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Best Practice

What is a Joining Period?

The joining period is the time in which 95% of females mated should be pregnant1,2.

The standard recommended joining period is1,2:

Heifers: 6 weeks
Remainder of the beef herd: 9 weeks

Why are shorter joining periods important?

Reducing the duration of mating can:

reduce the time required to supervise calving heifers/cows
give cows more time to recover and maintain a 12-month cycle
identify superior calves at weaning to recognise which heifers to retain
tighten the herd's age structure to separate growth rate from age

Shorter Joining Periods


Ask your veterinarian/advisor if shorter joining periods are suitable for your herd

What factors affect the joining period?

Fertility and ideal joining periods in beef herds are driven by:

herd management

female nutrition

bull management
vaccination against preventable reproductive diseases

parasite control

genetic factors

Females should display heat twice during the 6-week mating period – Remove females from the herd if they do not conceive in the first 2 cycles2.


How does a shorter joining period make my herd more profitable2,4?

Less age spread
  • Produces a more even line of animals for sale
More recovery time post-calving before next mating
  • Important for heifers at second joining period because of longer post-calving anoestrus interval
Weaners will be older/heavier at any given date
  • Increases average selling price
  • Increases ability to reach ideal joining weight
Older/heavier heifers have higher conception rates
  • Fertility is strongly influenced by age/weight6

Preg-test early (6 weeks after joining) to determine pregnant females and get the most out of short joining periods6.

Shortening the joining period can increase value per head2,4

  • At start of joining, heifers from a 6-week joining period will be ~ 10 kg heavier/10 days older than heifers from a 12-week joining period

Difference in value of progeny in herds with different calving periods

% of herd calving in each cycle Pregnancy rate (All empty cows culled) Average weight lighter than 6 week joining (kg) Average value lost ($/head)* vs. 6-week mating
Cycle 1 2 3 4
6-week mating CR 70% 77% 23% 91%
9-week mating CR 65% 68% 24% 8% 96% 4
12-week mating CR 60% 61% 25% 10% 4% 98% 7 -$14
12-week mating CR 50% 54% 27% 13% 6% 93% 10 -$20
CR, conception rate; +Liveweight price $2.00/kg


Shorter joining periods can reduce your labour costs – For a 200-cow herd requiring 3 hours/day supervision at $30/hour, a 6-week calving period means a saving of $3,780 vs a 12-week calving period4.

How can I achieve a shorter joining period?

Take your time!

Optimal joining periods may take several years to achieve
If nutrition is good, aim to reduce joining periods by 1-2 weeks/year (particularly in heifers)3
Reducing joining periods too quickly may result in low pregnancy rates

Critical factors in achieving a short joining period:

Bull fertility
Management of first calf heifers
Heifer retention
Pregnancy testing

Ask your veterinarian or an experienced advisor for advice on whether shorter joining periods are suitable for your enterprise.

Achieving a shorter joining period – Nutrition

Nutrition is critical because it determines reproductive cycling activity
At calving, ensure females have condition score >2.5-3.0
Ensure adequate feed over the calving period so post-calving anoestrus interval is short

Joining Periods

Maximise profitability by timing calving with pasture growth curve to ensure good nutrition, early cycling and minimise supplementary feeding.

Nutrition is important

Heifers and cows with good nutrition will cycle early. This gives them a good chance of conceiving early to shorten calving patterns, increasing enterprise profitiability5

Achieving a shorter joining period – Bull Health

  • Only use high fertility bulls that have had a veterinary bull breeding soundness examination (VBBSE also referred to as BULLCHECK)10
  • Optimise herd fertility using genetic selection tools (e.g. parentage, i50K for Angus, Breedplan)
  • Scrotal size is strongly correlated with high semen output and female fertility10,11
    • Offspring reach puberty earlier, return to oestrus earlier and have shorter days to calving11



Check scrotal size of bull is above industry standards for British-bred bulls12

  • Bulls aged 18 months: >32 cm
  • Bulls aged 24 months: >34 cm

Achieving a shorter joining period – First Calf Heifers13

  • First calf heifers require special attention – return to oestrus is often longer than cows

Rates of return to oestrus following calving

Days after calving 40 50 60 70 80 90
Heifers returning to oestrus (%) 15 24 47 62 68 79
Cows returning to oestrus (%) 30 53 72 82 89 94

Tips for herds with nutritional challenges at joining

Join maiden heifers 3 weeks earlier (vs main herd) to allow more post-calving recovery time
Maintain tight calving pattern –late calving heifers are more likely to fail to conceive at next joining period


Prioritise nutritional feed to younger females (first and second calvers) to ensure they start cycling as soon as possible after calving.

