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Hot tips for top heifers

26 July 2023

Beef producers in the high rainfall zone of SA’s Limestone Coast region are making headway in improving breeder reproduction rates from heifers through to their second calving.

More than 30 producers – representing 19 beef businesses which collectively run 18,000 breeders across 50,000ha – are involved in a three-year, Producer Demonstration Site (PDS) with MacKillop Farm Management Group (MFMG) and the University of Adelaide. (This is a producer co-contributor PDS funded by MLA and MLA Donor Company.).

They’re developing and adopting best practice management systems to reduce reproductive losses and boost the health, nutrition, welfare and profitability of their herds.

The PDS involves expert-facilitated peer learning sessions at participants’ properties, assisted by a team of researchers, veterinarians and agronomists.

The PDS project facilitator, livestock consultant Elke Hocking, said the on-farm sessions were an important source of peer learning, and drove adoption of more investigative approaches to solve reproductive issues.

“Producers are comfortable discussing the ‘good, bad and ugly’ and learned a range of skills including body condition scoring, pasture assessment, genetics and bull selection to meet breeding objectives, pregnancy scanning and more,” Elke said.

Farm consultant Tim Prance demonstrates pasture testing and assessment to the group. Image: Meg Bell.

Here, Elke shares seven insights from the project.

1. Monitor to measure

Elke’s number one tip to improve heifer reproductive outcomes is to monitor and measure from the start – know the mature weight of your adult cows to set realistic target joining and calving weights for heifers.

“Continual monitoring of body condition score and liveweight throughout their reproductive cycle will help inform management decisions and demonstrate whether you’re achieving objectives,” Elke said.

In 2021, the PDS participants joined a monitor mob of 2020-drop heifers, which calved down in 2022. They collected liveweight and feed on offer measurements at weaning and joining, as well as pregnancy status, animal health and subsequent calving results through to their second calving in 2023. Results will be available for analysis by the end of 2023.

2. Weigh to go

As some producers were not regularly weighing cattle, and many didn’t know the reference weight of their adult cows, Elke said this information is important to set realistic targets for joining.

The recommended heifer joining target is 60% of mature cow weight. For example, this will be 330kg for a herd with 550kg mature cows, whereas in a herd with 700kg cows, the target is closer to 420kg.

“Reference weight is best obtained two weeks after mature cows’ calves are weaned, preferably at body condition score (BCS) 3,” Elke said.

“Each additional BCS is worth about 70–100kg (depending on breed) so you’ll need to adjust your reference weight back to what they’d be at BCS 3.”

3. Don’t overlook pasture

Meeting breeders’ nutritional needs requires good skills in pasture assessment and the ability to calculate supplementary feeding rates to meet shortfalls.

It’s important to test and measure pasture and feed availability.

“This ensures nutritional requirements are met during pregnancy so you’re able to reach growth rate targets,” Elke said.

“Poor joining and reproductive rates can be due to a lack of energy in pasture. Know your feed on offer.”

4. Get the balance right

Generally, the higher the body weight, the higher the reproduction rate. However, within different calving systems, some pasture and liveweight targets are more critical than others.

“For a late spring joining with a winter calving, liveweight at the start of joining is not as critical due to high growth rates from the increased flush of high quality spring feed available,” Elke said.

“However, liveweight becomes more critical for autumn calving systems with a May/June joining as there’s usually lower pasture availability and low growth rates of livestock during winter months.”

5. Focus on fertility

The PDS has been linked into a University of Adelaide project aimed at optimising heifer development and management (see ‘Putting research into practice’ below).

A key metric within this is ‘wet and pregnant early’ (WAPE), a measure which describes a heifer successfully getting in calf, raising a calf and getting back in calf within the first six weeks (two cycles) of joining. Once WAPE is achieved, heifers tend to be productive and robust as mature cows.

While pregnancy scanning for wet/dry can be done from six weeks after bull removal until one month prior to calving, fetal aging is a tool that can drive reproductive efficiency to achieve WAPE.

Fetal aging can be done 14–15 weeks from the start of joining and can identify heifers that got pregnant in the first cycle and those who took an additional cycle to conceive.

“Some group members are preferentially retaining these early fertile heifers and either selling the ‘lates’ or calving them down as a separate mob for easier management during calving,” Elke said.

For examples of energy requirements for different livestock classes see Table 1 in the More Beef from Pastures online manual.

