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Best Practice


Why it’s important

Bulls have a very significant influence on a healthy, productive and profitability herd. The average cow will produce 5–10 progeny in a lifetime in the commercial herd while the bull may produce 120–150 progeny in four to five years in its working life1.

Bulls must be sound for breeding:

  • willing and able to serve a high percentage of cows on heat
  • free of any abnormalities of the penis, testicles, feet and legs


Research conducted in Victoria demonstrated bulls were unsound for a range of reasons which increased with increasing bull age2,3.

A total of 25.2% of 2085 bulls over 3 years of age were unsound for breeding, of which3:

13.8% had locomotion problems

6.3% had penile problems
3.2% had a low libido, and

1.9% had testicular issues and / or poor sperm

Purchasing Bulls

There are a number of factors to consider:

  • BULLCHECK® - Veterinary bull breeding soundness examination (VBBSE) – a relatively quick and economic procedure for screening bulls prior to sale or use.4
  • Temperament a highly heritable trait.  Observe bulls in yards or paddocks prior to purchase and note any unusual/undesirable behaviour.
  • Estimated breeding values (EBVs) – provide objective measures of genetic potential for a trait. (For Angus breeders, consider bulls with EBVs enhanced with genomic information provided by i50K or HD 50K for Angus)
  • Vaccinations and health treatments only buy bulls that come with information about the vaccinations and health treatments they have received.

Bull Health

Preparing your bull for joining

Pre-Joining Examination:

A yearly examination of all bulls in a herd reduces the risk of poor performing bulls and bull breakdowns impacting reproductive outcomes5.

Ideally this should be done by an experienced cattle veterinarian

Physical examination – particularly  noting the feet and legs
Scrotum examination – palpate contents and measure scrotal circumference
Semen analysis – especially on bulls with obvious scrotal problems
Examination of internal genitalia - involves palpation of the seminal vesicles and the ampullae to ensure they are normal
Serving ability - assesses the bulls libido or will to serve.


Aim for a scrotal circumference of 35 cm and above (min. is 32-34cm depending on age and breed)6.



Ensure bulls are in BCS 3.0 for mating

  • Supplement to raise BCS or “let down” slowly if too fat
  • Bulls should be in good condition (BCS 3.0) at least 2 months prior to mating
  • Over-fatness can interfere with heat exchange of the testicles, compromising fertility7.


How many bulls?

  • A minimum of 2 bulls per 100 cows is recommended
  • Mating load, or bull power, will vary with bull breed, size, age, testicular size and management factors
  • Retain 1 bull in reserve for every 10 bulls in work so that injured bulls can be replaced as soon as they are identified
  • Working bulls of similar age together can reduce fighting
  • Plan mating groups eight weeks before joining and run bulls in those groups prior to mating to allow bulls to establish social groups.

Single or Multi-Sire Joining?

Conception rates in multiple-sire groups are usually higher

    • bulls that are being watched by other bulls are likely to serve females more often

    Single-sire joining reduces the risk of injury from fighting, but increases the risk of low calving percentage. Particular care should be taken when single-sire joining:

      • Assess bulls prior to mating - BULLCHECK
      • Join to 50 cows maximum
      • Rotate bulls to cover for any fertility issues
      • Observe closely to ensure bulls are working

      Bull Health

      Age of your Bulls

      Young bulls8

      Mate yearling bulls to a maximum of 25-30 females/bull
      Single-sire join or multi-sire join with bulls of the same age that are run together prior to mating
      Join yearling bulls for 6–8 weeks (2 cycles) only, then spell for at least 3 months
      After removing yearling bulls from their joining groups, place them on high quality feed to reduce the impact of nutritional stress of mating

      Older bulls9

      Because the rate of bull failure increases with age, it is essential that older bulls are checked prior to mating, ideally via BULLCHECK
      Bulls >5yo are especially prone to diseases and bull breakdown

      Disease Prevention

      Know the common cattle diseases in your locality and establish risk based control programs

      Diseases can be particularly costly when they affect the fertility of the bull and/or breeding females, resulting in lower than acceptable conception rates or an extended joining period


      All bulls should be vaccinated with:

      7-in-1 vaccine to protect against leptospirosis and clostridial diseases
      Vibriosis vaccine
      Pestivirus (BVDV) vaccine
      Three-day sickness vaccine (if in areas where this disease occurs)

      Bull Health

      Consult your veterinarians and draw up a policy for treating bulls on arrival and then annually.

      All bulls should be drenched, treated for lice, vaccinated with 7-in-1 (leptospirosis and key clostridial diseases) and for vibriosis and pestivirus annually.

      All bulls should be tested to ensure they are not persistently infected (PI) or carriers of pestivirus (BVDV).

      Key Products


      • Prevents the 5 common clostridial diseases (black leg, tetanus, pulpy kidney, black disease and malignant oedema) and leptospirosis
      • Prevents infertility and abortion and protects the unborn calf
      • Protects you, your family, your workers and your herd from leptospirosis


      • Protects against pestivirus – a major cause of infertility and abortion


      • Protect your herd by vaccinating all bulls annually

      Thank you

      Zoetis Australia would like to thank and acknowledge the contribution and review of content provided by the ReptoActive Steering committee.

      Dr John Wedd Ware

      Senior Consultant, Mackinnon Project, Faculity of Veterinary Science, University of Melbourne, VIC

      Dr Rod Manning

      Davilak Pastoral Co, cattle consultant for M.S & A, Mansfield, VIC

      Mr Mark Lucas

      Consulting Agronomist, Rural Business Consultant, Pasture Agronomy Service, Tumut, NSW

      Dr Bill Graham BVSc.

      Beef Cattle Consultant, Coolac Veterinary Services Coolac, NSW

      Mr Bill Hoffman

      Managing Director, Hoffman Beef Consulting Pty Ltd, Tregeagle, NSW

      Dr David Frith BVSc. MVSt.

      Director of Quirindl Veterinary Group, Quirindl, NSW


      For further information please refer to the following Tech Note:

      Repro-Active Logo

      Tech Note

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      1. Meat and Livestock Australia. Bulls. Available from,accessed September 2014.

      2. Locke I and Locke D. Wirruna News 2011. Available from, accessed August 2014.

      3. Data on file.

      4. Beggs DS. Veterinary bull breeding soundness evaluation (VBBSE), 2013. QLD, Australia. Australian Cattle Veterinarians.

      5. NSW Department of Primary Industries, 2006. Checking your bull is ready for joining. Primefact 249. Available from, accessed October 2014.

      6. Cummings B. Bull soundness – reproduction, NSW Department of Primary Industries, 1999. Available from, accessed December 2014.

      7. Victoria, Department of Environment and Primary Industries, 2006. Management of bulls at mating. Available from, accessed April 2013.

      8. NSW Department of Primary Industries, 2005. Yearling bulls – tapping their immense potential. Available from, accessed October 2014.

      9. NSW Department of Primary Industries, 2004. Bringing your new bull home. Available from, accessed September 2014.


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