Achieving a shorter joining period – Heifer Retention

Maintain a heifer retention rate >70% to ensure ample replacement females
Helps to minimise risks associated with a short joining period
Herds with shorter joining periods (<9 weeks) can join most heifers as they are older and heavier


Elimiate the risks associated with short joining periods by ensuring heifer retention rates are high (above 70%).
Early pregnancy testing is advisable. To tighten calving periods, consider foetal aging at the same time to eliminate late pregnancies from the herd.
Consult your veterinarian or an experienced advisor for more advice on achieving shorter joining periods.

Achieving a shorter joining period – Pregnancy Testing6

Early pregnancy testing (6 weeks after bull removal) is critical to achieving short joining periods
Pregnancy testing enables ageing of foetuses and tightening of joining period
Early pregnant females can be retained
Late pregnant females can be sold as "preg-tested in-calf"

Note: A Herd joined for 6 weeks with 85% pregnancy rate and culling of empty cows will be more productive than herd joined for 20 weeks with 98% pregnancy rate


Investigate unacceptably low pregnancy rates – rule out bull problems or infectious reproductive diseases (e.g. vibriosis, leptospirosis, pestivirus – vaccines available)

Shorter Joining Periods

Key Points

Reducing the joining period by 1-2 weeks/year in good conditions:

gives cows longer to recover and improves conception rates
allows identification of superior calves at weaning
produces heavier and more consistent animals for sale
reduces labour requirements

Points to consider

Ensure good nutrition, particularly for first and second calvers
Conception rate per cycle can be reduced  by reproductive diseases
Have a high heifer retention rate (>70%)
Ensure the use of fertile bulls
Use early preg-testing; consider selling late pregnant females

Finding and adjusting the optimal joining period may take several years but in the long term, your business and your herd will benefit from a shortened joining period

Zoetis has a range of vaccines to improve reproductive outcomes


(Ultravac® 7-in-1, Pestigard® and Vibrovax®) and parasiticides (Dectomax®) are critically important to achieve the overall goal of a healthy, productive and profitable herd

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:


Tech Note

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1. O’Brien G. Tightening the calving pattern. Victoria, Department of Primary Industries, 2013.

2. Meat and Livestock Australia. More Beef from Pastures. Module 6: Weaner throughput. 2013. Meat and Livestock Australia.

3. Meat and Livestock Australia. Making changes. Available from, accessed November 2014.

4. Data on File. John Webb-Ware 2013.

5. Meat and Livestock Australia. More Beef from Pastures. Procedure 1: Maximise the number of live calves per female. 2013. Meat and Livestock Australia.

6. NSW Department of Primary Industries. McConochie J. Selecting and managing beef heifers. New South Wales, Department of Primary Industries, 2007. Primefact #626.

7. Victoria Department of Primary Industries, 2014. Management of beef breeding cows. Available from Accessed November 2014.

8. Chapter 17: Chinchilla Vet. Chapter 17. Interpreting pregnancy diagnosis results for extensive beef production in northern Australia. Available from, accessed November 2014.

9. Pitchford W, et al. Simultaneous genetic improvement of maternal productivity, feed efficiency and end-product traits in variable environments. 2014. Meat and Livestock Australia.

10. Bertram J. Bull buying checklist. Future Beef, 2012. Available from, accessed September 2014.

11. University of New England. Understanding days to calving EBVs. Available from, accessed November 2014.

12. Victoria, Department of Environment and Primary Industries, 1995. Soundness of testicles in beef bulls, note number AG014. Available from, accessed November 2014.

13. Zoetis New Zealand Limited. Anoestrus in cattle. Available from, accessed November 2014.

14. Data on file. Rod Manning 2014.

15. Meat and Livestock Australia. Procedure 2, Control the mating period to maintain selected annual calving dates. Available from, accessed September 2014.

16. Feed.FIBRE.future. Are my beef cattle at the right condition score? 2007. Dairy Australia.

Further Reading

A Better Way To Buy