Angus Australia


Single or Multiple Sire Joining

Bulls that are being watched by other bulls are likely to serve females more often—they respond to an audience. Conception rates in multiple-joining groups are usually higher, which is understandable, since there are more services made in multiple joining groups than in single-joining groups.[23]

Multiple-sire joining involves a group of sires that are joined with a mob of cows at the same time rather than just a single bull (single-sire joining). Single sire joining is widely practised in the southern beef industry.

It reduces the risk of bull injury from fighting, but increases the potential for low calving percentage within individual mobs due to infertility or sudden loss of service availability.[18 ]

Particular care should be taken when single-sire joining.[8,18]

  • Assess all bulls annually, prior to joining
    – Only use those that meet the assessment guidelines
  • Join each bull to a maximum of 50 cows
  • Rotate bulls to make sure that any bull infertility is covered
  • Avoid wasting bull resources – joining sound bulls to less than 40 cows is wasteful and increases the cost of bull purchases
  • Observe all herds weekly during the joining period to ensure that the bull is working and has not been injured during mating

If a number of young bulls are to be used together, run them together for a few weeks before joining starts – they sort out their pecking order quickly and have few problems later.[8]


In multiple-joining situations, run bulls of the same age together.[12] Mixing ages of bulls in mating groups or mixing bulls shortly before or during mating may cause lower serving rates and conception as a result of establishing dominance within the herd.[20]

Set up your breeding system in conjunction with a suitably qualified vet. The size of paddocks, availability of water sources etc. all influence what system is best.