There are M.bovis risks associated with bringing bulls onto your property and joining them with your herd/heifers versus moving to a full AI system.
Sitting down with your farm’s veterinarian for a one-on-one Repro Ready consult ahead of mating will provide the most specific and pertinent advice to you and your situation. That being said,
this article will hopefully provide some food for thought and perhaps initiate these more formal discussions.
Bulls & Biosecurity
Bulls are a notable biosecurity risk given that they are usually purchased off-farm, transported in at mating time (time of higher stress) and have intimate contact with a large number of cows in your herd on any given day. If they arrive carrying a pathogen (BVD, Mycoplasma, Theileria for example) they have the ability to rapidly spread these diseases. Mycoplasma testing of bulls is possible through a tonsillar/nasal swab and when large numbers of bulls in a line are tested negative, this can provide an indication of reduced risk. Unfortunately, there are no guarantees with this disease however and no amount of testing for Mycoplasma can give you 100% certainty.
Pro’s
- Bulls allow a shortened AI period – reduced heat detection requirement (staff, heat detection aids etc)
- Bulls offer consistently accurate heat detection (ie. picking up quieter/silent heats)
- Allow mating to occur where AI is impractical (ie. R2’s at run-off)
- Beef calves to sell.
Con’s
- Biosecurity risk – can be well managed through testing and/or vaccination with some diseases (ie. BVD) but with Mycoplasma bovis there will always be a risk as testing cannot guarantee an animal is free of the bacteria.
- Cost
- Associated bull issues – aggression, lameness, H&S etc.
Advice this season
- Source bulls from closed herd situations wherever possible (i.e. most stud farms)
- Mycoplasma testing of bulls prior to purchase should be considered – NB. It will not guarantee that they are free of the disease but provides an additional level of confidence
- Investigate the NAIT history of any bull purchases/leases
- Quarantine bulls after arrival for 2-4 weeks prior to putting with cows
- Consider rearing your own service bulls for future seasons
- Or if you find a bull supplier that your due diligence considers safe, it would be advised that you pre-book next year’s bulls with them too.
Fully Artificial Insemination Mating
All AI as a mating strategy can instantly improve your biosecurity profile, with no new stock (bulls) introduced to your herd during mating. There are some important considerations prior to making this decision, however, which, if overlooked could have a dramatic impact on your overall mating performance. Moving from 4 or 5 weeks of AI to a full 10 weeks of AI mating is not a decision to be made on a whim and should be discussed thoroughly with your veterinarian.
Pro’s
- No bulls required – reduced biosecurity risk along with the other Bull con’s listed above
- Increased number of dairy replacements (higher value?)
- Potentially increased genetic gain (more selection of replacements)
- Better monitoring of entire mating performance (all matings are recorded)
- AI and heifer synchrony can be used to reduce the total numbers of bulls and capture advantages of faster genetic gain.
Con’s
- Good results are heavily reliant on excellent heat detection maintained throughout the entire mating period
- Increased costs – staffing, heat detection aids, semen and tech insertion fees
- Silent/quiet heats have a higher potential to be missed
- Requires AI techs to be available through until December
Advice this season
- Work with your veterinarian to assess the situation on your farm – using Infovet we can review historic results and heat detection ability and use this to estimate the impact of a move to full AI on your overall performance
- Don’t jump into all AI without first consulting professional advice and fully considering all implications
- Success will be achieved through good planning and preparation which needs to start now.
Dr Greg Lindsay BVSc Veterinarian & Director
