Implementing controlled mating into your herd

Removing bulls now prevents calves being born next dry season (June–September) minimising time cows are lactating on poor quality feed. Ensure bulls have a secure paddock, not bordering with cows and have access to good quality feed.

During this time wean as many calves as possible. Determine what the lowest calf liveweight you can manage and focus on weaning calves off cows in lower condition (less than body condition score 3). Resources to help you manage weaning early

While you have cows in the yards, you can vaccinate cows for diseases that are relevant in your area e.g. botulism, clostridial diseases, leptospirosis and pestivirus (screen mobs first).

Keep in mind first-time vaccinations need a booster in 4–6 weeks.

More details about vaccinating your herd can be found here, don’t forget to get tailored advice from your local vet to ensure you are covered for your area.

Segregating your breeders by lactation status (wet or dry) will help with the different management requirements of each group. Accurate records are crucial during this time.

At this point you can also pregnancy test and foetal age. By foetal ageing, a predicted calving pattern can be determined which can be very useful for planning your future management program.

Segregating into calving groups may be useful to plan nutritional management and branding, weaning and bull removal in the following year.

To ensure the health and fertility of your bulls book an ACV (Australian Cattle Veterinarians) accredited vet to perform a Bull Breeding Soundness Evaluation on your bulls, ideally 2–3 months before mating (to give you time to buy new bulls or re-test if needed).

Vaccinate all bulls for vibriosis (they will require 2 doses a minimum of 4 weeks apart with the second being at least 2 weeks before joining with the cows), 3-day sickness, botulism and clostridial diseases.

Ensure your bulls have also been cleared for pestivirus (testing can be done through ear notch, hair or blood samples).

Supplement cows when back in the paddock if needed and dependent on season (weaning may be sufficient) to get them back up to body condition score 3 before mating.

Guide to body condition scores

Resources for managing breeder herd nutrition can be found here.

To help determine the level and type of supplementation required, diet quality of pastures can be determined through faecal testing – You can find more information HERE

What is a ‘Green date’ you may ask?

Typically, ‘green date’ is considered the date by when there is a specified chance of receiving over 50 mm of rain over 3 days (after 1^st September). This is where there is a better than average chance for sufficient rain to support pasture growth.

YOU CAN CALCULATE YOUR GREEN DATE HERE and reach out to your local extension officer if you need assistance.

The green date for your area helps determine when to best support wet cow nutrition. It is also important to consider how long you want your calving window to be. This will be a personal and business decision for you and will depend on:

• your country’s production capacity
• when calves will be sold – all at once or staggered
• the level of selection pressure you want to place on your females
• business input levels and labour efficiency
• your appetite for risk.

In order to best support wet cow nutrition, peak lactation demand begins 6 weeks after calving. To line up this demand with pasture quality we consider the green date and adjust as follows: Bulls go into mating 1 month after green date so the first calves are born 6 weeks before green date in the following year.

Use THIS breeding table to plan when to put your bulls out.

Put your bulls back in with your cows and heifers a month after your green date (so bulls would go out in mid-February for this example property).

Depending on your individual situation, you may adjust the timing based upon staff availability or weather and accessibility.

Conducting a forage budget at the end of the growing/wet season will help you to estimate how many animals can be carried through the dry season.

You can then forward plan management options if you end up short on feed e.g. agistment or sale.

Watch these videos to learn how to conduct a forage budget.

Wean as many calves as possible. Following the same principles as year one, cows in the lightest condition need to be weaned to support re-conception.

Muster your herd for second-round weaning,

Remove bulls and vaccinate and pregnancy test cows.

As a minimum remove cows not detectably pregnant. (Note if pregnancy testing is performed at the time of bull removal, pregnancies less than 6 weeks may not be detected).

You may want to segregate the breeders based upon foetal age also.

Testing your bulls at this time each year will create consistency in your management calendar and give you plenty of time before joining to purchase replacement sires.

Over time, you can expect:

• More calves in first-round weaning.
• Better cow condition – Less need for dry season supplements.
• Fewer second-round weaners.

Some advanced options to consider:

• Shorten joining period to tighten calving pattern (e.g., 3 months).
• Sell late-calving cows as surplus.
• Pregnancy test 6–8 weeks after bulls are removed.