If you are going to start AI on May 1 then April is the month for preparation.
In simple terms Pregnancy rate is Submission rate x Conception rate.
In Irish terms submission rate is the amount of cows that are available for service (calved >42 days) that have been bulled in the first 3weeks of breeding. The target is 90% in a seasonal herd. The target for conception to 1st and 2nd service is about 65%. So if you have 100 cows and you have a submission rate of 90% then 90 cows should be bulled in first 3 weeks. If 65% of them hold then this leaves about 41 cows left to breed (that were eligible to breed in first 3 weeks.)
Second service will get another 27 cows (65%). This gives you in total 86cows in calf in 6 weeks.
So in short you can make up for a poorer conception rate with a good submission rate. While conception rate is affected by disease/health and energy (energy levels, dry matter intake; buffer feeding) submission rate is really just seeing them in heat.
Submission rate can be improved by:
- One month before breeding you need to check cows for heat or not – pre breeding. Tail paint/apply scratch cards to all cows 3 weeks before start of breeding and note any cows not bulling.
- Any cow calved 42 days and was not seen bulling within these 3 weeks should be scanned and treated if necessary. This avoids the loss of time further in breeding season and a cow that was once a February calver becoming an April calver.
- Any cow that was treated for retained cleaning should be re-examined before breeding. They may show heat even with a chronic womb infection.
- A vasectomised bull will aid in heat detection during the breeding season.
- Ensure all vaccinations are up to date and that maiden heifers have received their primary course ahead of breeding. Lepto/ BVD/ IBR can all interfere with conception rate.
- Implementing regular BCS (body condition score) on your farm leading up to breeding will highlight the high-risk cows that require attention. Ideally at breeding cows should have BCS of 2.75 -3.25. The high-risk group would include under conditioned cows, high yielders, lame cows and difficult calvers. Some of these would benefit from once a day milking or extra feeding.
- Consider keeping lame cows or under conditioned cows close to the parlour to optimise dry matter intake and reduce energy used to and from parlour.
- Ensure adequate mineral and trace element intake. Copper and Manganese deficiency can lead to silent heats. Selenium deficiency will affect conception rates.
Don’t forget the Bull
Bull should be given a once over before breeding starts. Fertility can be assessed by one of the vets. Mobility is vital and if showing signs of lameness, his feet should be tended too ahead of breeding to allow recovery time.