Sexed semen trials in Ireland have demonstrated a relative conception rate of 80%. If you are achieving 60% conception in cows conventionally, you will on average get 48% with sexed semen.
Sexed semen has a lower number of sperm than conventional semen, as it has undergone a sorting process, and bulls also vary in their conception rates following the sexing process. The variability in sexed semen conception rates is more than double that of conventional semen.
Munster Bovine offer the following advice to herdowners on how to maximize conception rates with sexed semen this breeding season.
Cow selection:
- Select cows that are retaining for 2022, want replacement heifers from and that have the highest chance of conception;
- Calve cows 60 to 90 days – the higher the six-week calving rate, the greater the choice;
- Younger cows have higher conception rates – be careful with some first calvers if body condition score (BCS) is low, and they have not coated off yet;
- A BCS 3.0 or greater is ideal;
- Select cows with no issues at calving or since calving (e.g. difficult calving, milk fever, RFM (Retention of fetal membranes), endometritis, lameness etc.);
- Keep intakes maximized during the breeding season. Watch the bulk tank – the percentage of protein and the volume – which are excellent indicators of energy.
Heifer selection:
- Ensure heifer is at target weight and BCS is greater than three;
- Choose heifers that cycle regularly and avoid its use on heifers on their first, or second cycle;
- Maximize intakes during breeding and the month following.
Heat detection and timing of AI:
- Sexed semen should ideally be used in the first 10 days of breeding and no later than the first three weeks. This is important due to the variability of the product;
- Synchronization has a major role to play in the success of sexed semen, as it allows precise timing of AI (artificial insemination). Animals can be bred in the first week of the breeding season and any repeats can be bred in the first month. Use the fixed timed AI synchronisation protocols for cows and heifers;
- Accurate heat detection is crucial. Only use sexed semen when you are sure of the heats. Use two methods in heifers – scratch cards and crayons. Use conventional semen when unsure of the heats;
- Ideal time for inseminating with sexed semen is 10 to 20 hours after the start of standing heat.
Sexed semen selection and handling:
- Use a panel of sexed semen sires to avoid the dependence on one or two sires, thereby spreading the risk
- Sires with superior proven field fertility in conventional semen are better candidates for sexed semen, however it cannot be predicted how bulls perform after the sexing process
- Thaw the sexed semen in a clean, descaled water flask with freshly-boiled, cooled water changed daily. Top-up as required to ensure the straw is fully submerged
- Thawing temperature is ideally 35° to 37° C for 45 seconds. Thaw a maximum of two straws at a time
- Inseminate animals within five minutes of thawing. Help the technician as much as you can to achieve this
Flexibility required to maintain fertility of the herd:
- Ideal time for inseminating with sexed semen is 10 to 20 hours after the start of standing heat, animals presented for AI that are at the beginning of heat should get conventional semen;
- If you get a poor response to synchronisation and your experienced AI technician informs you that they do not feel right, then use conventional semen;
- Spray-mark those heifers and cows that have lost their CIDR/PRID prior to removal at the synchronisation protocol for sexed semen, and use conventional semen on those animals;
- If very severe weather occurs, the bulk tank is dropping in volume or protein percentage, or if the animals are experiencing a setback – switch to conventional semen.
For more information on the Munster Bovine sexed semen line-up, contact your Munster Bovine farm relationship manager, or AI technician today.
Or to visit the Munster Bovine website;
