritised on maiden heifers as they are generally more fertile and should have higher conception rates when compared to cows.
In John’s case, ten maiden heifers were synchronised and served via fixed-time AI (FTAI) with female sexed semen (semen to produce a female).
Six heifer calves were born to this first service, resulting in a conception rate of 60%.
By opting to use sexed female semen, John noted that birth weights were lower, aiding calving ease on these heifers which were calving for the first time at 24 months.
CAFRE has offered the following tips to suckler farmers considering the use of sexed semen:
- Decide if the semen is to be used on cows or heifers and identify is it suitable for maiden heifers;
- Ensure all intended vaccinations are administered, veterinary checks carried out and dosing is completed (if required);
- Forward-plan feeding requirements to ensure all animals to be served are on a good and rising plane of nutrition.
- If serving maiden heifers, ensure they have met their target service liveweight (60% of mature weight at service);
- Record details of those animals seen cycling already and monitor if they are cycling regularly;
- Consider whether these animals will be served on observed heats or synchronised. If synchronising, plan it out, discuss with your vet and AI technician if using one.
If farmers are breeding cows themselves, ensure all AI protocols are adhered to in terms of semen handling, thawing and insemination timing and technique:
- Pre-warm insemination guns to body temperature;
- Thaw straws at 35 – 37°C for 45 seconds;
- Complete insemination confidently and promptly within five minutes;
- Ensure adequate and proper handling facilities are available to reduce stress on the animals being served;
- Restrain animals to be served prior to thawing the straw;
- When heifers are to be inseminated with sexed semen after observed heats, AI should be conducted 14-20 hours after the onset of heat;
- Keep handling and stress on the animals to a minimum after service and maintain a good plane of nutrition post service;
- Plan to observe for repeats and consider using heat detection aids such as tail paint.
John plans to use sexed semen again this year, allowing him to continue producing female replacements from high-genetic-merit maternal bulls mated with the best maternal females in his herd.
With the variability in conception rates, he relies on an experienced, competent AI technician to carry out the AI procedure.
He is also careful in his animal selection; animal nutrition; pre and post service; and animal handling during and after service.
Although the use of sexed semen has added extra expense to his system, it gives John greater control and allows him the opportunity to choose the calf sex which can have a huge benefit within his breeding strategy.