6. Bulls matter

Fixed-time AI condenses calving and allows heifers more recovery time before second joining. It’s a cost-effective way to attain top genetics, however it’s labour intensive and still requires back-up bulls to be used.

Producers should check bulls for fertility and reproductive diseases prior to joining.

“There’s nothing worse than a dud bull shooting blanks. Once cows are through their second pregnancy, they’re pretty bullet proof – any issues are likely due to either the bull or disease,” Elke said.

Clear breeding objectives and selecting bulls based on Estimated Breeding Values (EBVs) for desired traits will deliver results. The EBV most closely associated with getting heifers in calf early is Days to Calving.

Read how another PDS used fixed-time AI to improve heifer productivity.

7. Combat dystocia

Rethinking how to combat dystocia, a common cause of reproductive loss, led the PDS group to some new genetic insights.

“No-one wants to pull calves – it’s hard work and a significant factor in cow and calf mortality,” Elke said.

“For many producers, selecting for shorter gestation and calving ease EBVs has been key to reducing dystocia in heifers, along with low to moderate birth weights.

“Limiting feed in heifers prior to calving to reduce birth weights to help prevent dystocia can backfire with heifers lacking energy to push calves out.

“Heifers need adequate nutrition throughout late pregnancy to sustain their growth rates and milk production, in addition to growth of the fetus,” Elke said.

It’s equally important that heifers grow well prior to joining and in the first half of pregnancy.

This means they don’t have to catch up during the second half of their pregnancy when there’s the risk of nutrition increasing calf size.

Table 1: Calving system management calendar. This table represents timelines for three of the most common systems amongst the project participants

Putting research into practice

Davies Livestock Research Centre director Professor Wayne Pitchford and PDS project facilitator and consultant Elke Hocking. Image: Meg Bell.

Streamlining the delivery of research outcomes to producers was one of the key factors behind the decision to link this PDS to the University of Adelaide’s ‘Optimising heifer development and management to increase whole herd productivity’ project.

The project is led by Dr Michelle Hebart and falls under the university’s Davies Livestock Research Centre.

“It’s two-way, we’re getting access to research results hot-off-the-press and simultaneously, producers are informing researchers how they want findings delivered. Having researchers on the ground is truly collaborative – it’s one of the most exciting parts of the project,” PDS facilitator Elke Hocking said.

Producers are testing a calculator being developed by University of Adelaide’s Darren Koopman to determine the economic impact of various reproductive rates and management decisions.

Once finalised, it will help answer whether increasing heifer conception rates to 88–90% will translate into increased profitability. The calculator is due to be released in late 2023.

Veterinarian Sean McGrath provided advice on reproductive health issues during the project. Image: Meg Bell.

Veterinarian Dr Sean McGrath has been instrumental in investigating how animal health, husbandry and welfare issues impact reproductive performance. At each session he’s answered producers’ animal health questions around monitoring and testing for worms, trace elements and reproductive diseases, bull testing, managing dystocia and ‘when to call the vet’.

Sean oversaw calf post-mortems to identify causes of death and advocates for an investigative approach in preventing problems. Producers have increasingly sought more accurate diagnostic procedures – with access to project funding for blood testing and Sean’s expertise invaluable.

Sean identified intestinal worms and trace element deficiencies (copper, cobalt and selenium – common in many southern Australian regions) as the main health issues impacting reproduction efficiency – the main effect being heifers not reaching target weights. He advises proactive testing and supplementation for any deficiencies and watching egg counts in young stock post weaning after the autumn break. Well-timed use of treatments will keep stock on track.

“Preventative plans and using strategic control points such as summer drenching or appropriately timed trace element supplementation, can ensure heifers are getting to target weights for joining and calving,” Sean said.

Four ways to target heifer productivity

  1. To achieve 85% conception rate in six-week heifer joinings, aim for pre-joining liveweights of 60% of mature cow weight.
  2. To optimise re-conception, the target liveweight for heifers leading into their first calving is 85–90% of the mature cow reference weight. BCS of 3 and high quality feed on offer will also contribute to re-conception success.
  3. Heifers are still growing so they have specific nutritional requirements – measure feed availability accordingly. Keep them on track to reach growth-rate targets before joining.
  4. Test and measure rather than guess – blood tests will identify any mineral deficiencies or animal health issues.

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