Whether you are thinking of combining artificial breeding (AB) and natural mating bulls, extending the AB period to reduce the number of bulls needed, re-starting AB in the last few weeks of mating, or thinking of implementing AB through the whole mating period, consider the risks and benefits of each option.
The best option is dependent on each individual farm’s situation and there are pros and cons to all of them. We’ve outlined some of the key considerations to using bulls or extending your AB period.
- Allows a shortened AB period
- Reduce heat detection requirements – staff, heat detection aids etc.
- Allows mating to occur where AB is impractical (ie. R2’s at run-off)
- Can be kept and used for multiple seasons
- Retain some value as they can be sold or sent to the works for a return
- Biosecurity risk – can be well managed through testing and/or vaccination with some diseases (ie. BVD) but Mycoplasma bovis presents a more difficult situation
- Associated bull issues – aggression, lameness, H&S etc
- Availability of leasing bulls
Advice this season
- Source well grown yearling virgin bulls directly from closed herds wherever possible (ie. most stud farms)
- Consider visiting the farm you are buying from and select the animals if behaviour of the bull is a concern
- Ask questions about animal health, animal movements, and biosecurity practices on the source farm
- If you find a bull supplier that your due diligence considers safe, pre-book next year’s bulls with them too.
- Investigate the NAIT history of any bull purchases/leases
- The risk of service bulls carrying Mycoplasma bovis is low, particularly on farms that have had no signs of disease and that have minimal stock incoming from other farms. Discuss whether getting bulls tested prior to purchase/use should be considered with your vet.
- Quarantine bulls after arrival for at least 7 days, and ideally 2-4 weeks prior to putting with cows or heifers
- Rearing your own service bulls for future seasons is an option but take into account the various inputs of money, effort, grazing and hassle managing bulls on your milking platform or run-off
Extending AB period
- Reduces risk of introducing disease as less or no bulls are required
- Increased number of dairy replacements
- Opportunity to create extra income from surplus dairy replacements and higher value calves (eg. beef)
- Potentially increased genetic gain (more selection pressure on replacements is possible)
- Better monitoring of entire mating performance (all matings are recorded)
- Risk of poorer reproductive performance especially in herds where performance is not optimal – Talk to your advisor, discuss the checklist below to help you identify what your current situation is and consider if making changes suits you in the upcoming season or if a staged approach should be taken.
- Extended heat detection period
- Silent/quiet heats have a higher potential to be missed - good results are reliant on excellent heat detection maintained throughout the entire AB period
- Fewer animals cycling as more become pregnant making heat detection more challenging
- Potential for incorrectly inseminating more pregnant cows if reliant on human heat detection (cost, loss of early pregnancies)
- Increased logistical considerations – staffing, heat detection aids, semen and tech
Advice this season
Extending the AB period or going all AB will not be suited to everyone.
Before you make the decision, here are some key points to consider.
- Communicate. If you decide to extend your AB programme, communicate this to all of those involved in making your plan happen - your vet, your semen supplier, your AB tech, your rural professionals and your team on farm.
- If you increase the use of synchrony of heifers and cows, plan ahead to cater for the increase on the numbers of cows calving within a very short timeframe, from a feed demand point of view, in the following calving season.
- If you plan to change the approach with your heifers and use AB, discuss how to maximise their performance with your vet. Liveweight, general health and BVD control as well as the practicalities and logistics of synchrony programs, grazier facilities and technician services should be taken into account.
- Further information on areas affecting a herd’s reproductive performance and management options can be found in the InCalf book.
If you don’t meet all of these criteria, it does not mean that you can’t extend your AB period or adopt all AB. However, you will need to have a good solid plan in place for how you are going to mitigate those criteria you don’t meet, so you set yourself and your herd up for a successful mating period.
- Repro performance is at national average or higher
- A 6-week in-calf rate above 65%
- A 3-week submission rate of 80% or higher
- A conception rate of 50% or higher
- Less than 20% short returns
- Fewer than 15% cows treated for anoestrous
- Your herd is healthy and primed to have a successful mating
- BVD free (BVD can have strong reproductive performance consequences)
- No increase in cow health problems through calving (e.g. milk fever and mastitis)
- First calvers have reached their target liveweight for calving
- No increase in late calvers
- You have the skills and staff to carry out prolonged heat detection as extended AB or all AB makes accurate heat detection even more critical as these can increase heat detection to 10-12 weeks.
- Seek advice – Talk to your farm advisor, vet and a farmer that has already extended AB or gone all AB and work out if the cost-benefit fits your plan.
Information supplied by the National Reproductive Strategy Group, members represented from DairyNZ, Federated Farmers of New Zealand, LIC, CRV, Society of Dairy Cattle Veterinarians, New Zealand Veterinary Association, Fonterra, Synlait and Open Country Dairy.